echnologies and Costs for Control of Microbial echnologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts Contaminants and Disinfection Byproducts T PREPARED FOR:

U. S. ENVIRONMENTAL PROTECTION AGENCY Office of Ground Water and Drinking Water PREPARED BY:

THE CADMUS GROUP, INC. 1901 North Fort Myer Drive Suite 900 Arlington, VA 22209 MALCOLM PIRNIE, INC. 1900 Polaris Parkway Suite 200 Columbus, OH 43240 US EPA CONTRACT: 68 C 02 026 Work Assignment: 1 21 June 2003 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 i Table of Contents Chapter 1: Introduction 1.1 Purpose of Technology and Cost Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1.2 Existing Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 1.2.1 Surface Water Treatment Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 1.2.2 Information Collection Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 1.2.3 Interim Enhanced Surface Water Treatment Rule . . . . . . . . . . . . . . . . . . . . . . 1 3 1.2.4 Stage 1 Disinfectants and Disinfection Byproducts Rule . . . . . . . . . . . . . . . . . . 1 4 1.2.5 Long Term 1 Enhanced Surface Water Treatment Rule . . . . . . . . . . . . . . . . . . 1 4 1.2.6 Filter Backwash Recycling Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 1.3 Public Health Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 1.3.1 Pathogenic Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 1.3.2 Disinfectants/ Disinfection Byproducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 1.4 Proposed Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 1.4.1 Long Term 2 Enhanced Surface Water Treatment Rule . . . . . . . . . . . . . . . . . . 1 6 1.4.2 Stage 2 Disinfectants/ Disinfection Byproducts Rule . . . . . . . . . . . . . . . . . . . . . 1 7 1.5 Technologies Evaluated for the Control of Pathogens and Disinfection Byproducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 1.6 Document Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9 Chapter 2: Technologies for DBP and Microbial Contaminant Control 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 2.2 Alternative Disinfection Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 2.2.1 Chloramination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 <IP_ADDRESS> DBP Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 2.2.2 Chlorine Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 <IP_ADDRESS> DBP Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 7 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 8 2.2.3 Ultraviolet Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 8 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 10 <IP_ADDRESS> DBP Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 12 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 12 2.2.4 Ozone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 14 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 16 <IP_ADDRESS> DBP Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 18 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 20 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 ii 2.2.5 Microfiltration and Ultrafiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 21 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 22 <IP_ADDRESS> DBP Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 26 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 26 2.2.6 Bag and Cartridge Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 27 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 28 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 30 2.2.7 Bank Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 31 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 31 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 32 2.2.8 Second Stage Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 32 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 33 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 34 Filter Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 34 Filter Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 34 Filter Hydraulics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 35 2.2.9 Pre Sedimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 35 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 35 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 36 Short Circuiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 36 Coagulant Dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 36 2.2.10 Watershed Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 36 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 36 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 38 2.2.11 Combined Filter Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 38 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 38 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 39 Coagulant Dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 39 Filter Ripening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 39 Filter Breakthrough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 40 Filtration Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 40 Backwashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 40 2.3 DBP Precursor Removal Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 40 2.3.1 Granular Activated Carbon Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 40 <IP_ADDRESS> DBP Precursor Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 42 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 42 2.3.2 Nanofiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 44 <IP_ADDRESS> Efficacy Against Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 45 <IP_ADDRESS> DBP Precursor Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 47 <IP_ADDRESS> Factors Affecting Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 49 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 iii Chapter 3: Technology Design and Criteria 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 3.2 Base Treatment Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 3.3 Alternative Disinfection Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 3.3.1 Chloramination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 3.3.2 Chlorine Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 3.3.3 Ultraviolet Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 3.3.4 Ozone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7 3.3.5 Microfiltration and Ultrafiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 8 3.3.6 Bag and Cartridge Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 10 3.3.7 Bank Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 11 3.3.8 Second Stage Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 11 3.3.9 Pre Sedimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 12 3.3.10 Watershed Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 12 3.3.11 Combined Filter Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 14 Installing Backwash Water Polymer/ Coagulant Feed Capability . . . . . . . . . . . . . . 3 15 Installing Additional Coagulant Feed Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 15 Adding Filter Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 15 Adding Filter to Waste Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 16 Installing or Replacing Filter Rate of Flow Controllers . . . . . . . . . . . . . . . . . . . . 3 16 Increasing Plant Staffing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 16 Increasing Staff Qualifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 16 Purchasing or Replacing Bench Top Turbidimeters . . . . . . . . . . . . . . . . . . . . . . . 3 16 Purchasing or Replacing Jar Testing Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . 3 16 Purchasing or Replacing a Particle Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 16 Staff Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 17 3.4 DBP Precursor Removal Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 17 3.4.1 Granular Activated Carbon Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 17 3.4.2 Nanofiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 19 Chapter 4: Technology Costs 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 4.2 Approach for Cost Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 4.2.1 Cost Components and Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . 4 3 O& M Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 4.2.2 Cost Indices and Unit Cost Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5 4.2.3 Cost Build up Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7 4.2.4 Lump Sum Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7 4.2.5 Cost Modeling Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7 <IP_ADDRESS> VSS Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 8 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 iv <IP_ADDRESS> Water Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 8 <IP_ADDRESS> W/ W Cost Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 9 4.2.6 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 9 Permitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 9 Piloting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 10 Land . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 10 Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 11 Operator Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 12 Public Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 12 4.3 Estimation of Annualized Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 12 4.4 Alternative Disinfection Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 13 4.4.1 Chloramination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 13 <IP_ADDRESS> Summary of Chloramine Capital Cost Assumptions . . . . . . . . . . . . . . . 4 14 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 14 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 15 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 15 <IP_ADDRESS> Summary of Chloramine O& M Cost Assumptions . . . . . . . . . . . . . . . . 4 15 4.4.2 Chlorine Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 21 <IP_ADDRESS> Summary of Chlorine Dioxide Capital Cost Assumptions . . . . . . . . . . . 4 21 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 21 Feed Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 21 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 22 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 22 <IP_ADDRESS> Summary of Chlorine Dioxide O& M Cost Assumptions . . . . . . . . . . . . 4 23 Feed Equipment ( systems smaller than 2.0 mgd) . . . . . . . . . . . . . . . . . . . . . . 4 23 Chemical Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 23 Materials, Electricity, and Labor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 23 4.4.3 Ultraviolet Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 27 <IP_ADDRESS> Summary of UV Disinfection Capital Cost Assumptions . . . . . . . . . . . . 4 27 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 27 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 28 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 28 <IP_ADDRESS> Summary of UV Disinfection O& M Cost Assumptions . . . . . . . . . . . . 4 28 4.4.4 Ozone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 38 <IP_ADDRESS> Summary of Ozonation Capital Cost Assumptions . . . . . . . . . . . . . . . . 4 38 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 38 pH Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 43 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 43 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 43 <IP_ADDRESS> Summary of Ozonation O& M Cost Assumptions . . . . . . . . . . . . . . . . . 4 44 4.4.5 Microfiltration and Ultrafiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 52 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 v <IP_ADDRESS> Summary of MF/ UF Capital Cost Assumptions . . . . . . . . . . . . . . . . . . 4 52 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 52 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 <IP_ADDRESS> Summary of MF/ UF O& M Cost Assumptions . . . . . . . . . . . . . . . . . . . 4 58 Membrane Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 58 Performance Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 Clean in Place Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 Labor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 POTW Surcharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 4.4.6 Bag and Cartridge Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 <IP_ADDRESS> Summary of Bag and Cartridge Filter Capital Cost Assumptions . . . . . . 4 64 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 <IP_ADDRESS> Summary of Bag and Cartridge Filter O& M Cost Assumptions . . . . . . 4 66 Bag and Cartridge Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 Labor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 4.4.7 Bank Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 4.4.8 Second Stage Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 4.4.9 Pre Sedimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 71 4.4.10 Watershed Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 71 4.4.11 Combined Filter Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 72 <IP_ADDRESS> Installing Backwash Polymer Feed . . . . . . . . . . . . . . . . . . . . . . . . . . 4 75 <IP_ADDRESS> Installing Additional Coagulant Feed Points . . . . . . . . . . . . . . . . . . . . 4 75 <IP_ADDRESS> Filter Media Addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 75 <IP_ADDRESS> Filter to Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 76 <IP_ADDRESS> Filter Rate of Flow Controller Replacement . . . . . . . . . . . . . . . . . . . 4 77 <IP_ADDRESS> Increase Plant Staffing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 78 <IP_ADDRESS> Update Plant Staff Qualifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 78 <IP_ADDRESS> Purchase Turbidimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 78 <IP_ADDRESS> Purchase Jar Test Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 79 <IP_ADDRESS> Purchase Particle Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 79 <IP_ADDRESS> Staff Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 79 <IP_ADDRESS> Average Plant Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 81 4.5 DBP Precursor and Microbial Removal Technologies . . . . . . . . . . . . . . . . . . . . . . . . 4 83 4.5.1 Granular Activated Carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 83 <IP_ADDRESS> Summary of GAC Capital Cost Assumptions . . . . . . . . . . . . . . . . . . . . 4 84 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 vi Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 84 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 86 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 86 <IP_ADDRESS> Summary of GAC O& M Cost Assumptions . . . . . . . . . . . . . . . . . . . . 4 88 GAC Usage Rate and Replacement Costs . . . . . . . . . . . . . . . . . . . . . . . . . . 4 88 Labor Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 89 Natural Gas Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 91 Performance Monitoring Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 91 Maintenance Materials Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 92 VSS Model Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 93 4.5.2 Nanofiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 100 <IP_ADDRESS> Summary of NF Capital Cost Assumptions . . . . . . . . . . . . . . . . . . . . 4 100 Process Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 100 Capital Cost Multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 102 Indirect Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 102 <IP_ADDRESS> Summary of NF O& M Cost Assumptions . . . . . . . . . . . . . . . . . . . . . 