PROPOSED MODEL FOR WASTEWATER TREATMENT IN LAHORE USING CONSTRUCTED WETLANDS

In developing countries, large quantities of wastewater are disposed into water bodies without any treatment. Process complexity, high energy consumption, lack of highly skilled operators, and high capital and operational costs have made the conventional treatment methods difficult to adopt in these countries. Constructed wetlands (CW) are engineered systems that are designed and constructed to utilize the natural processes, involving wetland vegetation, soils and the associated microbial assemblages to assist in treating wastewaters. It is a low cost and energy efficient option for a developing countries like Pakistan. In this study, the application of CW for the treatment of wastewater of Lahore city has been investigated in this study. A local plant, Reed (Phragmites) was evaluated (using a lab scale wetland model) for its potential use in constructed wetland. Removal efficiency of the system was evaluated at different detention times ranging from 1 to -5 days. The results demonstrated 90% removal for TSS, 75% removal for BOD and 80% removal for COD at 5 days detention time. The mean effluent concentration of 10 mg/L, 40 mg/L and 68 mg/L for TSS, BOD, and COD, respectively was obtained at 5-days detention period, thus complying with effluent standards of Pakistan. The results of the study support the suitability of CW for Lahore, and also motivate for detailed pilot plant studies.