Residuals from treating acid mine drainage can be used as effective, inexpensive adsorbents for agricultural and wastewater discharges, a new study by scientists from the U.S. Geological Survey Leetown Science Center has found.
When acid mine drainage is remediated it is neutralized with a base such as limestone or lime and an iron-rich sludge is formed. The new study published in the Journal Water, Air, and Soil Pollution shows the sludge can efficiently remove phosphorus from agricultural and municipal wastewaters.
The phosphorus that has been adsorbed by the mine drainage residuals can later be stripped from the residuals and recycled into fertilizer, the study says.
"This wonderful result shows the inventive application of some very sophisticated environmental chemistry to create a new life cycle for what otherwise would have been some problematic waste products," said US Geological Survey Director Marcia McNutt in a December 17, 2012 announcement to media about the study. "It sets the bar high for future studies in environmental remediation."
Acid mine drainage is produced whenever sulfide minerals associated with coal and metal deposits are exposed to air and moisture. The resulting acid and dissolved metals are toxic to most forms of aquatic life.
The study, Fixed Bed Sorption of Phosphorus from Wastewater Using Iron Oxide-Based Media Derived from Acid Mine Drainage, is authored by P. L. Sibrell and T. W. Tucker.
Lead author Sibrell said the findings create a “win-win” situation as the mine drainage residuals can be regenerated and reused for a number of additional treatment cycles.
"As environmental scientists, we kind of hesitate to use this analogy, but it really is like killing two birds with one stone," Sibrell said in the study’s announcement. "This new technology could reduce or eliminate the need to dispose of acid mine drainage sludge, instead making that same sludge useful in addressing the urgent need to reduce the amount of phosphorus going into aquatic ecosystems.”
Untreated acid mine drainage has impacted more than 5,000 miles of streams in the Appalachian region, with associated economic impacts of millions of lost dollars in the tourism and sport fishing industries.
Excess phosphorus releases to the environment from agricultural and municipal wastewaters have resulted in significant impairment of aquatic ecosystems such as the Chesapeake Bay and other bodies of water worldwide.
Current technology for the removal of phosphorus from wastewater consists of addition of aluminum or iron salts to precipitate and adsorb phosphorus, but this is too expensive for the low concentrations and high volumes often encountered in many wastewaters. This new technology provides a more efficient and cost-effective option.
REPORT : http://link.springer.com/article/10.1007/s11270-012-1262-x/fulltext.html