4 104 Clean in Place Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 104 Acid/ Anti Scalant and Caustic Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . 4 104 NF Membrane Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 105 Cartridge Filter Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 105 Repair, Maintenance and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 105 Performance Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 106 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 106 Labor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 106 POTW Surcharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 107 4.6 Annualized Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 110 Chapter 5: References Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 vii List of Exhibits Exhibit 2.1: Comparison of CT Values for Free Chlorine and Chloramine . . . . . . . . . . . . . . . . . . 2 3 Exhibit 2.2: Comparison of CT Values for Free Chlorine and Chlorine Dioxide . . . . . . . . . . . . . . . 2 6 Exhibit 2.3: Summary of Chlorine Dioxide CT Values for Cryptosporidium Inactivation . . . . . . . . 2 7 Exhibit 2.4: Comparison of UV Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 9 Exhibit 2.5: UV Dose Requirements for Inactivation of Cryptosporidium, Giardia, and Viruses During Validation Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 11 Exhibit 2.6: Comparison of Air and Liquid Oxygen Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 15 Exhibit 2.7: Comparison of CT Values for Free Chlorine and Ozone . . . . . . . . . . . . . . . . . . . . . 2 16 Exhibit 2.8: Reported Ozonation Requirements for 2 log Inactivation of Cryptosporidium Oocysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 18 Exhibit 2.9: CT Considerations for Cryptosporidium Inactivation . . . . . . . . . . . . . . . . . . . . . . . 2 21 Exhibit 2.10: Pressure Driven Membrane Separation Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . 2 22 Exhibit 2.11: MF and UF Studies Documenting Bacteria Removal . . . . . . . . . . . . . . . . . . . . . . . . 2 23 Exhibit 2.12: MF and UF Studies Documenting Giardia Removal . . . . . . . . . . . . . . . . . . . . . . . . 2 24 Exhibit 2.13: MF and UF Studies Documenting Cryptosporidium Removal . . . . . . . . . . . . . . . . 2 24 Exhibit 2.14: MF and UF Studies Documenting Virus Removal . . . . . . . . . . . . . . . . . . . . . . . . . . 2 25 Exhibit 2.15: Summary of Bag Filter Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 29 Exhibit 2.16: Bank Filtration Studies Measuring Coliform and Spore Removal . . . . . . . . . . . . . . . 2 32 Exhibit 2.17: NF Studies Documenting Microbial Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 46 Exhibit 2.18: NOM Removal Through NF Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 48 Exhibit 2.19: Bromide Removal Through NF Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 49 Exhibit 3.1: Base Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Exhibit 3.2: Chloramines for Secondary Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 Exhibit 3.3: Disinfection with Chlorine Dioxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4 Exhibit 3.4: UV Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 Exhibit 3.5: Water Quality Assumptions for UV Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 Exhibit 3.6 Number of Assumed UV Reactors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7 Exhibit 3.7: Ozone Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 8 Exhibit 3.8: Microfiltration and Ultrafiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 9 Exhibit 3.9: Bag and Cartridge Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 11 Exhibit 3.10: GAC Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 17 Exhibit 3.11: Nanofiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 19 Exhibit 4.1: Technologies Costed and Methodology Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Exhibit 4.2: Summary of Capital Cost Multiplier Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 Exhibit 4.3: Costs Indices Used in the Water and W/ W Cost Models . . . . . . . . . . . . . . . . . . . . . . 4 5 Exhibit 4.4: Unit and General Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6 Exhibit 4.5: Chemical Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6 Exhibit 4.6: Summary of Piloting Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 10 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 viii Exhibit 4.7: Summary of Land Cost Assumptions ( as a percentage of Capital Cost) . . . . . . . . . . . 4 11 Exhibit 4.8: Amortization Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 13 Exhibit 4.9: Chloramines as Secondary Disinfectant Cost Summary  Ammonia Dose = 0.15 mg/ L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 17 Exhibit 4.10: Chloramines as Secondary Disinfectant Cost Summary  Ammonia Dose = 0.55 mg/ L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 19 Exhibit 4.11: W/ W Cost Model Electricity Usage and Required Labor . . . . . . . . . . . . . . . . . . . . 4 24 Exhibit 4.12: Chlorine Dioxide Cost Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 25 Exhibit 4.13: UV Disinfection Cost Summary ( 40 mJ/ cm2 Without UPS) . . . . . . . . . . . . . . . . . . . 4 30 Exhibit 4.14: UV Disinfection Cost Summary ( 200 mJ/ cm2 Without UPS) . . . . . . . . . . . . . . . . . . 4 32 Exhibit 4.15: UV Disinfection Cost Summary ( 40 mJ/ cm2 with UPS) . . . . . . . . . . . . . . . . . . . . . . 4 34 Exhibit 4.16: UV Disinfection Cost Summary ( 200 mJ/ cm2 with UPS) . . . . . . . . . . . . . . . . . . . . . 4 36 Exhibit 4.17: Ozone Piloting Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 44 Exhibit 4.18: Ozonation O& M Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 45 Exhibit 4.19: Ozonation Cost Summary ( 0.5 log Cryptosporidium Inactivation) . . . . . . . . . . . . . 4 46 Exhibit 4.20: Ozonation Cost Summary ( 1.0 log Cryptosporidium Inactivation) . . . . . . . . . . . . . 4 48 Exhibit 4.21: Ozonation Cost Summary ( 2.0 log Cryptosporidium Inactivation) . . . . . . . . . . . . . 4 50 Exhibit 4.22: Summary of MF/ UF Vendor Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 53 Exhibit 4.23: Summary of MF/ UF Interstage Pumping Assumptions . . . . . . . . . . . . . . . . . . . . . . . 4 54 Exhibit 4.24: MF/ UF Land Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 56 Exhibit 4.25: Summary of MF/ UF Operator Training Assumptions . . . . . . . . . . . . . . . . . . . . . . . 4 57 Exhibit 4.26: Summary of Backwash Disposal Pipeline Assumptions . . . . . . . . . . . . . . . . . . . . . . 4 57 Exhibit 4.27: Summary of Membrane Replacement Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 Exhibit 4.28: Summary of MF/ UF Labor Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 Exhibit 4.29: Microfiltration/ Ultrafiltration Cost Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 Exhibit 4.30: Design Criteria for Bag and Cartridge Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 Exhibit 4.31: Summary of Bag and Cartridge Filter Pump Cost Data . . . . . . . . . . . . . . . . . . . . . . 4 65 Exhibit 4.32: Bag Filter Cost Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 68 Exhibit 4.33 Cartridge Filter Cost Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 Exhibit 4.34: Bank Filtration Cost Estimates for Three System Sizes . . . . . . . . . . . . . . . . . . . . . . 4 70 Exhibit 4.35: Second Stage Filtration Cost Estimates for Three System Sizes . . . . . . . . . . . . . . . . 4 70 Exhibit 4.36: Pre Sedimentation Cost Estimates for Three System Sizes . . . . . . . . . . . . . . . . . . . 4 71 Exhibit 4.37: Watershed Cost Categories for Three System Sizes . . . . . . . . . . . . . . . . . . . . . . . . 4 72 Exhibit 4.38: Summary of Filtration Improvement Design Assumptions . . . . . . . . . . . . . . . . . . . . . 4 74 Exhibit 4.39: Valve Actuator Horsepower Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 78 Exhibit 4.40: Capital Unit Costs for Combined Filter Performance Components . . . . . . . . . . . . . . 4 80 Exhibit 4.41: O& M Unit Costs for Combined Filter Performance Components . . . . . . . . . . . . . . 4 80 Exhibit 4.42: Percentages of Plants Using Each Filter Improvement Option . . . . . . . . . . . . . . . . . 4 81 Exhibit 4.43: Capital Cost Estimates for the Combined Filter Performance . . . . . . . . . . . . . . . . . . 4 82 Exhibit 4.44: O& M Costs for the Combined Filter Performance . . . . . . . . . . . . . . . . . . . . . . . . . 4 82 Exhibit 4.45: GAC Contactor Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 83 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 ix Exhibit 4.46: Summary of GAC Costs ( EBCT = 10 minutes, 360 day reactivation frequency) . . . . . . . . . . . . . . . . . . . . 4 94 Exhibit 4.47: Summary of GAC Costs ( EBCT = 20 minutes, 90 day reactivation frequency) . . . . . . . . . . . . . . . . . . . . . 4 96 Exhibit 4.48: Summary of GAC Costs ( EBCT = 20 minutes, 240 day reactivation frequency) . . . . . . . . . . . . . . . . . . . . 4 98 Exhibit 4.49: Percent Distribution of NF Equipment Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 101 Exhibit 4.50: Summary of NF Housing Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 103 Exhibit 4.51: NF Land Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 103 Exhibit 4.52: NF Operator Training Cost Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 104 Exhibit 4.53: Summary of NF Technical Labor Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 107 Exhibit 4.54: Nanofiltration Cost Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 108 Exhibit 4.55: Annualized Cost Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 111 Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 x List of Appendices Appendix A Very Small Systems Model Capital Cost Breakdown Summaries Appendix B Water Model Capital Cost Breakdown Summaries Appendix C W/ W Cost Model Capital Cost Breakdown Summaries Appendix D Technology Cost Curves Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 xi List of Acronyms AWWA American Water Works Association AWWARF American Water Works Association Research Foundation AWWSC American Water Works Service Company BAT Best Available Technology BCI building cost index BDOC biodegradable organic carbon BLS Bureau of Labor Statistics BV bed volume / C degrees Celsius CAP total capital costs CDC Centers for Disease Control and Prevention CFE combined filter effluent CFR Code of Federal Regulations CIP clean in place cm centimeter CT measured disinfectant residual × contact time CWS community water system D/ DBP disinfectant/ disinfection byproduct DBP disinfection byproduct DBPR Disinfectants and Disinfection Byproducts Rule DES designated flow DNA deoxyribonucleic acid DOC dissolved organic carbon E& I electrical and instrumentation EA economic analysis Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 xii EA environmental assessment EBCT empty bed contact time EIS environmental impact statement ENR Engineering News Record EPA United States Environmental Protection Agency ES effective size ESWTR Enhanced Surface Water Treatment Rule FACA Federal Advisory Committee Act FBRR Filter Backwash Recycling Rule fps feet per second ft feet ft2 ( sf or sq ft) square feet FTW filter to waste GAC granular activated carbon gfd gallons of filtrate per day per square foot of membrane area gpd gallons per day gpm gallons per minute GWUDI ground water under the direct influence of surface water HAA haloacetic acid HAA5 sum of five haloacetic acids HAA6 sum of six haloacetic acids HIV human immunodeficiency virus Hp horsepower HPC heterotrophic plate count hr hour HVAC heating, ventilation, and air conditioning i discount rate Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 xiii I& C instrumentation and controls ICR Information Collection Rule IESWTR Interim Enhanced Surface Water Treatment Rule in inch kgal thousand gallons kgpd thousand gallons per day kW kilowatt kWh kilowatt hour lb pound LOX liquid oxygen LP low pressure LPHO low pressure high output LPUV low pressure ultraviolet light LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule MCL maximum contaminant level MCLG maximum contaminant level goal M DBP microbial disinfection Byproduct MF microfiltration mg/ kg milligrams per kilogram µ g/ L micrograms per liter mg/ L milligrams per liter mgal million gallons MGD or mgd million gallons per day mJ milliJoules mJ/ cm2 milliJoules per square centimeter µ m micrometer Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 xiv mm millimeter MP medium pressure MRDL maximum residual disinfectant level MRDLG maximum residual disinfectant level goal MWCO molecular weight cut off MWDSC Metropolitan Water District of Southern California N number of years NDWAC National Drinking Water Advisory Council NF nanofiltration NIPDWR National Interim Primary Drinking Water Regulation nm nanometers NOM natural organic matter NPDWR National Primary Drinking Water Regulation NSF National Science Foundation NTNCWS nontransient noncommunity water system NTU nephelometric turbidity units O& M operations and maintenance OGWDW Office of Ground Water and Drinking Water OH& P overhead and profit OSHA Occupational Safety and Health Administration P& V pipes and valves PAC powder activated carbon PLC programmable logic controller POTW publicly owned treatment works ppb parts per billion ppm parts per million PPI Producer Price Index ( for Finished Goods) Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 xv PSA pressure swing absorption psi pounds per square inch psig pounds per square inch gauge PUV pulsed ultraviolet PVC polyvinyl chloride PWS public water supply RIA regulatory impact analysis RNA ribonucleic acid RO reverse osmosis SAB Science Advisory Board SCADA Supervisory Control and Data Acquisition scf standard cubic feet SDS simulated distribution system SDWA Safe Drinking Water Act sf ( ft2 or sq ft) square feet SOC soluble organic carbon SOC synthetic organic compound sq ft ( or sf or ft2) square feet SWAT surface water analytical tool SWTR Surface Water Treatment Rule TDH total dynamic head TDP Technology Design Panel TDS total dissolved solids THM trihalomethane THMFP trihalomethane formation potential TMP transmembrane pressure TNCWS transient noncommunity water system Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 xvi TOC total organic carbon TOX total organic halide TOXFP total organic halide formation potential TSS total suspended solids TTHM total trihalomethane TWG Technical Work Group UC uniformity coefficient UF ultrafiltration UPS uninterrupted power supply UV ultraviolet UVT ultraviolet transmittance UV 254 ultraviolet absorbance at 254 nm VSS Very Small Systems Best Available Technology Cost Document wk week WTP water treatment plant W/ W water and wastewater yr year Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 1 1. Introduction 1.1 Purpose of Technology and Cost Document This document provides information on costs and treatment effectiveness of technologies and treatment strategies available to public water systems ( PWSs) to remove or inactivate pathogenic microorganisms, specifically Cryptosporidium, and/ or reduce the formation of disinfection byproducts ( DBPs). This information is developed solely for use in conducting Economic Analyses ( EAs) for the proposed Stage 2 Disinfectants and Disinfection Byproducts Rule ( DBPR) and Long Term 2 Enhanced Surface Water Treatment Rule ( LT2ESWTR). Please note that the information provided by this document is of a general nature. It is not intended to guide PWSs in selecting or designing technologies for compliance with existing or proposed rules.

