Impact of micro-aerobic conditions in UASB Reactor using media to improve the removal efficiency of organics and nutrients from wastewater

The present study attempted to investigate the impact of the micro-aerobic condition in a conventional Up-Flow Anaerobic Sludge Blanket Reactor (UASB) using different media for the treatment of municipal wastewater. The Hydraulic Retention Time (HRT), Dissolved Oxygen (DO), intermittent and continuous aeration were the important operating conditions of this study carried out for more than 1015 days. Fourier transform infra red (FTIR) spectra and SEM analysis indicate the significant growth of the microbiota responsible for the removal of nutrients. Significant increase in the removal of the chemical oxygen demand (COD)∼ 91%, biochemical oxygen demand (BOD)∼ 90%, suspended solids (SS)∼ 92%, and ammonical nitrogen (NH₄⁺–N)∼ 90%, were observed at lower DO levels. Sulphate was dominant due to sulphide oxidation during micro-aerobic conditions in almost all study phases, which resulted in an increase of up to 90% of the influent sulphates. The micro-aerobic UASB process could be a feasible option for achieving the latest treated effluent disposal norms and significantly reducing the energy demand for wastewater treatment.