Performance evaluation and characterization of an innovative membrane bioreactor in the treatment of wastewater and removal of pharmaceuticals and pesticides.

摘要

The Membrane Bioreactor (MBR) process has been widely applied in the water/wastewater treatment field, and is regarded as an important next-generation technology for wastewater treatment plants. Extensive research and industrial practices have been going on for process optimization and cost reduction. In this study, an innovative thick membrane with large pore sizes was used to develop a new gravity flow MBR process. Two MBR reactors with 0.25cm and 0.48cm thick membrane sheets were operated in parallel to a Conventional Activated Sludge (CAS) reactor. Operation conditions were identical for both processes during the treatment of a synthetic wastewater.;The objectives of this study include: (1) Test the long term wastewater treatment performance of this new MBR process and the impact of sludge ages; (2) Study the membrane fouling/plugging propensity during the operation, fouling development mechanism and potential control measures; (3) Evaluate the possible application of this innovative MBR process on the removal of emerging contaminants such as pharmaceutical/pesticide chemicals at low concentration level.;Research results demonstrated that: (1) Consistent permeate water quality was achieved throughout the one year periods under SRT of 6 days and 15 days respectively; (2) The bigger membrane pore size allows this novel MBR system to be operated with less energy and low maintenance requirements, as well as obtaining better effluent quality than CAS system; (3) This MBR system demonstrated reliable long-term anti-fouling ability. Mixed liquor concentration was the major contributing factor for membrane fouling of this MBR system. Dynamic biofilm that formed inside the membrane pores and sludge cake layer on membrane surface improved permeate water quality and strengthened fouling resistance. (4) Removal of selected emerging contaminant chemicals was compound-specific and there was no significant difference between MBR and CAS on percentage of removals.;Findings from this research testified the promising application of the innovative MBR process within certain industrial niches such as small scale de-centralized wastewater treatment, pre-treatment ahead of NF/RO process for water reuse, and so forth. To optimize its practical application, additional studies are suggested on flux increase, system compactness improvement, anti-fouling cleaning strategies, and development of other innovative applications.