Potential of Horizontal Subsurface-Flow Constructed Wetlands for Polishing of Treated Sewages

AbstractConstructed wetlands (CWs) are increasingly being applied for wastewater treatment and as pretreatment before artificial recharge of the effluents. Three horizontal subsurface-flow CWs were operated in parallel for almost 7 months and fed with three types of treated effluents to analyze enhancement of water quality at an average hydraulic retention time (HRT) of 1.3 days. The wastewater effluents analyzed in this study were an on-site anaerobically pretreated sewage at an Al-Mazra'a house, tertiary effluent at Al-Bireh City, and secondary effluent at the Birzeit University campus in Palestine. The average dissolved organic carbon (DOC) removal of 48, 50, and 47%, chemical oxygen demand (COD) removal of 55, 45, and 50%, biochemical oxygen demand (BOD) removal of 57, 38, and 60%, ammonia-nitrogen (NH4+-N) removal of 96, 90, and 97%, nitrate-nitrogen (NO3−-N) removal of 88, 94, and 93%, total nitrogen (TN) removal of 72, 70, and 71%, phosphate (PO43−) removal of 63, 61, and 57%, total suspended solid...