The proposed LT2ESWTR will require systems to provide additional Cryptosporidium treatment if Cryptosporidium concentrations in their source waters exceed specified levels. Cryptosporidium is resistant to chlorine but can be inactivated with certain alternative disinfectants or can be physically removed through filtration processes.

The proposed Stage 2 DBPR will require PWSs to reduce the formation of trihalomethanes ( THMs) or haloacetic acids ( HAAs) if they exceed specified levels. THMs and HAAs form primarily through reactions between chlorine and natural organic matter ( NOM). Their formation can be reduced with alternative disinfectants or disinfection practices or through increases in NOM removal prior to chlorine application.

Issues associated with microbial disinfection and the formation of DBPs are interwoven; PWSs should not undercut microbial protection in their efforts to reduce DBP levels. Several of the alternative disinfectants that systems could choose to reduce the formation of THMs and HAAs can provide increased protection against chlorine resistant pathogens like Cryptosporidium. For these reasons, PWSs should have the ability to make decisions regarding compliance strategies for the Stage 2 DBPR and LT2ESWTR at the same time. Consequently, the United States Environmental Protection Agency ( EPA) is developing these regulations as a paired rulemaking and is addressing compliance technologies for both rules in a single document.

The EAs for the LT2ESWTR and Stage 2 DBPR evaluate the total impact of a regulation in terms of costs associated with additional treatment requirements and benefits associated with reduced risk. This evaluation requires the following types of information:

° National occurrence of the regulated contaminant( s)

° Existing level of treatment for the contaminant provided by PWSs Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 2 ° Unit costs and efficacy of treatment strategies available for compliance with the proposed regulation ° Number and sizes of PWSs that will select a particular treatment strategy for regulatory compliance ° Benefits and costs resulting from changes to existing treatment This document supports the EA by describing the design criteria necessary for a technology to achieve a desired level of treatment and the cost associated with that technology as a function of the design criteria. Information on unit costs and treatment performance is critical to projecting technology usage stemming from a regulation and to evaluating national compliance costs and benefits. No information is given here on the national compliance costs ( that information is provided in the EA) or on the numbers of PWSs that will adopt various treatment strategies to comply with the proposed regulations.

Process design criteria for alternative disinfection strategies and DBP precursor removal technologies were developed in large part using water quality data gathered under the Information Collection Rule ( ICR) and best engineering judgement. Where appropriate, EPA used ICR data to generate statistics regarding water quality parameters that affect technology performance. These water quality statistics were used to estimate costs for technology options presented in this document. Costs were developed using EPA cost models, manufacturer price data, and recent literature. Unit prices and cost indices for model input were based upon vendor information, prevailing rates, and published values in the trade literature ( e. g., Engineering News Record, Bureau of Labor Statistics). These costs were reviewed by the Technical Work Group, which was convened by EPA to assist in the Stage 2 DBPR and LT2ESWTR regulatory development process. Subsequent revisions have also been made to respond to comments from outside reviewers, particularly the National Drinking Water Advisory Council ( NDWAC) and EPA's Science Advisory Board ( SAB).

1.2 Existing Regulations The following are existing regulations that address risks posed by microorganisms and DBPs in public water systems.

1.2.1 Surface Water Treatment Rule Under the Surface Water Treatment Rule ( SWTR), finalized in 1989, EPA set Maximum Contaminant Level Goals ( MCLGs) of zero for Giardia lamblia, viruses, and Legionella; and promulgated National Primary Drinking Water Regulations ( NPDWRs) for all PWSs using surface water or ground water under the direct influence of surface water ( GWUDI). Unfiltered systems were required to comply with the SWTR by 1991 and filtered systems by 1993. The SWTR includes treatment technique requirements for filtered and unfiltered systems that are intended to protect against Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 3 the adverse health effects of exposure to Giardia, viruses, and Legionella, as well as other pathogenic microorganisms ( 63 FR 69478 December 1998b). Briefly, those requirements include the following:

° Maintenance of a disinfectant residual in the distribution system ° Removal/ inactivation of 3 log ( 99.9 percent) for Giardia and 4 log ( 99.99 percent) for viruses ° Combined filter effluent turbidity performance standards ° Watershed protection and raw water quality requirements for unfiltered systems 1.2.2 Information Collection Rule The ICR is a monitoring and data reporting rule that was promulgated in 1996. The purpose of the ICR was to collect occurrence and treatment information to help evaluate the need for possible changes to the SWTR and microbial treatment practices and to help evaluate the need for future regulation of DBPs. The ICR provided EPA with information on the occurrence of pathogenic microorganisms, including Cryptosporidium, Giardia, and viruses, as well as the occurrence of DBPs and water quality parameters that impact DBP formation. The ICR also provided engineering data on how PWSs control such contaminants ( 65 FR 19046 April 2000).

1.2.3 Interim Enhanced Surface Water Treatment Rule The Interim Enhanced Surface Water Treatment Rule ( IESWTR) was finalized in December 1998 and applies only to surface water and GWUDI PWSs serving 10,000 or more people. The purposes of the IESWTR were to improve control of microbial pathogens, specifically Cryptosporidium and to address risk trade offs between pathogens and disinfection byproducts ( 65 FR 19046 April 2000). Key provisions of the rule include the following:

° MCLG of zero for Cryptosporidium ° 2 log ( 99 percent) Cryptosporidium removal requirements for systems that filter ° Strengthened combined filter effluent turbidity standards ° Requirements for individual filter turbidity monitoring ° Disinfection benchmark provisions to ascertain the level of microbial protection provided as systems take steps to comply with new DBP standards Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 4 ° Inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered systems ° Requirements for covers on new finished water reservoirs ° Requirements for sanitary surveys for all surface water and GWUDI systems, even those serving fewer than 10,000 people 1.2.4 Stage 1 Disinfectants and Disinfection Byproducts Rule The Stage 1 Disinfectants and Disinfection Byproducts Rule was promulgated in 1998. The Stage 1 DBPR applies to all PWSs that are community water systems ( CWSs) or non transient noncommunity water systems ( NTNCWSs) and that treat their water with a chemical disinfectant for either primary or secondary disinfection. In addition, certain requirements for chlorine dioxide apply to transient non community water systems ( TNCWSs). Surface water and GWUDI systems serving at least 10,000 people were required to comply with the Stage 1 DBPR by January 2002. All ground water systems, as well as surface water and GWUDI systems serving fewer than 10,000 people, must comply with the Stage 1 DBPR by January 2004.

The Stage 1 DBPR established the following provisions:

° Maximum residual disinfectant level goals ( MRDLGs) for chlorine, chloramines, and chlorine dioxide ° MCLGs for three trihalomethanes ( bromodichloromethane, dibromochloromethane, and bromoform), two haloacetic acids ( dichloroacetic acid and trichloroacetic acid), bromate, and chlorite ° Maximum residual disinfectant levels ( MRDL) for chlorine, chloramines, and chlorine dioxide ° MCLs for total trihalomethanes ( TTHM), five haloacetic acids ( HAA5), bromate, and chlorite The rule also includes monitoring, reporting, and public notification requirements for the listed compounds. EPA estimates that the rule will provide public health protection for an additional 20 million households not previously covered by drinking water rules for DBPs ( 65 FR 19046 April 2000). Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 5 1.2.5 Long Term 1 Enhanced Surface Water Treatment Rule The Long Term 1 Enhanced Surface Water Treatment Rule ( LT1ESWTR) ( 67 FR 1812 January 2002), finalized in January 2002, extends the requirements of the IESWTR to surface water and GWUDI systems serving fewer than 10,000 people.

1.2.6 Filter Backwash Recycling Rule The Filter Backwash Recycling Rule ( FBRR) ( 66 FR 31086 June 2001) regulates systems in which filter backwash is returned to the treatment process. The rule, promulgated in June 2001, applies to surface water and GWUDI systems that use direct or conventional filtration and recycle spent filter backwash water, sludge thickener supernatant, or liquids from dewatering processes. The rule requires that these recycled liquids be returned to a location such that all steps of a system's conventional or direct filtration process are employed. The rule also requires systems to notify the state that they practice recycling. Finally, systems must collect and maintain information for review by the state.

1.3 Public Health Concerns 1.3.1 Pathogenic Microorganisms In 1990, EPA's SAB, an independent panel of experts established by Congress, cited drinking water contamination as one of the most important environmental risks and indicated that diseasecausing microbial contaminants ( e. g., bacteria, protozoa, and viruses) are probably the greatest remaining health risk management challenge for drinking water suppliers ( EPA/ SAB 1990). Information on the number of waterborne disease outbreaks from the U. S. Centers for Disease Control and Prevention ( CDC) underscores this concern. CDC indicates that, between 1991 and 2000, 145 drinking water related disease outbreaks were reported, with more than 431,000 associated cases of disease ( This includes outbreaks in individual water systems, which are not PWSs. About 400,000 cases of illness were from one outbreak.) During this period, a number of agents were implicated as the cause, including protozoa, viruses, and bacteria.

Waterborne diseases are usually acute ( i. e., sudden onset and typically lasting a short time in healthy people), and most waterborne pathogens cause gastrointestinal illness, with diarrhea, abdominal discomfort, nausea, vomiting, and/ or other symptoms. Some waterborne pathogens cause, or are associated with, more serious disorders such as hepatitis, gastric cancer, peptic ulcers, myocarditis, swollen lymph glands, meningitis, encephalitis, and other diseases.

Cryptosporidium, a protozoan parasite, is of particular concern as a waterborne pathogen because it is highly resistant to inactivation by chlorine and chloramines. In addition, no therapeutic treatment currently exists for cryptosporidiosis, the infection caused by Cryptosporidium. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 6 Cryptosporidiosis usually causes 7 14 days of diarrhea, sometimes accompanied by a low grade fever, nausea, or abdominal cramps in healthy individuals ( Juranek 1995). It may, however, cause the death of individuals with compromised immune systems. In 1993, Cryptosporidium caused more than 400,000 people in Milwaukee to experience intestinal illness. More than 4,000 were hospitalized, and at least 50 deaths were attributed to the cryptosporidiosis outbreak. Nevada, Oregon, and Georgia have also experienced cryptosporidiosis outbreaks over the past several years.

Despite filtration and disinfection, Cryptosporidium oocysts have been found in filtered drinking water ( LeChevallier et al. 1991), and many of the individuals affected by waterborne disease outbreaks caused by Cryptosporidium were served by filtered surface water supplies ( Solo Gabriele and Neumeister 1996). Surface water systems that filter and disinfect may still be vulnerable to Cryptosporidium, depending on the source water quality and treatment effectiveness.

1.3.2 Disinfectants/ Disinfection Byproducts While the use of chemical disinfectants is highly effective in reducing the risk of waterborne disease, disinfectants are known to react with NOM to form byproducts that may pose a public health risk. In addition, the disinfectants themselves may pose a public health risk at high concentrations.

The assessment of public health risks from chlorination of drinking water currently relies on inherently difficult and incomplete empirical analysis. Nevertheless, while recognizing these uncertainties and taking into account the large number of people exposed to DBPs and the different potential health risks that may result from exposure to DBPs ( e. g., cancer and adverse reproductive and developmental effects), EPA believes that the weight of evidence represented by the available epidemiology and toxicology studies support a hazard concern and a protective public health approach to regulation.

1.4 Proposed Regulations 1.4.1 Long Term 2 Enhanced Surface Water Treatment Rule In September 2000, an Agreement in Principle was reached by EPA and members of the Stage 2 Microbial Disinfection Byproduct ( M DBP) Federal Advisory Committee Act ( FACA) Committee regarding the requirements of the proposed LT2ESWTR ( 65 FR 83015 December 2000). Under the agreement, the LT2ESWTR will require all surface water systems, including GWUDI, that serve at least 10,000 people to conduct two years of source water monitoring for Cryptosporidium. Conventional systems whose annual average Cryptosporidium concentrations are at least 0.075, 1.0, or 3.0 oocysts per liter would be required to achieve an additional 1, 2, or 2.5 logs, respectively, of Cryptosporidium removal or inactivation beyond conventional treatment. Systems could meet these additional treatment requirements through the use of various options including: enhanced filtration Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 7 performance, watershed control, alternative disinfectants, membranes, various types of filters, and demonstrations of performance.

