Membrane Bioreactor Performance for Treatment of Domestic Wastewater in a Peri-Urban Community in Kwara State

Decentralised wastewater treatment in peri-urban communities of Kwara State, North Central Nigeria, is constrained by limited infrastructure and technical capacity, and membrane bioreactor technology offers a compact, high-performance alternative to conventional activated sludge systems for community-scale applications. This study evaluates the performance of a pilot-scale submerged membrane bioreactor treating domestic wastewater from a residential community in Offa, Kwara State, over a six-month operational period. The pilot system incorporated a flat-sheet ultrafiltration membrane with a nominal pore size of 0.04 microns submerged in an aerated bioreactor. System performance was evaluated for biochemical oxygen demand, chemical oxygen demand, total suspended solids, ammonia-nitrogen, total nitrogen, total phosphorus, and faecal coliforms at hydraulic retention times of 4, 6, and 8 hours. Membrane fouling development was characterised by transmembrane pressure monitoring, and fouling mechanisms were analysed using filtration resistance models. At an 8-hour hydraulic retention time, the system achieved BOD, COD, and TSS removals exceeding 97%, 96%, and 99%, respectively, producing effluent that met NESREA surface water discharge standards. Ammonia-nitrogen removal averaged 93.4%, with full nitrification achieved. Faecal coliform levels in the permeate were undetectable by membrane separation alone. Transmembrane pressure increased from 8.2 kPa to 31.4 kPa over 60 operating days, with cake layer fouling identified as the dominant resistance. Backwash optimisation reduced fouling rate by 34%. The study demonstrates membrane bioreactor viability for peri-urban wastewater treatment in North Central Nigeria. Keywords: membrane bioreactor, domestic wastewater, fouling, Kwara State, peri-urban treatment