Biological Nutrient Removal from On-Site Wastewater Treatment Systems Using a Membrane Aerated Bioreactor

This study aimed to develop a low cost bioreactor process to efficiently remove organic compounds and nutrients from on-site wastewater treatment systems. A laboratory-scale anaerobic membrane-aerated biofilm bioreactor (ANMABR) using a gas-permeable silicone tubing covered with non-woven fabrics was constructed to evaluate the efficiency of chemical oxygen demand (COD) and nitrogen removal in the system. After 250 days of continuous reactor operation, the experiment results showed consistent COD and NH₄—N removal efficiencies at 89±6 and 82±5%, respectively. The total nitrogen (TN) removal efficiency was 64±8% with an effluent average total nitrogen concentration of 11 mg/L. From day 89 to day 120 the biofilm reactor experienced a shock load running with C/N ratio of 2:1 with influent NH₄—N increased to 150 mg/L. The COD removal efficiency was not affected after the shock load, but NH₄—N and TN removal efficiencies were decreased down to 44 and 22%, respectively. This study demonstrated that gas-permeable tubing/membrane could be used to treat wastewater containing low organic and nitrogen loadings from on-site wastewater treatment systems. Improvement is still needed under the shock loading conditions for on-site wastewater treatment systems.