1.4.2 Stage 2 Disinfectants/ Disinfection Byproducts Rule The Stage 2 DBPR, which will be proposed along with the LT2ESWTR, will apply to all CWSs and NTNCWSs that add a disinfectant other than ultraviolet ( UV) light or deliver disinfected water. Under the Stage 2 M DBP Agreement in Principle ( 65 FR 83015 December 2000), the Stage 2 DBPR will retain the MCLs of 80 : g/ L for TTHM and 60 : g/ L for HAA5 established by the Stage 1 DBPR. However, the Stage 2 DBPR will change the way compliance with these MCLs is determined. Under Stage 1, compliance with the TTHM and HAA5 MCLs is based on a running annual average of all monitoring points within a distribution system. Under the Stage 2 DBPR, compliance would be based on a locational running annual average, which means that the running annual average at each monitoring point within a distribution system would have to be less than the MCL. The Stage 2 DBPR would also require systems to conduct an initial distribution system evaluation which would identify the areas with the highest concentrations of TTHM and HAA5; compliance monitoring will be conducted at those locations.

1.5 Technologies Evaluated for the Control of Pathogens and Disinfection Byproducts Systems required to provide additional treatment for Cryptosporidium under the LT2ESWTR can use two basic mechanisms: inactivation and removal. While chlorine and chloramines are not effective against Cryptosporidium at doses used in drinking water treatment, chlorine dioxide, ozone, and UV light have been demonstrated to inactivate this pathogen. Chlorine dioxide and ozone generally require higher doses to inactivate Cryptosporidium than those necessary for Giardia and viruses; the use of these disinfectants is limited by the formation of regulated byproducts like chlorite and bromate. UV has been shown to achieve high levels of Cryptosporidium inactivation at relatively low doses but is currently not widely used in the United States for drinking water treatment. Nevertheless, EPA believes that ozone, chlorine dioxide, and UV are available to PWSs to inactivate Cryptosporidium. Consequently, EPA has evaluated these technologies in this document.

PWSs can increase the physical removal of Cryptosporidium in their treatment plants by using additional physical barriers like microfiltration ( MF) or bag and cartridge filtration. These technologies have been shown to achieve high log reductions of Cryptosporidium when properly designed and implemented. This document addresses Cryptosporidium removal.

Utilities can also take steps to reduce the concentration of Cryptosporidium entering the treatment plant through strategies such as watershed control, pre sedimentation basins, and bank Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 8 filtration. Costs for these technologies were obtained from the M DBP FACA Committee and are provided in Chapter 4. However, these costs were too uncertain to use in the EA for the LT2ESWTR.

Systems required to reduce the formation of TTHM and HAA5 for compliance with the Stage 2 DBPR can use two approaches. One approach is to reduce the use of free chlorine by switching to disinfectants that do not form, or form only low concentrations of, TTHM and HAA5. Such disinfectants include: chloramines, ozone, chlorine dioxide, and UV. Systems may also reduce free chlorine doses by using physical barriers like microfiltration; microfiltration removes more microorganisms so that less disinfection is needed. This document evaluates chloramines, ozone, chlorine dioxide, UV, and MF as alternative disinfection strategies for reducing TTHM and HAA5 formation. ( Note that several of these disinfection strategies were also evaluated for Cryptosporidium treatment as described above.)

The second approach for systems to reduce TTHM and HAA5 formation is to increase the removal of DBP precursors ( i. e., NOM) prior to disinfection. Systems can remove precursors by increasing coagulation dosages in a process termed enhanced coagulation, or softening, or by installing granular activated carbon ( GAC) or nanofiltration ( NF). For the purposes of this document, it was assumed that utilities will have already optimized coagulation or softening practices to meet the requirements of the Stage 1 DBPR. As a result, this document evaluates only GAC and NF as precursor removal strategies.

In summary, this document provides an analysis of the following technologies:

Alternative disinfection strategies ° Chloramination ° Chlorine dioxide ° Ultraviolet ( UV) light ° Ozone ° Microfiltration and ultrafiltration ° Bag and cartridge filters ° Bank filtration ° Second stage filtration ° Pre sedimentation basins Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 1 9 ° Watershed control ° Combined Filter Performance Alternative DBP precursor removal strategies ° Granular activated carbon adsorption ° Nanofiltration 1.6 Document Organization This remainder of this document contains the following sections:

Chapter 2  Technologies for DBP and Microbial Contaminant Control: Presents comprehensive discussions of all disinfection, Cryptosporidium removal, and DBP precursor removal strategies considered in this document. Includes technology descriptions, effectiveness of technologies for DBP precursor and/ or microbial control, and factors affecting the performance of each technology.

Chapter 3  Technology Design Criteria : Discusses the rationale behind development of the design criteria for which costs are presented in Chapter 4. Includes design approach, assumptions and additional factors ( e. g., residuals handling) which may impact design.

Chapter 4  Technology Costs: Presents capital, operations and maintenance, and total annualized costs for each disinfection strategy and DBP precursor removal technology considered. Also includes discussion of estimation methods ( e. g., cost models and vendor information).

Chapter 5  References: Provides a comprehensive bibliography of all literature used in the compilation of this document.

Appendices: Contain capital cost breakdown summaries for technologies for which cost models were used. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 1 2. Technologies for DBP and Microbial Contaminant Control 2.1 Introduction Public water systems may employ various treatment strategies to reduce chlorinated DBPs and to provide better physical removal or inactivation of Cryptosporidium for compliance with the proposed Stage 2 DBPR and LT2ESWTR. EPA considers the following treatment strategies as being available for compliance with these two proposed regulations:

Alternative disinfection strategies ° Chloramination ( section 2.2.1)

° Chlorine dioxide ( section 2.2.2)

° Ultraviolet light ( section 2.2.3)

° Ozone ( section 2.2.4)

° Microfiltration and ultrafiltration ( section 2.2.5)

° Bag and cartridge filtration ( section 2.2.6)

° Bank filtration ( section 2.2.7)

° Second stage filtration ( section 2.2.8)

° Pre sedimentation ( section 2.2.9)

° Watershed control ( section 2.2.10)

° Combined filter performance ( section 2.2.11)

DBP precursor removal strategies ° Granular activated carbon adsorption ( section 2.3.1)

° Nanofiltration ( section 2.3.2) Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 2 2.2 Alternative Disinfection Strategies 2.2.1 Chloramination Chloramines are formed by reactions of ammonia with aqueous chlorine. These reactions may result in the formation of monochloramine ( NH2Cl), dichloramine ( NHCl2) and trichloramine ( NCl3). The relative concentrations of these species depend upon the pH of the water and the relative proportion of chlorine and ammonia. At chlorine to ammonia mass ratios of 3: 1 to 5: 1 ( Cl2: NH3 N) and neutral pHs, conditions common to drinking water treatment, the principal chloramine species formed is monochloramine ( USEPA 1999b).

One of the least expensive methods for controlling DBP formation is the use of monochloramine, instead of free chlorine, to maintain a distribution system residual. After the appropriate free chlorine contact time, ammonia is added to quench the residual free chlorine and to retard DBP formation. This reduces the free chlorine contact time and, thus, DBP formation, without compromising microbial protection. The initial free chlorine contact time and chloramine together provide sufficient disinfection. A survey conducted by the American Water Works Association Research Foundation ( AWWARF) has shown that most of the utilities that changed disinfection practices to lower distribution system THM levels have done so by switching to chloramine as the secondary disinfectant ( McGuire 1989).

Systems that do not use free chlorine for primary disinfection ( e. g., that use ozone or UV light) must add chlorine prior to ammonia addition. For most systems, the free chlorine residual needs to be increased prior to the point of ammonia addition to maintain the desired chloramine residual in the distribution system. This can be accomplished by: 1) simultaneous addition of chlorine and ammonia ( after primary disinfection with free chlorine or ozone) or 2) the addition of ammonia after chlorine addition.

Further information, including case studies of systems converting from free chlorine to chloramine, is summarized in Optimizing Chloramine Treatment ( Kirmeyer et al. 1993). This reference supplies additional information on the reason( s) for switching to chloramine and contains information on chloramination changeover and start up procedures, nitrification, and impact on taste and odor.

<IP_ADDRESS> Efficacy Against Pathogens Chloramine is less effective than free chlorine for the disinfection of most pathogenic microorganisms. At pH 7 and below, monochloramine is approximately 200 times less effective than free chlorine for coliform inactivation under the same contact time, temperature, and pH conditions. For viruses and cysts, the combined chlorine forms ( e. g., monochloramine and dichloramine) are considerably less effective than free chlorine ( USEPA 1999b). Historical studies have found time Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 3 factors ( monochloramine contact time: free chlorine contact time) from 20: 1 to 80: 1 for the same bacterial inactivation efficiency. For the same conditions of contact time, temperature, and pH, combined chlorine ( monochloramine) doses are approximately 25 times higher than free chlorine for the same bacterial inactivation efficiency ( White 1999). There is evidence that dichloramine may be twice as effective as monochloramine; however, dichloramine is generally avoided because it contributes to taste and odor problems.

The Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources ( SWTR Guidance Manual   USEPA 1990) presents CT ( contact time multiplied by residual disinfectant concentration) values for multiple disinfectants, pathogens, pH and temperature ranges. Exhibit 2.1 compares CT requirements for chloramine with those of free chlorine over a range of temperature and pH values.

Exhibit 2.1: Comparison of CT Values for Free Chlorine and Chloramine Log Remova l Giardia Viruses < 1o C 10o C 20o C < 1o C 10o C 20o C Cl NH2Cl Cl NH2Cl Cl NH2Cl Cl NH2Cl Cl NH2Cl Cl NH2Cl 0.5 40 635 21 310 10 185

1 79 1270 42 615 21 370

2 158 2535 83 1230 41 735 6 1243 3 643 1 321 3 237 3800 125 1850 62 1100 9 2063 4 1067 2 534 Note:  Data not available. Source: USEPA 1990.

Exhibit 2.1 demonstrates that chloramine is relatively ineffective compared to free chlorine for Giardia and virus inactivation. In addition, chloramine is ineffective for inactivation of Cryptosporidium ( Peeters et al. 1989, Korich et al. 1990). Several studies have evaluated whether disinfection with ozone followed by chloramination ( Liyanage et al. 1997a, Driedger et al. 1999) has a synergistic effect on Cryptosporidium inactivation ( i. e., the inactivation achieved using both disinfectants combined is greater than what is expected for each of the disinfectants separately). The results of these studies are inconclusive but indicate that some synergism may exist for ozone/ chloramine applications. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 4 <IP_ADDRESS> DBP Formation The byproducts formed by chloramination, for the most part, are identical to those produced during chlorination and include THMs, HAAs, haloacetonitriles, and cyanogen chloride. With the possible exception of cyanogen chloride, chloramination does not preferentially form any of the halogenated DBPs compared to free chlorine. In fact, studies have demonstrated that chloramines produce much lower levels of DBPs than free chlorine ( Kirmeyer et al. 1993, Symons et al. 1996). This is the primary reason water systems implement chloramines for secondary disinfection rather than free chlorine.

The formation of DBPs resulting from chloramination is influenced by the following treatment variables ( Kirmeyer et al. 1993, Carlson and Hardy 1998):

° Contact time and chloramine dosage ° Point of ammonia application ° pH and temperature ° Total organic carbon ° Chlorine to ammonia ratio ° Mixing and reaction time for chloramine formation The point of ammonia application after chlorine addition generally impacts the length of time free chlorine reacts with NOM. For most plants using chlorine as a primary disinfectant, the point of ammonia application depends on disinfection requirements and goals. Once ammonia is added, the rate of DBP formation is significantly reduced ( Kirmeyer et al. 1993).

Within the range of chloramine residuals commonly used in the water industry ( 1 to 5 milligrams per liter ( mg/ L)), chloramine dose does not appear to be a significant factor in DBP formation; the chlorine to ammonia ratio appears to be more significant. TTHM concentrations remain quite low at chlorine to ammonia weight ratios less than 5: 1, then increase dramatically above the 5: 1 ratio ( Kirmeyer et al. 1993). Most utilities use chlorine to ammonia ratios of 3: 1 to 5: 1 because dichloramine and trichloramine form at higher ratios. These species are unstable and cause taste and odor problems. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 5 <IP_ADDRESS> Factors Affecting Performance When chlorine and ammonia are added simultaneously, good mixing can reduce the time free chlorine has to react with NOM. With complete mixing at neutral pHs ( 7 to 9) and temperatures of 20 to 25 degrees Celsius ( / C), the reaction of ammonia and chlorine to form monochloramine takes less than 3 seconds. This eliminates the free chlorine almost immediately and reduces the potential for DBP formation ( Kirmeyer et al. 1993). Efficient mixing and dispersion of chemicals ( chlorine and ammonia) at the point of addition determines the extent of free chlorine contact and, thus, substantially impacts the formation of DBPs.

