Wastewater treatment with combined upflow anaerobic fixed-bed and suspended aerobic reactor equipped with a membrane unit

A combined upflow anaerobic fixed-bed (UAF-B), using pumice as a biofilter material, and a suspended aerobic activated sludge bioreactor (SAR) equipped with a microfiltration (MF) unit has been designed. This system exhibited high performance on the removal of organic matter. COD removal efficiencies were in the range of 94–98.7% with organic loading rates (OLR) of 3.67–16.56 kg COD m −3 per day. Phosphorous and nitrogenous materials were removed from the wastewater as well as COD. High PO 4-P removal efficiencies (96–97%) were achieved in this study. NO 2-N and NO 3-N concentrations in the effluent of MF were less than 1.0 mg l −1 through most experiments. Suspended solid concentrations measured in the effluent were below the detectable levels. Biofilm development and microbial communities were investigated using scanning electron microscopy (SEM).