The performance of a biological aerated filter (BAF) system was studied to assess the effects of different aeration rates on simultaneous ammonium (NH4+-N) and manganese (Mn2+) removal from drinking water. Samples of drinking water with simulated high and low strengths of pollution with chemical oxygen demand (COD), NH4+-N and Mn2+ were used to evaluate the bio-filtration system. For high-strength polluted drinking water, the BAF system showed insignificant COD removal with increased aeration rate (AR). An AR of 2.0 L/min (dissolved oxygen: 5.26 mg/L) led to higher (99.3%) removal of NH4+-N and an effluent concentration below the regulated concentration limit (<1.5 mg/L). However, higher manganese removal (99.1%) was achieved at an AR of 0.3 L/min (dissolved oxygen: 2.94 mg/L). Furthermore, for low-strength polluted drinking water, up to 98.4% of NH4+-N and 82.9% of Mn2+ were removed simultaneously at an AR of 0.1 L/min (DO: 4.68 mg/L). The best conditions for simultaneous NH4+-N and Mn2+ removal from high-strength polluted drinking water were achieved at ARs of 2.0 L/min and 0.3 L/min, respectively, while their removal from low-strength polluted drinking water was optimised with an AR of 0.1 L/min. (C) 2013 Elsevier B.V. All rights reserved.