Performance Characteristics of Pollutants along the Longitudinal Profile of a Subsurface Flow Constructed Wetland Domestic Sewage Treatment Plant in the University of Lagos, Nigeria

Abstract

The paper reports the findings of a research work carried out to examine the performance and efficiency of a subsurface constructed wetland (SSFCW) for the treatment of domestic sewage in the University of Lagos (Unilag), Nigeria. The removal patterns and efficiencies of the physical, chemical and biological sewage pollutants parameters of domestic waste water generated within Unilag community by the SSFCW were studied. The wastewater was sampled and analysed along the SSFCW from influent (point1) to effluent (point 11). Total Dissolved Solids (TDS) reduced from 471 mg/l to 11.85 mg/l (97.48%), Turbidity reduced from 108.75 HTU to 0.05HTU (99.95%), Manganese reduced from 6.05 mg/l to 0.61 mg/ (89.92%), Nitrate reduced from 27.5 mg/l to 2.0 mg/l (92.73%), Sulphate reduced from 48.5 mg/l to 28 mg/l (42.27%), Iron reduced from 1.13 mg/l to 0.03 mg/l (97.35%), BOD reduced from 73.14 mg/l to 12.8 mg/l (82.5%), and E-coli reduced from 874 MPN/100 ml to 0.15 MPN/100 ml (99.98%). On the other hand, Dissolved Oxygen content increased along the SSFCW from 3.14 mg/l to 7.49 mg/l (138.54%) while the pH improved from slightly acid level of 6.49 to slightly above neutral level of 7.05 (9.3%). All the parameters at effluent point are within the Nigerian Federal Environmental Protection Agency (FEPA) acceptable standard. The study concludes that the SSFCW is a cheap, efficient and appropriate technology for the treatment of domestic sewage under tropical conditions .