As noted above, pH is important for rapid formation of chloramine. Symons et al. ( 1996) showed that DBP formation decreased with increasing pH. Exceptions to the trend are noted in some instances at pH 8, where Symons et al. noted that the complexity of chloramine chemistry may cause water specific responses.

Carlson and Hardy ( 1998) evaluated the effects of various water quality variables, such as pH, temperature, chlorine dosage, and total organic carbon on THM and HAA formation for waters from five utilities. Of the variables studied, the free chlorine contact time was found to be the most important in forming chlorinated DBPs. Chlorine contact time must be balanced to provide disinfection and to control byproduct formation. The type of DBP precursor was also found to be important. Based on this study, the authors proposed the concept of two sets of precursors: those that form DBPs quickly and those that form DBPs slowly. The precursor material that rapidly reacts with chlorine to form DBPs ( i. e. the quick formers) are of greater importance when chloramine is used to maintain a residual. These quick formers are less affected by reaction conditions than are the slow formers. Relatively consistent THM and HAA concentrations formed quickly after the addition of chlorine. Temperature, chlorine dosage, and pH had a greater effect on precursor materials that formed DBPs slowly.

White ( 1999) summarizes the effect of contact time and dose on the disinfection properties of chloramines. Generally, chloramines require much longer contact times than other chemical disinfectants ( e. g., free chlorine and ozone). This is one reason they are more suitable for secondary disinfection in the distribution system, where residence times can be several days. Chloramines are a less powerful oxidant than many other chemical disinfectants and can require substantially higher doses to achieve the same level of disinfection ( White 1999). Because longer contact times and higher doses are required for effective chloramine disinfection, residual stability is of major importance. Monochloramine, the preferred chloramine form, is the dominant species at pH levels greater than 5.5 and is essentially the only species present at pH levels around 7.5 ( Kirmeyer et al. 1993). Systems using chloramines for secondary disinfection should try to maintain a distribution system pH of approximately 7.5.

A primary concern for systems using chloramines is nitrification in the distribution system. Nitrification is a microbiological process by which free ammonia is converted to nitrite and nitrate. Ammonia oxidizing bacteria and nitrobacter, which are naturally present in distribution system biofilms Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 6 and may infiltrate leaking or corroding pipes, convert free ammonia to nitrite and ( in the presence of sufficient dissolved oxygen) nitrate, respectively. Among the effects of nitrification are a depletion of the chloramine residual and an increase in heterotrophic plate counts ( HPC) ( Kirmeyer et al. 1995). To prevent nitrification, it is important to optimize the chlorine: ammonia ratio and minimize free ammonia in the distribution system. Nitrification is most likely to occur in distribution system dead ends, areas of low demand, and storage tanks. As a result, the potential for nitrification can also be minimized by improving distribution system piping configurations ( e. g., looping to eliminate dead ends and increasing flow in low demand areas) and by increasing storage tank turnover.

2.2.2 Chlorine Dioxide Chlorine dioxide has been used for drinking water treatment in the United States for more than 50 years, primarily to control taste and odor problems. However, chlorine dioxide has received attention lately because of its potential application for Cryptosporidium inactivation ( Finch et al. 1995, Li et al. 1998) and for reduced formation of THMs or HAAs during disinfection ( White 1999). However, chlorine dioxide degrades to form chlorite and chlorate. Chlorite is considered to have public health implications and is a regulated DBP.

Chlorine dioxide cannot be transported because of its instability and explosiveness. Therefore, it is generated on site. The five common methods for producing chlorine dioxide are as follows: 1) sodium chlorite reaction with acid, 2) chorine solution reaction with chlorite solution, 3) chlorine gas reaction with chlorite solution, 4) reduction of sodium chlorate using hydrogen peroxide and concentrated sulfuric acid, and 5) chlorine gas reaction with solid chlorite ( White 1999). The yield, purity, and production capacities of chlorine dioxide vary for the five types of methods. The most common chlorine dioxide generation technique is chlorine solution reaction with chlorite solution. Chlorine dioxide dosages that can be used in drinking water treatment are constrained by regulatory limits on the production of chlorite and chlorine dioxide residual.

<IP_ADDRESS> Efficacy Against Pathogens The SWTR Guidance Manual presents CT values for inactivation of Giardia and viruses for both free chlorine and chlorine dioxide. The values indicate that chlorine dioxide is approximately four times more effective that chlorine for the inactivation of Giardia at most conditions. Chlorine, however, is more effective for the inactivation of viruses. Exhibit 2.2 summarizes CT values contained in the guidance manual. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 7 Exhibit 2.2: Comparison of CT Values for Free Chlorine and Chlorine Dioxide Log Remova l Giardia Viruses < 1o C 10o C 20o C < 1o C 10o C 20o C Cl ClO2 Cl ClO2 Cl ClO2 Cl ClO2 Cl ClO2 Cl ClO2 0.5 40 10 21 4 10 2.5

1 79 21 42 7.7 21 5

2 158 42 83 15 41 10 6 8.4 3 4.2 1 2.1 3 237 63 125 23 62 15 9 25.6 4 12.8 2 6.4 Note:  Data not available. Source: USEPA 1990.

Chlorine dioxide has been compared to other oxidants for inactivating Cryptosporidium ( Korich et al. 1990); chlorine dioxide and ozone are found to be more effective in inactivating Cryptosporidium compared to chlorine and monochloramine. However, unlike ozone, the degradation byproducts of chlorine dioxide do not contribute to the inactivation of Cryptosporidium ( Liyanage et al. 1997b). The American Water Works Service Company ( AWWSC) evaluated the effectiveness of chlorine dioxide for the inactivation of Cryptosporidium ( AWWSC 1998). AWWSC found that chlorine dioxide is effective for warm, high pH waters ( pH of approximately 8 and temperature around 20 degrees Celsius). Finch et al. ( 1995) summarized the chlorine dioxide research regarding the inactivation of Cryptosporidium. A summary of CT values for Cryptosporidium is presented in Exhibit 2.3.

Exhibit 2.3: Summary of Chlorine Dioxide CT Values for Cryptosporidium Inactivation Log Inactivation AWWSC From Summary by Finch et al. ( 1995) 10o C 20o C 1 99 48 60 2 257 115 80 3   140 Note:  Data not available. All values are for pH 8. Temperature for Finch et al. is unknown. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 8 Chlorine dioxide has also been proven effective for the inactivation of selected bacteria over a pH range of 3.0 to 8.0 ( Junli et al. 1997, White 1999) and is a stronger disinfectant than chlorine for bacteria, requiring lower CT values. Some of the bacteria evaluated in Junli et al. ( 1997) are E. coli ( A and B), Staphylococcus aureus, Sarcina, Chloropseudomonas, Bacillus subtilis, and Shigella dysenteriae.

<IP_ADDRESS> DBP Formation Studies have demonstrated that chlorine dioxide does not produce THMs ( White 1999); under proper generation conditions ( i. e., no excess chlorine), halogen substituted DBPs are not formed. The application of chlorine dioxide produces only a small amount of total organic halide ( TOX) ( Werdehoff and Singer, 1987). The use of chlorine dioxide aids in reducing the formation of TTHMs and HAAs by oxidizing precursors. By moving the point of chlorination downstream in the plant after coagulation, sedimentation, and filtration, the quantity of NOM is reduced. This results in a lower chlorine dosage during post chlorination of the water which, in turn, results in fewer THMs.

In normal pH ranges ( 6 to 9), chlorine dioxide undergoes a variety of oxidation reactions with NOM to form oxidized organic species, such as chlorinated, brominated, or polysubstituted organic byproducts and chlorite ( ClO2 ). Chlorite concentrations can account for up to 70 percent of the chlorine dioxide consumed ( American Water Works Association ( AWWA) 1999; Werdehoff and Singer 1987). Chlorite, and chlorate ( ClO3 ) are formed when chlorine dioxide is added to water. All three oxidized chlorine species ( chlorine dioxide, chlorite, and chlorate) are considered to have adverse health effects and are of concern in finished water ( AWWA 1999).

Chlorine dioxide may also facilitate a number of chlorine substitution reactions. Studies evaluating drinking water and NOM have shown that TOX concentration increases upon application of chlorine dioxide at normal treatment dosages ( AWWA 1999).

<IP_ADDRESS> Factors Affecting Performance Temperature dramatically affects Cryptosporidium inactivation by chlorine dioxide ( Li et al. 1998). At 1 oC, a 0.5 log inactivation is observed at a CT of 150 milligrams * minutes / liter ( mgmin L), compared to a 2.0 log inactivation for the same CT at 22" C. Chlorine dioxide can effectively inactivate bacteria over a pH range of 3.0 to 8.0. Because it is a more effective disinfectant for bacteria than free chlorine, lower CT values are required. Caution must be taken, however, when selecting the appropriate dose, as excessive dosages can lead to chlorite formation above permissible levels. Purity and generator yields are two of the most critical factors that effect chlorine dioxide use. Chlorine and the oxychlorine species ( i. e., chlorite and chlorate) are typically present in the impurities of chlorine dioxide ( White 1999). Therefore, the purity of the chlorine dioxide generated should be considered to avoid a violation of the chlorite maximum contaminant level ( MCL). Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 9 2.2.3 Ultraviolet Light The use of UV light for disinfection of drinking water has recently received much attention because of new developments regarding Cryptosporidium inactivation at low UV light doses ( Bukhari et al. 1999) and because it creates very few DBPs. Disinfection is accomplished by irradiating water with UV light. UV light is electromagnetic radiation between wavelengths of 100 and 400 nanometers ( nm). The specific range of UV wavelengths and the level of irradiance depend on the type of UV lamp system used. The effective germicidal wavelength range for most microorganisms is generally considered to be between 200 and 300 nm ( Malley 1998).

UV systems consist of UV reactors with an associated control panel. Commercial UV reactors used for drinking water applications are closed reactors containing UV lamps, quartz sleeves, UV intensity sensors, quartz sleeve wipers, and temperature sensors. UV lamps are housed within the quartz sleeves, which protect and insulate the lamps. Some reactors include automatic cleaning mechanisms to keep the quartz sleeves free of deposits that may form due to contact with the water. UV intensity sensors, flow meters, and in some cases, UV transmittance monitors are used to monitor dose delivery by the reactor.

UV lamps can be divided into two categories: continuous wave and pulsed wave. Currently, continuous wave UV lamps are most widely used for drinking water treatment. The types of continuous wave lamps are low pressure mercury vapor ( LP), low pressure high output ( LPHO), and medium pressure mercury vapor ( MP). " Pressure" refers to the pressure of mercury vapor within the lamp casing. A comparison of the LP, LPHO, and MP lamps is shown in Exhibit 2.4. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 10 Exhibit 2.4: Comparison of UV Lamps Parameter LP LPHO MP Germicidal UV light Monochromatic at 254 nm Monochromatic at 254 nm Polychromatic, including germicidal range ( 200  300nm) Mercury Vapor Pressure ( torr) Optimal at 0.007 Optimal at 0.007 100  10,000 Operating Temperature ( oC) Optimal at 40 130  200 600  900 Electrical Input ( W/ centimeter ( cm)) 0.5 1.5  10 50  150 Germicidal UV Output ( W/ cm) 0.2 0.5  3.5 5  30 Electrical to Germicidal UV Conversion Efficiency (%) 35  38 30  40 10  20 Arc Length ( cm) 10  150 10  150 5  75 Relative Number of Lamps Required for a Given Dose High Intermediate Low Lifetime ( hours( hrs)) 8,000  10,000 8,000  12,000 3,000  5,000 Source: EPA UV Disinfection Guidance Manual ( USEPA 2003).

