Effect of Granular Activated Carbon Addition on Membrane Fouling in a Membrane Bioreactor

With the mitigation of membrane fouling by aeration in the membrane bioreactor (MBR), advanced treatments such as activated carbon, synthetic resin adsorption, and coagulation for reducing a foulants have been studied. Activated carbon adsorption is a common and generally effective treatment method for removing organic compounds with small molecular weight in wastewater treatment plants. Biofiltration of a submerged MBR using a dead-end stirrer cell was conducted to investigate the effects of granular activated carbon (GAC) addition to the MBR on substrate removal and the membrane fouling mitigation. Real wastewater (32±4 NTU, 34±0.7 mgTOC/L, 23±0.2 mgT-N/L, 5±0.08 mgT-P/L, and 4600±30 mgMLSS/L), used as raw water, was collected from a real aeration tank. Compared with the MBR in the absence of GAC, the membrane filtration of MBR with the addition of GAC achieved a higher efficiency (exceeding 92%) for particles and organic matter, except T-N for which it exhibited lower efficiency (<45%) regardless of the permeate flux. An increase in permeate flux resulted in a rise in transmembrane pressure (TMP) and total membrane resistance regardless of the addition of GAC to MBR, indicating that both low permeate flux and high solid retention time for MBRs with and without the addition of GAC are needed to improve membrane resistance and enhance the efficiency of nitrogen removal by providing an oxic and anoxic zone in the GAC in MBR.