Evaluation of the Effect of Biological Nutrient Removal (BNR) on Wastewater Quality

Abstract

Industrial wastewater, particularly brewery wastewater contains high-strength organic, inorganic, and biological compounds which are harmful to the environment. Different technologies such are employed towards treating brewery wastewater before discharge into water bodies, but biological method has proven to be more environmental-friendly, cost-effective and easier to operate. This research project assessed the impact of biological nutrient removal (BNR) on wastewater quality, and it involved laboratory scale sequencing batch reactor (SBR), operated in a cyclic aerobic-anaerobic set-up inoculated with activated sludge to remove orthophosphates and nitrate compounds. Raw brewery wastewater samples were collected from Awo-Omama brewery plant of Nigerian Breweries Plc, Imo State, Nigeria. They were analyzed using standard methods described by American Public Health Association (APHA) to determine the removal efficacies of orthophosphates (PO₄^3-), ammoniacal-nitrogen (NH₃-N), total Kjeldahl nitrogen (TKN), total nitrogen (TN), total organic nitrogen (TON), total inorganic nitrogen (TIN) and NO₃-N+NO₂-N. Results revealed that 69% PO₄^3-, 69% NH₃-N, 59% TKN, 60% TN, 64% TON, 67% TIN and 56% NO₃-N+NO₂-N. These removal efficacies were attained for a hydraulic retention time of 18 hours for both SBRs with a solids retention time of 5 days for SBR-1 and 7 days for SBR-2. Findings of this study showed that the cyclic aerobic-anaerobic set-up on a laboratory scale SBR, inoculated with activated sludge for treatment of brewery wastewater for biological nutrients was feasible. It is recommended that investigation on BNR using brewery wastewater with a well-balanced C: N: P ratio should be done to improve BNR efficacies.