The light emitted by LP and LPHO lamps is essentially monochromatic at 253.7 nm, which is in the range of the most germicidal wavelengths for microorganisms. MP lamps emit at a higher intensity than LP lamps but at a wide range of wavelengths. Therefore, LP and LPHO lamps convert power to germicidal light more efficiently than MP lamps. Theoretically, LPHO lamps have the same efficiency as LP lamps because they operate at similar vapor pressures. However in practice, LPHO lamp efficiency can be significantly lower when operating at different power settings. The main differences between LP and MP lamps, as shown in Exhibit 2.4, are the vapor pressure, operating temperatures, electrical input, and germicidal UV output.

Pulsed ultraviolet ( PUV) systems irradiate a high intensity UV light in flashes at approximately 50 flashes per second. PUV systems have limited operating experience on the full scale and are not costed in this document.

The UV lamp ballast controls the amount of electricity supplied to the lamp and should ensure a consistent and constant power delivery. Power supplies and ballasts can be supplied in many different configurations and are tailored to a unique lamp type and application. UV systems may use electronic ballasts, magnetic ballasts, or transformers.

UV intensity sensors are photosensitive detectors that measure the UV intensity at a point within the UV reactor. This intensity information is used to indicate dose delivery. Intensity sensors can be classified as wet or dry. Dry sensors monitor UV light through a monitoring window whereas wet UV intensity sensors are in direct contact with the water flowing through the reactor. Monitoring Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 11 windows and the wetted ends of the wet sensors can become fouled over time and require cleaning, similar to quartz sleeves.

The lamp cleaning mechanism used for a UV system depends on the lamp type, system size, and fouling potential of the water. Both manual and automatic cleaning regimes have been developed. Manual cleaning is primarily used for smaller systems with relatively few sleeves and lower fouling potential. Automatic cleaning approaches may be classified as flush and rinse systems, mechanical wipers, or physical chemical wipers. LPHO systems typically use flush and rinse systems, and MP systems typically use wipers because the higher lamp temperatures accelerate fouling under certain water qualities. The cleaning frequency of the lamps is a function of the lamp temperature and the concentration of dissolved organic and inorganic species that can cause lamp fouling.

<IP_ADDRESS> Efficacy Against Pathogens When UV light is applied to a microorganism, deoxyribonucleic acid ( DNA) and ribonucleic acid ( RNA) absorb the light energy and their structure is altered, thereby interfering with replication of the microbe. The UV dose necessary for inactivation of microorganisms varies from species to species and across microorganism classifications. Inactivation of microorganisms increases with increasing UV dose, although it does not always follow the typical log linear relationship.

Of the pathogens of interest in drinking water, viruses are most resistant to UV disinfection, followed by bacteria and protozoa. Exhibit 2.5 presents UV dose requirements for inactivation of Cryptosporidium, Giardia, and viruses ( as derived in the USEPA UV Disinfection Guidance Manual, Appendix B). The UV dose requirements presented in Exhibit 2.5 are the minimum required; operational UV doses will likely be two to four times higher after application of a safety factor.

Exhibit 2.5: UV Dose Requirements for Inactivation of Cryptosporidium, Giardia, and Viruses During Validation Testing Log Inactivation 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Cryptosporidium 1.6 2.5 3.9 5.8 8.5 11.7

Giardia 1.5 2.1 3.0 5.2 7.7 10.8

Virus 39.4 58.1 79.1 100.1 120.7 142.6 163.1 186.0 Note: All values presented in mJ / cm2 Source: USEPA UV Disinfection Guidance Manual, Appendix B. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 12 Based on the analysis presented in Appendix B of the EPA UV Disinfection Guidance Manual, the sensitivities of Giardia and Cryptosporidium to UV disinfection are very similar; viruses, however, are more difficult to inactivate. Battigelli et al. ( 1993) performed bench scale UV collimated beam experiments to determine the relationship between UV dose and inactivation of Hepatitis A virus ( strain HM 175), coxsackievirus type B 5, rotavirus strain SA 11, and bacteriophages MS 2 and fX174. MS 2 bacteriophage required the highest dose of 25 milliJoules per square centimeter ( mJ/ cm2) for less than 1 log inactivation. With the other viruses, 4 log inactivation is achieved at doses ranging between 16 and 42 mJ/ cm2. The most UV resistant viruses of concern in drinking water are adenovirus Type 40 and Type 41. Meng and Gerba ( 1996) report a dose of 23.6 to 30 mJ/ cm2 for a 1 log inactivation in adenovirus and a dose of 111.8 to 124 mJ/ cm2 for 4 log inactivation.

Because microbes that have been exposed to UV light still retain metabolic functions, some are able to repair the damage done by UV light and regain infectivity. Repair of UV light induced DNA damage includes photoreactivation and dark repair ( Knudson 1985). Photoreactivation ( or photorepair) is an enzymatic DNA repair mechanism wherein the DNA damage is repaired when exposed to light between 310 and 490 nm. Dark repair is an enzymatic repair mechanism that does not require light. Not all microorganisms contain the necessary cellular mechanisms to repair UV damaged DNA. One study has shown that Cryptosporidium contains the capability to undergo some DNA repair. However, even though the DNA was repaired, infectivity was not restored ( Oguma et al. 2001). Another study, by Shin et al. ( 2001), did not observe photorepair with Cryptosporidium parvum. Linden et al. ( 2002a) did not observe photoreactivation or dark repair of Giardia at UV doses typical for UV disinfection applications ( 16 and 40 mJ/ cm2). However, unpublished data from the same study showed Giardia reactivation in light and dark conditions at very low UV doses ( 0.5 mJ/ cm2; Linden 2002a). Shaban et al. ( 1997) found that viruses also lack the repair enzymes necessary for photoreactivation. However, photorepair of viral DNA can occur using the enzyme systems of their host cells. Knudson ( 1985) found that bacteria were able to repair in light and dark conditions, suggesting that bacteria may have the enzymes necessary for photorepair and dark repair. As such, photoreactivation is generally limited to bacteria.

E. coli and HPC inactivation by UV light are well documented, particularly with respect to wastewater disinfection ( Chang et al. 1985, Wilson et al. 1992). Photoreactivation of bacteria has been documented with E. coli, S. aureus, and coliphage, while dark repair has been documented with S. aureus and coliphage ( Shaban et al. 1997). One study ( Knudsen, 1985) examined two different strains of E. coli: one that had the enzymes necessary for repair ( B/ R strain) and one that lacked the necessary repair enzymes ( recA uvr strain). The difference in UV dose needed for 1 log inactivation of the strain capable of repair was over two orders of magnitude higher than the dose needed for 1 log inactivation of the repair deficient strain, indicating that dark repair impacts the UV dose response of microorganisms. Unlike bacteria, viruses do not have the enzymes necessary for dark repair. However, viruses can repair in the host cell using the host cells' enzymes ( Rauth 1965). Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 13 <IP_ADDRESS> DBP Formation Several studies have been conducted to determine if DBPs are formed as a result of UV light irradiation. Zheng et al. ( 1999) found that TTHM and HAA9 formation did not increase when UV light was applied to chlorinated water at a dose of 100 mJ/ cm2. Linden et al. ( 1998) investigated DBP formation in wastewater secondary effluent that is irradiated with LP and MP UV lamps and found no evidence of photochemical reactions or DBP formation. Malley et al. ( 1996) examined the effects of post UV disinfection ( chlorination and chloramination) on DBP formation and found no significant impact by UV on DBP levels formed by chemical disinfection. Malley et al. ( 1995) also observed no significant change in THM, HAA, bromate, or other halogenated DBP concentrations following disinfection with UV light. A study performed with filtered drinking water indicated no significant change in aldehydes, carboxylic acids, or TOX ( Kashinkunti et al., 2003). However, a low conversion rate ( about one percent) of nitrate to nitrite by UV light has been observed ( von Sonntag and Schuchman, 1992). Conversion of nitrate to nitrite is lower with LP lamps than with MP lamps because the UV absorbance of nitrate is higher below 240 nm than it is at 254 nm. Due to the low conversion rate of nitrate to nitrite by UV light, it is of minimal concern in drinking water applications. Several studies have shown low level formation of non regulated DBPs ( e. g., aldehydes) as a result of applying UV light to wastewater and raw drinking water sources. The difference in results can be attributed to the difference in water quality, most notably the higher concentration of organic material in raw waters and wastewaters.

<IP_ADDRESS> Factors Affecting Performance Particle content can impact UV disinfection performance. Particles may absorb and scatter light, thereby reducing the UV intensity delivered to the microorganisms. Particle associated microbes also may be shielded from UV light, effectively reducing disinfection performance. Particles in source waters are diverse in composition and size and include large molecules, microbes, clay particles, algae, and flocs.

Recent research by Linden et al. ( 2002b) indicates that the UV dose response of microorganisms added to filtered drinking waters was not altered by variation in turbidity that met regulatory requirements. For unfiltered raw waters, Passantino and Malley ( 2001) found that source water turbidity up to 10 nephelometric turbidity units ( NTU) did not impact the UV dose response of separately added ( seeded) organisms. In these experiments, however, organisms were added to waters containing various levels of treated or natural turbidity. Therefore, it was not possible to examine microbes associated with particles in their natural or treated states. Consequently, these drinking water studies can only suggest the impact of turbidity on dose response as it relates to the impact of UV light scattering by particles. The studies cannot predict the effect on UV disinfection of microbes attaching to particles. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 14 UV absorbance, often exerted by dissolved organic matter in drinking water applications, affects the design of the UV system. Water that absorbs a significant amount of UV light ( i. e., high UV absorbance and low transmittance) will need a higher UV irradiance or longer exposure to achieve the same level of inactivation as water with lower UV absorbance. As UV absorbance increases, the intensity throughout the reactor decreases for a given lamp configuration. This results in a reduction in delivered dose and measured UV intensity for a given lamp output. In a situation with a fixed UV output, lower UV absorbance values result in more UV energy being available in the water column, causing a higher log inactivation of microorganisms than a water with a higher UV absorbance. For systems with high levels of dissolved organic matter ( high UV absorbance), it is more efficient to apply UV light after unit processes that remove organic matter.

Several chemicals used in water treatment processes can increase the UV absorbance of water ( e. g., Iron ( Fe+ 3)). However, some oxidants ( including ozone) can reduce the UV absorbance ( APHA et al. 1998). Water treatment processes upstream of the UV reactors can be operated to control and reduce UV absorbance, thereby optimizing the design and costs of the UV system.

Depending on the water quality ( e. g., dissolved ions, hardness, alkalinity, and pH levels) and lamp temperature, scale can form on the UV lamps. MP lamps tend to scale more easily than LP and LPHO lamps because the operating temperature of MP lamps is considerably higher. Scale can reduce the UV energy being transmitted through the lamp sleeve into the water and potentially compromise disinfection. Lamp cleaning is an important consideration for the design of UV systems to control lamp scaling and to ensure consistent disinfection performance. Water pH may also affect lamp scale formation, but inactivation of microorganisms with UV light is not pH dependent ( Malley 1998).

UV inactivation of microorganisms is not directly affected by water temperature. However, the performance of UV lamps is dependent on the lamp temperature. Most UV lamps have sleeves ( usually made of quartz) that insulate the lamps, maintain optimal temperature, and provide maximum irradiance. If the lamp temperature deviates from optimal, the lamp irradiance will be reduced. This is especially true with LP UV lamps in cold waters ( Mackey et al. 2000). Therefore, the water temperature variation should be considered when designing a low pressure system. However, MP lamps have a significantly higher operating temperature compared to the water temperature. Thus, as long as an insulating quartz sleeve is in place, the water temperature has little effect on the operating temperature of the MP lamp and MP lamp performance.

