The rate of removal of microbial pollutants along a series of constructed wetlands for treating wastewater in Covenant University, Ota, Nigeria were monitored from inlet to the discharge point into river Atuara and at 300 m upstream and downstream. The microbiological test results analysed were those of most probable number (MPN) of coliforms (
), coliform counts in cfu/100 ml, staphylococcus (cfu/ml), salmonella (cfu/ml), salmonella and shigella (cfu/ml), total viable count (cfu/ml) and fungi (cfu/ml). Exponential and linear models were used for the MPN trend. The exponential model fitted the trend better than the linear model having correlation coefficients of 0.954 and 0.814 respectively. Linear models fitted to the other contaminants resulted in correlations ranging from 0.958 to 0.994. It can be concluded that rate of removal of pollutants is proportional to the area covered by macrophytes in the wetland. These models were also used to predict adequacy of the constructed wetland to treat wastewater.
Keywords: contaminant, constructed wetland, wastewater, modelling, linear, exponential, treatment, predicted record