Organic matter recovery from municipal wastewater by using dynamic membrane separation process

Abstract

An upflow dynamic membrane separation (DMS) process was developed for organic matter recovery from low-strength municipal wastewater. During the operation of 300days, 81.6% of organic matter recovery rate on average was achieved at a high membrane flux of 60L/(m2h). Chemical analyses and batch assays revealed that the recovered organic matter (ROM) had larger carbon to nitrogen mass ratio (C/N) and higher fermentation potential compared to the waste activated sludge. The transformation of the organic matter occurred in the DMS process, which was related to the polyferric sulfate (PFS) coagulation, anaerobic metabolism and membrane retention. The recovery of soluble organic matter was facilitated by the coagulation, and the transformation was observed in the sludge zone due to the anaerobic metabolism. Although the dynamic membrane was less efficient to remove the small molecules, it allowed a sound retention of particulate fractions and biopolymers, enabling a relatively high ROM recovery in the DMS process. Furthermore, the net operation expenditure for the novel wastewater treatment paradigm employing the DMS process was about 0.24kWh/m3, much lower than that (1.10kWh/m3) for the conventional membrane bioreactor treatment technology. These results indicated that the upflow DMS process was a promising approach for sustainable wastewater treatment.