Effect of Seasonal Variation on Performance of Conventional Wastewater Treatment System

Abstract

Many studies have focused on wastewater treatment however, little attention has been given to effect of seasonal variation to wastewater treatment. The purpose of this study was to determine the seasonal differences of wastewater treatment that employs screens, trickling filters and oxidation ponds. This was achieved by sampling and analyses of water samples from four different points during the dry and wet seasons of the year 2013. Water samples were taken from influent point, primary pond effluent, trickling filter effluent and final effluent. Gravimetric method was used in determining Total Suspended Solids (TSS) and Total Dissolved Solids (TDS). The BOD5 technique and the COD digestion method were used for determination of Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) respectively while the temperature, pH and conductivity were measured using respective meters. Analysis of Variance showed that there was significant difference (p < 0.05) in all the parameters quantified at all the points of treatment during the two seasons. The results showed that BOD and COD both reduced from one point to the next during the two seasons of study. The TSS levels increased after primary pond effluent undergoing treatment at the trickling filter and the temperature also increased after the trickling filter effluent undergoing treatment at oxidation ponds. The levels of conductivity and TDS decreased from one treatment stage to the next during dry season but during the wet season the levels of these parameters increased from one stage to the next except that the levels reduced after the primary pond effluent underwent treatment at the trickling filter. The various stages of wastewater treatment plant under study were effective during the two seasons however, wet season recorded lower figures for most of the parameters.