Hydraulics are an important part of the UV equipment. Ideally, the UV reactor should exhibit plug flow characteristics. In plug flow, water that enters the reactor is completely mixed axially and moves through the reactor as a single plug with no dispersion in the direction of flow. However, " real world" hydraulics in a full scale reactor are never plug flow. UV reactors are typically equipped with baffles to reduce the amount of short circuiting through the reactor and to encourage plug flow, although these baffles can increase head loss through the reactor. Staggered lamp arrays also promote mixing within the reactor and minimize short circuiting of flow. Alternatively, vortex mixers can be used to increase lamp spacing, thereby reducing head loss through the reactor. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 15 Inlet and outlet conditions can have a significant impact on reactor hydrodynamics. Straight inlet conditions with gradual changes in cross sectional area can be used to develop flow for optimal dose delivery. Straight inlets with no sharp bends or sudden changes in cross sectional area optimize dose deliveries.

It may be necessary to characterize the reactor flow regime in order to determine the level of disinfection provided. Tracer tests are typically not feasible because the hydraulic residence time in the reactor is too short ( i. e., on the order of seconds or fractions of a second). However, hydraulic models are available to understand the behavior of the UV reactor.

2.2.4 Ozone In recent years, the use of ozone technology in water treatment has dramatically increased. In 1991, approximately 40 water treatment plants in the United States, each serving more than 10,000 people, utilized ozone ( Langlais et al. 1991). As of April 1998, this number had grown to 264 operating plants ( Rice et al. 1999). The main reasons for the escalating use of ozonation are the strong oxidizing properties of ozone and the absence of the formation of chlorinated DBPs during disinfection ( however, bromated DPBs are formed).

In water, ozone reacts with hydroxide ions ( OH) to form hydroxyl free radicals ( HO1); therefore, pH is a very important parameter in determining the extent and rate of contaminant oxidation. Oxidation with ozone is also influenced by other water quality characteristics, such as temperature, alkalinity, and the concentration of reduced chemical species ( i. e., iron and manganese). Other important considerations include ozone dose and contact time.

Ozone is commonly added to raw water ( pre ozonation) or settled water. To take advantage of ozone's ability to improve flocculation and NOM removal, ozone must be applied to raw water. Application of ozone to raw or settled water is considered to be equally effective for primary disinfection. However, larger doses may be necessary for raw water application due to the higher NOM and particulate matter concentrations.

There are two basic types of ozone generation equipment: liquid oxygen based systems and airbased systems. Liquid oxygen feed systems are relatively simple ( e. g., there is no air pretreatment equipment), less capital intensive, and yield a higher ozone concentration than air based systems. The liquid oxygen feed system components include a storage tank, an evaporator to convert the liquid to a gas, filters to remove impurities, and pressure regulators to limit the gas pressure to the ozone generators.

Air fed systems require air pretreatment equipment to prevent damage to the ozone generator. Air needs to be dry, free of contaminants, and with a dew point between  50" and  60" C. Air Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 16 pretreatment equipment consists of compressors, after coolers ( optional), refrigerant dryers, desiccant dryers, air filters, and pressure regulators. Power consumption is higher for air feed systems ( 8 12 kWh/ lb O3) than for oxygen feed systems ( 4 8 kWh/ lb O3). Exhibit 2.6 presents a comparison of the advantages and disadvantages of the two types of ozonation systems ( USEPA 1999b).

Exhibit 2.6: Comparison of Air and Liquid Oxygen Systems System Advantages Disadvantages Air Commonly used equipment Proven technology Suitable for small and large systems More energy consumed per ozone volume produced Extensive gas handling equipment required Maximum ozone concentration of 1 5 % Higher power consumption Fairly complicated technology Liquid Oxygen Less equipment required Simple to operate and maintain Suitable for small and large systems Can store excess oxygen to meet peak demands Higher ozone concentration ( 14 18%) Approximately doubles ozone production for same generator Lower power consumption Variable liquid oxygen costs Storage of oxygen onsite ( i. e., safety concerns) Loss of liquid oxygen in storage when not in use Oxygen resistant materials required Ozone is usually applied in one of three flow configurations: 1) co current ( ozone and water flowing in the same direction), 2) counter current ( ozone and water flowing in the opposite direction), or 3) alternating co current/ counter current. Ozone application systems include fine bubble diffusers, injectors/ static mixers, and turbine mixers ( Langlais et al. 1991). The fine bubble diffuser system is the most common and offers high ozone transfer rates, process flexibility, operational simplicity, and no moving parts. The injector/ static mixer system applies ozone in an in line or a sidestream configuration. Ozone is injected under negative pressure, created by a venturi section, and then mixed to enhance dispersion of ozone in the water stream. The turbine mixer systems feed ozone in the contactor and mix ozone with the water in the contactor. The turbine mixer can either project outside of the ozone contactor or be submerged.

Hoigne and Bader ( 1976) described ozone decomposition in water. Once ozone enters solution, it follows one of two reaction pathways: 1) direct oxidation, which is slow and selective in its oxidation of organic compounds, and 2) autodecomposition to the hydroxyl free radical ( HO°), which is extremely fast and nonselective. The hydroxyl free radical is scavenged by carbonate and bicarbonate ions, commonly measured as alkalinity, to form carbonate and bicarbonate free radicals. These radicals do not affect the organic reactions. The hydroxyl radicals produced by the autodecomposition react with organics and other radicals to reform hydroxyl radical in an autocatalytic process. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 17 The stability of dissolved ozone is affected by pH, ultraviolet light, ozone concentration, and the concentration of radical scavengers ( Langlais et al. 1991). Conditions of low pH favor the direct oxidation pathway, and high pH conditions favor the autodecomposition pathway described earlier. At pH levels between 3 and 6, the ozone is present primarily in its molecular form ( O3), and direct oxidation dominates. However, as the pH rises, the autodecomposition of ozone to produce the hydroxyl free radical ( HO°) becomes increasingly rapid. At pH levels greater than 10, the conversion of molecular O3 to HO° is virtually instantaneous. In general, better disinfection would be expected at lower pHs, since free hydroxyl radicals are short lived compared to molecular ozone. Studies have shown that increasing the temperature from 0" to 30" C reduces the solubility of ozone and increases its decomposition rate ( Kinman 1975).

<IP_ADDRESS> Efficacy Against Pathogens Ozone is one of the most potent biocides used in water treatment. It is effective against a wide range of pathogenic microorganisms including bacteria, viruses, and protozoa. Ozone shows greater efficiency inactivating most types of pathogenic microorganisms than chlorine, chloramine, and chlorine dioxide ( Clark et al. 1994). This is demonstrated by the CT values found in the SWTR Guidance Manual presented in Exhibit 2.7. The resistance of pathogenic microorganisms to ozone increases in the following order: bacteria, viruses, protozoa ( Camel and Bermond 1999).

Exhibit 2.7: Comparison of CT Values for Free Chlorine and Ozone Log Remova l Giardia Viruses < 1o C 10o C 20o C < 1o C 10o C 20o C Cl O3 Cl O3 Cl O3 Cl O3 Cl O3 Cl O3 0.5 40 0.48 21 0.23 10 0.12

1 79 0.97 42 0.48 21 0.24

2 158 1.9 83 0.95 41 0.48 6 0.9 3 0.5 1 0.25 3 237 2.9 125 1.43 62 0.72 9 1.4 4 0.8 2 0.4 Note:  Data not available Source: USEPA ( 1990)

Small concentrations of ozone are usually effective against bacteria. E. Coli levels were reduced by 4 log ( 99.99 percent removal) in less than one minute at an initial ozone concentration of 9 micrograms per liter ( µ g/ L) ( Wuhrmann and Meyrath 1955). Legionella pneumophila levels were reduced by 2 log ( 99 percent removal) in less than five minutes at an initial ozone concentration of 0.21 milligrams per liter ( mg/ L) ( Domingue et al. 1988). Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 18 Typically, viruses are more resistant to ozone than bacteria, although ozone is still effective against viruses. Ozone dosages of 0.2 to 1.5 mg/ L consistently achieved 2 log inactivation of poliomyelitis viruses with a contact time of 40 seconds ( Katzenelson et al. 1974). Katzenelson et al. ( 1974) also observed that poliomyelitis inactivation increased to nearly 5 log at a dose of 1.5 mg/ L and a contact time of approximately 100 seconds. Coxsackie virus inactivation is more than 5 log with an initial ozone dosage of 1.45 mg/ L ( Keller et al. 1974). The sensitivity of human rotavirus to ozone was found to be similar to that of coxsackie virus ( Vaughn et al. 1987).

Protozoan cysts are more resistant to ozone than bacteria and viruses. Data available for inactivation of Cryptosporidium oocysts suggest that, among protozoans, this pathogen is the most resistant to ozone ( Peeters et al. 1989; Langlais et al. 1990).

Ozone inactivation kinetics of Cryptosporidium are evaluated by Gyurek et al. ( 1999). The observed inactivation behavior of Cryptosporidium by ozone is characterized by a " tailing off" effect. At 22" C and a 5 minute contact time, an initial ozone residual of 1.2 mg/ L was required to provide 2 log inactivation. For contact times less than 5 minutes, a relatively small increase in the applied contact time significantly decreases the required initial ozone residual; however, for contact times greater that 10 minutes an increase in the applied contact time provides a negligible decrease in the required initial ozone residual. Hence, the influence of contact time on the inactivation kinetics decreases as Cryptosporidium is progressively exposed to ozone.

CT values for ozone inactivation of Cryptosporidium are still under development. Initial studies have demonstrated that CT values may be as much as 25 times higher than those required for Giardia ( Rennecker et al. 1999). These preliminary studies also demonstrate that CT requirements for Cryptosporidium inactivation increase by an average factor of approximately three for every 10" C decrease in temperature. A summary of reported ozonation requirements for 2 log inactivation of Cryptosporidium oocysts is presented in Exhibit 2.8. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 19 Exhibit 2.8: Reported Ozonation Requirements for 2 log Inactivation of Cryptosporidium Oocysts Experimental Protocol Initial Ozone Residual ( mg/ L) Temperature ( 0C) Contact Time ( min) CT ( mg min/ L) Reference Batch liquid, batch ozone 0.77 0.51 Ambient 6 8 4.6 4.0 Peeters et al. 1989 Batch liquid, continuous gas 1.0 25 5 10 5 10 Korich et al. 1990 Batch liquid, batch ozone 0.50 0.50 7 22 18 7.8 9.0 3.9 Finch et al. 1993 Flow through contactor, continuous gas 22 25 7.4 5.5 Owens et al. 1994 Batch liquid, batch ozone 0.7 22 3.2 3.2 Gyurek et al. 1999 Note: Owens et al. do not report residual dose.

<IP_ADDRESS> DBP Formation Ozone does not produce chlorinated DBPs; however, through the oxidation of natural organic precursor materials, ozone can alter the reactions between chlorine and NOM and affect the formation of chlorinated DBPs when chlorine is added downstream. Ozonation of natural waters produces aldehydes, haloketones, ketoacids, carboxylic acids, and other types of biodegradable organic material which must be adequately controlled ( often with a granular media biofilter).

Ozonation often increases the biodegradability of NOM in the treated water. Increasing biodegradability could be beneficial if a biological filtration process follows the ozonation step. A biological filtration step can remove the biodegradable fraction of NOM, increasing organic precursor removal. Biological filters remove NOM by using it as a substrate. Biological filtration can be employed on adsorptive media, such as GAC, and/ or non adsorptive media, such as sand and anthracite. Conversely, if the biodegradable fraction is not removed, it can increase the regrowth of microorganisms in the distribution system.

Haag and Hoigne ( 1983) have shown that ozone oxidizes bromide to form hypobromous acid and hypobromite ( HOBr and OBr) under water treatment conditions. Hypobromite was found to be further oxidized to bromate or to a species that regenerates bromide, whereas HOBr reacts with NOM to form brominated organic byproducts in waters containing bromide. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 20 Changes in pH can have a dramatic effect on the concentrations of HOBr and OBr and, therefore, the species of byproducts formed. An increase in pH increases the relative concentration of Br, which, in turn, leads to increased bromate formation. Reduced pH levels are often accompanied by a reduction in bromate concentrations; the lower pH enhances formation of bromoform and other organic brominated DBPs.

Krasner et al. ( 1989) found that an ozone residual is necessary to produce detectable levels of bromate. Siddiqui and Amy ( 1993) found that the bromoform concentration first increased then diminished at higher dosages. Song et al. ( 1995) demonstrated that lower ozone dosage and longer contact time should produce less bromate than higher dosages and shorter contact times.

