Polishing of an aerobically pre-treated domestic sewage by constructed wetlands in Qarawit Bani-Zeid village
Beesan J. Bhais, دكتور نضال محمود
كلية الدراسات العليا-جامعة بيرزيت · فلسطين
Constructed wetland relies on the removal or degradation of contaminants as watermovesthroughthemedia,usingphysical,chemicalandbiologicalprocesses for water treatment. However, the performances of these systems depend on the site characteristics, sources water quality and the process conditions applied. Therefore,thisstudyfocusedonanalyzingthepotentialofconstructedwetlandfor 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 wastewatertreatment. This study were carried outon horizontal subsurface flow constructed wetlands in Qarawit Bani-Zeid village. Nineperforated pipes were placed in constructed wetland to takesamples every two weeks overthe study period (7months).Threepipes were placed after 1.5m from the inlet of constructed wetland, another three pipes were placed in the middle of constructed wetland after 25m from the inlet ofthe constructed wetland, and 3pipes were placed 1.5m from the outlet of constructed wetland. Effluents were analyzed forbiological oxygen demand(BOD), Chemical oxygen demand (COD), total khejldahlnitrogen (TKN),Nitrate(NO3--N),total dissolved solids (TDS), total suspended solids (TSS), pH,phosphate(PO43--P),electrical conductivity (EC)and fecal coliform(FC). VCODremovalof47%, BODremovalof46.3%,TKNremovalof27%,NO3--Nremoval was BDL, PO43--Premoval of 25.8%, sulphate removal of 46%, TSSremoval of65%, and (FC)removal of98.8%wereachievedbytheconstructedwetlandsin Qarawit Bani-Zeid village.The dissolved oxygen(DO) of wastewater at each pipein constructed wetland was close tozero. The TDS and fecal coliform (FC) in the effluentof the constructed wetland were 1052mg/L2628CFU/100mLrespectively.The constructed wetland was efficient in terms of COD and BODremovaland achieved the Palestinian standards for using treated effluent for reuse and discharge to wades. But, in terms ofTSS 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 bya mini pilot of constructed wetland (plastic barrel), andthe second one was bycalculatingthe evapotranspiration in the constructed wetlanditself by calculatingthe difference between influentand effluentflows, which was considered as water lostthroughevapotranspiration. The water lost through evapotranspiration calculated by the two methods was identical ofaround 20% of the influent flow.