EFFICIENCY OF UNIVERSITY OF ELDORET SEWAGE TREATMENT SYSTEM USING BIOLOGICAL INDICATORS

Abstract

At the University of Eldoret, wastewater is treated using sewage treatment ponds. These ponds were constructed to cater for a few students when the university was a Teacher’s Training College. Since then, the treatment ponds have never been expanded despite the ever rising population of the university and therefore creating the need for evaluation of the ponds’ efficiency. In this study, macro-invertebrates pollution tolerance index and selected physicochemical parameters were used to evaluate the efficiency of the University of Eldoret sewage treatment ponds. Wastewater samples were collectedmonthly in triplicates and transported to the laboratory for a period of six months. Nitrite, nitrate, dissolved reactive phosphorus and BOD were determined in the laboratory using standard methods and procedures. Temperature, pH, DO and conductivity were measured in situ monthly for a period of six months. Macro-invertebrates were collected monthly in plastic containers and preserved in 70 % alcohol and taken to the laboratory for identification for a period of six months. Data on physicochemical parameters was subjected to, One-way ANOVA test to determine (pond variation) for sampling spots and principle component analysis to determine metabolic processes in the sewage treatment ponds. The results of one way ANOVA test demonstrated that temperature (p≤0.001), pH (p≤0.002), DO (P≤0.001), conductivity (p≤0.003), BOD (P≤0.022), nitrates (p≤0.04) and nitrites (p=0.003) varied significantly among ponds except dissolved reactive phosphorus (p≥0.822) and TSS (p≥0.992) did not vary significantly. Principle Component Analysis results indicated three major components were extracted from water quality data. Component 1 was controlled by DO, pH BOD and temperature with loading values; 0.894, 0.865, 0.824 and 0.778 respectively. Component 2 was controlled by conductivity, TSS and phosphates with loading values; 0.85, 0.811 and 0.739 respectively while component 3 was controlled by nitrates and nitrites with loading values; 0.718 and 0.715 respectively. Pollution Tolerance Index resultsrated wastewater of the ponds as poor with range of values between 7.7 and 11, suggesting inefficiency of the sewage treatment ponds in wastewater restoration. It is therefore recommended that the sewage treatment system to be expanded and accumulated sludge to be disposed after every two to three years hence to improve its performance in wastewater restoration.