Simultaneous organics and nutrients removal in side-stream aerobic granular sludge membrane bioreactor (AGMBR)

Membrane fouling mitigation has been variously reported in aerobic granular sludge membrane bioreactor (AGMBR). AGMBR has also achieved, to varying degrees, the removal of organics and nitrogen-based compounds from wastewater. However, scanty information is available in the literature on phosphorus removal in AGMBR. Thus, the present study focused on simultaneous removal of organics and both nutrients (nitrogen and phosphorus) in AGMBR at semi-pilot-scale. Aerobic granules were cultivated in a cylindrical reactor with a working volume of 19 L, diameter of 15 cm, and height-to-diameter (H/D) ratio of 8. The effluent from the granular reactor was discharged into a side-stream membrane module. At steady state, the granule mean size, 5-min sludge volume index (SVI₅), SVI₃₀, and MLSS were 576 μm, 40 mL/g, 37 mL/g, and 9200 mg/L, respectively. Results show that the system achieved 98% chemical oxygen demand (COD) degradation, 96–99% total nitrogen (TN) removal, and ≥95% removal of PO4-P. The outstanding removal of both organics and nutrients in the AGMBR is attributed to the coexistence of aerobic and anaerobic layers within the granule as well as the anaerobic feeding adopted.