Halogenated organic compounds are formed when NOM reacts with free chlorine or free bromine. Free bromine can be formed in ozone disinfection whenever bromide is present in the raw water source. The level of brominated byproducts formed during oxidation is dependent on the concentration of bromide in the raw water source and/ or the relative amount of bromide present compared to organic precursors.

Ozonation followed by chlorination has been observed to produce higher levels of haloketones than chlorination alone ( Jacangelo et al. 1989b). Chloral hydrate occurs primarily as a result of chlorination, although ozonation followed by chlorination has been observed to increase levels beyond those observed with chlorination only. Ozonation followed by chlorination or chloramination can increase chloropicrin levels above those observed with chlorination or chloramination alone. Ozonation followed by chloramination has been observed to increase cyanogen chloride levels beyond those observed with chloramination only. Cyanogen bromide, the brominated analog of cyanogen chloride, has been detected after ozonation of water containing high bromide levels ( McGuire et al. 1990).

Much less is known about non halogenated disinfection byproducts than the halogenated organic compounds. Among the major ozonation byproducts, aldehydes and carboxylic acids have the highest concentrations ( Glaze et al. 1993). Ozonation followed by chlorination has been found to yield the highest levels of acetaldehyde and formaldehyde. In addition, ozonation prior to chloramination is shown to produce more of these aldehydes than chloramination alone. Najm and Krasner ( 1995) report that the formation of ketoacids is proportional to the amount of dissolved organic carbon ( DOC) in the water. Ketoacid concentrations are largely unaffected by bromide concentration.

Ammonia addition has been used to limit the formation of some ozonation byproducts. In one study ( Siddiqui and Amy 1993), bromoform concentrations decrease by approximately 30 percent when ammonia is added at a NH3 to ozone ratio of 0.25 mg/ mg. The reason for this reduction is because HOBr reacts with ammonia to form bromamines, presumably making HOBr unavailable for reaction with NOM.

Conflicting results of ammonia addition on bromate formation have been observed ( Glaze et al. 1993, Krasner et al. 1993). Siddiqui et al. ( 1995) explained the percentage of bromate reduction upon Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 21 adding ammonia is more dependent upon pH and bromide concentration than on ammonia concentration ( Siddiqui et al. 1995). High bromide levels trap more oxidizing equivalents to give higher bromine yields and scavenge more radicals, thus reducing the radical processes that may cause bromate formation. Siddiqui et al. ( 1995) demonstrated that ( at similar ammonia concentrations) bromate formation decreased by more than 80 percent upon increasing the bromide concentration from 0.1 to 1.0 mg/ L.

<IP_ADDRESS> Factors Affecting Performance Ozone decays rapidly at high pH and warm temperatures. Krasner et al. ( 1993) noted that as the ozonation pH decreases, the required dose to meet CT requirements of the IESWTR drops and less bromate is formed. For one of the waters evaluated during bromide spiking experiments, bromate concentrations ranged from 24 to 68 µ g/ L at pH 8. For the same water, bromate concentrations ranged from less than 5 to 7 µ g/ L when the pH was decreased to 6. Better disinfection is expected at pH levels between 6 and 8 where molecular ozone dominates.

Temperature and alkalinity also affect formation of byproducts during ozonation. Increased temperature will increase the levels of bromate, bromoform, and total organic bromide. It also increases the decomposition of ozone. Conversely, increasing alkalinity has been shown to reduce the formation of bromoform and total organic bromide and increase the formation of bromate. Bicarbonate scavenges OH radicals, suggesting that the OH radical may play a role in the formation of brominated species by affecting the level of HOBr, which is presumed to be an active species for total organic bromide formation ( Glaze et al. 1993).

Total organic carbon ( TOC) concentration can have significant impacts on Cryptosporidium CT requirements. It has been demonstrated that ozone to TOC ratios greater than 1 are required for Cryptosporidium inactivation; whereas ozone to TOC ratios are typically less than 0.5 for Giardia inactivation. As previously discussed, temperature can also drastically affect the solubility, decomposition rate and biocidal effectiveness of ozone. Exhibit 2.9 presents CT requirements for Cryptosporidium inactivation at multiple temperatures and for inactivation ranging from 0.5 to 3 log. Exhibit 2.9 also compares the Cryptosporidium CT requirements with those of Giardia and presents the ratio of the Cryptosporidium requirement to the Giardia requirement. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 22 Exhibit 2.9: CT Considerations for Cryptosporidium Inactivation Log Inactivation Crypto CT at Temperature ( C) 1 Giardia CT at Temperature ( C) 2 Multiplier at Temperature ( C) 3 1 ° 13 ° 22 ° 1 ° 13 ° 22 ° 1 ° 13 ° 22 ° 0.5 6.00 2.00 0.60 0.48 0.19 0.10 12.5 10.6 5.8 1.0 12.00 4.00 1.50 0.97 0.38 0.21 12.4 10.4 7.2 1.5 24.00 8.00 3.00 1.50 0.58 0.31 16.0 13.9 9.6 2.0 40.00 11.00 4.40 1.90 0.76 0.42 21.1 14.5 10.6 2.5 45.00 15.00 6.00 2.40 0.95 0.52 18.8 15.7 11.5 3.0 62.00 22.00 8.00 2.90 1.14 0.62 21.4 19.3 12.8 1 Values reported to be acceptable for a pH range of 6 to 9. 2 Giardia CT required numbers are based upon the CT table included in the SWTR Guidance Manual. 3 Multiplier = Crypto CT at a given temperature / Giardia CT at the same temperature.

Source: Summary from Finch 1999.

2.2.5 Microfiltration and Ultrafiltration Membranes act as selective barriers, allowing some constituents to pass through while blocking the passage of others. The movement of these constituents across a membrane requires a driving force ( i. e., to overcome the potential difference across the membrane). Only pressure driven processes are discussed in this document due to their feasibility for DBP precursor and microbial control and their popularity in the drinking water field.

There are four categories of pressure driven membrane processes: microfiltration, ultrafiltration ( UF), nanofiltration, and reverse osmosis ( RO). Low pressure membrane processes, MF and UF, are typically applied for the removal of particulate and microbial contaminants and can be operated under positive or negative ( i. e., vacuum) pressure. Positive pressure systems typically operate between 3 and 40 pounds per square inch ( psi), whereas vacuum systems operate between  3 and  12 psi. RO and NF are typically applied for the removal of dissolved contaminants, including both inorganic and organic compounds. These processes operate at pressures significantly greater than the applied pressure in MF and UF processes, between 100 and 150 psi. Desalination applications can operate at pressures as high as 1,200 to 1,500 psi.

The ability of a membrane to remove a particular contaminant is influenced by its molecular weight cut off ( MWCO) or pore size. MWCO is a manufacturer specification that refers to the molecular mass of a macrosolute ( e. g., glycol or protein) for which a membrane has a retention capacity greater than 90 percent. The pore size refers to the diameter of the micropores on the membrane surface. The true pore size is difficult to measure, and, as a result, membrane manufacturers typically use some measure of performance to categorize the pore size of a membrane. The nominal pore size is typically based upon a given percent removal of a marker ( e. g., microsphere) of a known diameter. The absolute pore size is typically characterized as the minimum diameter above which 100 percent of a Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 23 0.001 µ 0.01 µ 0. 1 µ 1.0 µ 10 µ 100 µ 1000 µ Dissolved Organics Bacteria Sand Cysts Viruses Salts Colloids Media Filtration Microfiltration Ultrafiltration Nanofiltration Reverse Osmosis marker of a specific size is removed by the membrane. Exhibit 2.10 presents the MWCO/ pore size ranges for membrane processes, as well as the relative size of common drinking water contaminants.

MF and UF are primarily used for particle and microbial removal, either following granular media filtration or as a replacement for media filters. Chemical disinfection may be required, depending upon the approach of the State regulatory agency and the class of membrane used ( i. e., MF or UF). MF pore sizes are generally too large for virus removal and many States require a minimum 0.5 log chemical inactivation as part of a multiple barrier approach to disinfection.

The major components of a typical MF or UF membrane system include cartridge filters, low pressure feed pumps, membrane modules, high pressure backwash pumps, a chemical cleaning system, a chlorination feed system, and a concentrate handling and disposal system.

Exhibit 2.10: Pressure Driven Membrane Separation Spectrum Note: µ = Microns.

<IP_ADDRESS> Efficacy Against Pathogens MF and UF have shown excellent capabilities in turbidity, particulate matter, and microbial removal. MF and UF processes remove contaminants through physical straining of the feed water as it passes through the membrane. In this respect, microbial contaminants that are larger than a given membrane pore will be retained and prevented from entering the treated water. Since the size and Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 24 shape of microorganisms varies among species and since the size and shape of membrane pores varies among membrane types, the removal of a particular microorganism by MF and UF may vary. Many States have adopted disinfection log removal credits for MF and UF processes. States grant removal credits on a case by case basis for up to 3 log Giardia removal and 4 log virus removal. However, virus removal credits are typically 0.5 log or less due to the smaller size of viruses relative to MF/ UF pores.

MF and UF offer disinfection capabilities that are much improved over conventional media filtration. Exhibits 2.11 through 2.14 summarize observed removals of bacteria, Giardia, Cryptosporidium, and viruses, respectively.

Exhibit 2.11: MF and UF Studies Documenting Bacteria Removal Reference Process Membrane Pore Size Bacteria Type Log Removal Hofmann et al. ( 1998) MF 150,000 to 200,000 Daltons HPC, coliforms, thermotolerant coliforms, SSRC 2.5 to 3.5 Jacangelo et al. ( 1997) MF 100,000 Daltons P. Aeruginosa > 8.7*

Jacangelo et al. ( 1997) MF 0.2 : m P. Aeruginosa > 8.2*

Jacangelo et al. ( 1997) MF 0.2 : m Coliforms > 1.8*

Jacangelo et al. ( 1997) MF 0.2 : m E. Coli > 7.8*

Jacangelo et al. ( 1997) MF 0.2 : m HPC > 1.8*

Clair et al. ( 1997) MF 0.2 : m HPC 2.4 Clair et al. ( 1997) MF 0.2 : m Total Coliforms > 3 Glucina et al. ( 1997) MF 0.2 : m HPC and total Coliforms > 3 Glucina et al. ( 1997) UF 100,000 Daltons Total Coliforms > 3 Jacangelo et al. ( 1997) UF 100,000 Daltons Coliforms > 2.1*

Jacangelo et al. ( 1997) UF 100,000 Daltons E. Coli > 7.8*

Luitweiler ( 1991) MF  HPC 1.7 Jacangelo et al. ( 1991) UF  Total Coliforms > 3 Heneghan and Clark ( 1991) UF  HPC > 3.4 Jacangelo et al. ( 1989a) UF  HPC 2.8 Note: * Indicates removal to detection limit.  Data not available. Technologies and Costs for Control of Microbial Contaminants and Disinfection Byproducts June 2003 2 25 Exhibit 2.12: MF and UF Studies Documenting Giardia Removal Reference Process Membrane Pore Size Log Removal Scheider et al. ( 1999) MF 0.2 : m > 4.8 Scheider et al. ( 1999) MF 0.1 : m > 4.8*

Scheider et al. ( 1999) MF 0.1 : m > 4.8*

Trussel et al. ( 1998) MF 0.2 : m > 5.1*

Jacangelo et al. ( 1997) MF 0.2 : m > 5.2*

Jacangelo et al. ( 1997) MF 0.2 : m > 6.8*

Hagen ( 1998) UF 100,000 Daltons > 8*

Trussel et al. ( 1998) UF 100,000 Daltons > 5.1*

Jacangelo et al. ( 1997) UF 100,000 Daltons > 5.2*

Jacangelo et al. ( 1997) UF 100,000 Daltons > 6.8*

Jacangelo et al. ( 1991) UF   > 4*

Jacangelo et al. ( 1989a) UF 100,000 Daltons > 5*

Note: * Indicates removal to detection limit.  Data not available.