ABSTRACT
The physicochemical and bacteriological qualities of effluents from WUPA Sewage Treatment Plant, Abuja were determined within the duration of twelve weeks. Grab method of wastewater sampling was used while sampling for the analysis. The sampling and analysis were carried out between May and September, 2015. Samples were collected at the inlet to the treatment plant (SCP 1), outlet of aeration tank (SCP 7C-2), outlet of sedimentation tank (SCP 8C-3), effluent outlet of the treatment plant (SCP 4), 10m upstream and 10m downstream of the receiving water body (River WUPA). Parameters analyzed included; biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), nitrate as nitrogen (NO3-N), nitrite as nitrogen (NO2-N), ammonium as nitrogen (NH4-N), dissolved oxygen (DO), chloride (CL-), sulfate (SO4-), faecal coliform (FC), total coliform count (TCC), pH and electrical conductivity (EC). The results of the sample analysis showed that the average removal efficiencies of the treatment plant in terms of BOD5 and COD were 92% and 83%% respectively, while the average removal efficiency for TSS was 89%. The dissolved oxygen (DO), nitrate (NO3-N) and nitrite (NO2-N) concentration of the effluent were observed to have increased by an average of 46%, 61% and 72% respectively relative to the inlet values. The average removal efficiencies for ammonium as N (NH4-N), CL- and SO4- were 58%, 19% and 30% respectively and the bacteriological contamination of the wastewater was averagely removed by 93% and 92% for faecal coliform (FC) and total coliform count (TCC) respectively. The pH and electrical conductivity (EC) were varied by 3% and 11% respectively. The study revealed that there was no adverse impact of the effluent water on the receiving water body (river WUPA) in terms of physiochemical parameters as the treated effluent from the facility conformed to the specified discharge limits for WHO (2007) and NESREA (2011), but in terms of the bacteriological parameters; values of the total coliform count (TCC) and faecal coliform (FC) were observed to be higher than that of the river at both upstream and downstream sections, which necessitates the development of a maintenance plan for the treatment plant with emphasis on proper maintenance of the unit processes of the treatment plant and UV treating the effluent properly before discharge into the receiving water body. A simple mathematical model was developed for BOD5 and TSS using mathematical analysis and the relationship obtained are as shown below: Y = 0.4218x2 - 19.6070x + 126.08; where Y = BOD5 (mg/l), x = Hydraulic retention time (Hr.) and Y = 0.6471x2 - 23.3510x + 146.91; where Y = TSS (mg/l), x = Hydraulic retention time (Hr.).