Anaerobic/anoxic/oxic configuration in hybrid moving bed biofilm reactor-membrane bioreactor for nutrient removal from municipal wastewater

A membrane bioreactor (MBRp), a hybrid moving bed biofilm reactor-membrane bioreactor containing carriers in the anaerobic, anoxic and aerobic zones (hybrid MBBR-MBRap) and a hybrid moving bed biofilm reactor-membrane bioreactor which contained carriers only in the anaerobic and anoxic compartments (hybrid MBBR-MBRbp) were used in parallel and compared regarding the nutrient and organic matter removal from municipal wastewater. The hydraulic retention time (HRT) was 18 h. A kinetic study for the heterotrophic and autotrophic bacteria, mainly nitrite-oxidizing bacteria (NOB), was carried out and related to the nutrient and organic matter removal. The hybrid MBBR-MBRap performed best regarding chemical oxygen demand (COD) and total phosphorus (TP) removals, with values of 85.82 ± 2.12% and 81.42 ± 3.85%, respectively. This system had a higher phosphorus release under anaerobic conditions and a higher phosphorus uptake under aerobic conditions. The highest TN removal efficiency was obtained for the hybrid MBBR-MBRbp, with a value of 61.39 ± 10.71%.