Constructed wetland relies on the removal or degradation of contaminants aswater moves through the media, using physical, chemical and biological processesfor water treatment. However, the performances of these systems depend on the site characteristics, sources water quality and the process conditions applied.Therefore, this study focused on analyzing the potential of constructed wetland for removal of organic matter, nutrients and pathogens from pre-treated water.Horizontal subsurface flow constructed wetlands (HSSFCWs) are being used worldwide to treat wastewater from a variety of sources.
An extensive literature review was conducted to update the current state of scientific knowledge on the performance of constructed wetlands for domestic wastewater treatment. This study were carried out on horizontal subsurface flow constructed wetlands in Qarawit Bani-Zeid village. Nine perforated pipes were placed in constructed wetland to take samples every two weeks over the study period (7months). Three pipes were placed after 1.5 m from the inlet of constructed wetland, another three pipes were placed in the middle of constructed wetland after 25m from the inlet of the constructed wetland, and 3pipes were placed 1.5m from the outlet of constructed wetland. Effluents were analyzed for biological oxygen demand (BOD), Chemical oxygen demand (COD), total khejldahl nitrogen (TKN), Nitrate (NO3--N), total dissolved solids (TDS), total suspended solids (TSS), pH, phosphate (PO43--P), electrical conductivity (EC) and fecal coliform (FC).
COD removal of 47%, BOD removal of 46.3%, TKN removal of 27%, NO3--N removal was BDL, PO43--P removal of 25.8%, sulphate removal of 46%, TSS removal of 65%, and (FC) removal of 98.8% were achieved by the constructed wetlands in Qarawit Bani-Zeid village. The dissolved oxygen (DO) of wastewater at each pipe in constructed wetland was close to zero. The TDS and fecal coliform (FC) in the effluent of the constructed wetland were 1052 mg/L 2628CFU/100mL respectively.
The constructed wetland was efficient in terms of COD and BOD removal and achieved the Palestinian standards for using treated effluent for reuse and discharge to wades. But, in terms of TSS and fecal coliform the constructed wetland didn't achieve those standards.
Evapotranspiration in the constructed wetland was measured by two methods, the first one was by a mini pilot of constructed wetland (plastic barrel), and the second one was by calculating the evapotranspiration in the constructed wetland itself by calculating the difference between influent and effluent flows, which was considered as water lost through evapotranspiration. The water lost through evapotranspiration calculated by the two methods was identical of around 20% of the influent flow.