Constructed Wetland for Wastewater Treatment and Reuse: A Case Study of Developing Country

Abstract

Treatment performance of a pilot-scale constructed wetland (CW) commissioned in a developing country was evaluated for removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), ammonia-nitrogen (NH4-N), ortho-phosphate (PO4-P), total coliforms (TC) and faecal coliforms (FC) from pretreated domestic wastewater. Monitoring of wetland influent and effluent was carried out for a period of 8 months. Treatment effectiveness was evaluated which indicated good mean removal efficiencies; BOD (50%), COD (44%), TSS (78%), NH4-N (49%), PO4-P (52%), TC (93%) and FC (98%). The studied constructed wetland reduced concentrations of all contaminants present in the pretreated wastewater. The performance of contaminant removal varied throughout the monitoring period. The treated effluent from the constructed wetland can be reused for landscape irrigation. Few samples of BOD and TSS were within the US EPA reuse limits which shows that the constructed wetland can effectively treat the wastewater and fulfill the reuse limits occasionally. Faecal coliforms were not fully removed but the limits for reuse were achieved occasionally. For developing countries like Pakistan with limited technological advancement and energy problems, constructed wetlands which have a zero or very low energy requirement can be used in the treatment trains.