Anaerobic Baffled Reactor Combined With Membrane Bioreactor For Treating Oilfield Wastewater Containing HPAM

Petroleum is an important and non-renewable fossil fuel related to the lifeblood of economic development. Therefore, in order to enhance oil recovery in the drilling process, polymer flooding as one of the most effective technique of tertiary oil recovery has been widely used. However, plenty of wastewater containing polyacrylamide (HPAM) were produced at the same time. This kind of wastewater has high viscosity, high mineral content and is difficult to be biodegraded. Meanwhile, acrylamide monomer has high neurotoxic and carcinogenic. With the accumulation of un-degraded HPAM in the environment, human health threats and environmental pollution may be generated. Thus, the treatment of this kind of wastewater has become one of the important issues which must be solved.The contents of this thesis include research on treatment of oil field wastewater containing HPAM. using the simulated wastewater containing HPAM prepared according to produced water from the Southern Forth Area in Da Qing oilfield, by the combined Anaerobic Baffled Reactor (ABR) and Membrane Bioreactor (MBR), the start-up and the removal efficiency during operation were studied. The main results and the conclusions are as follows:(1) After ABR and MBR reactor inoculated with sludge, it took about eighty-four days to start successfully. By using gradient change method to adjust the feed water, At the end of start-up phase, the removal rate of COD was more than89%, the removal rate of HPAM was above90%, the simulated polymer-bearing wastewater were successfully treated. According to the phenomena observed on the membrane surface, most of the HPAM in wastewater may be intercepted by membrane in MBR, which may have a great effect on membrane fouling.(2) During the start-up and operation of the combined ABR with MBR, the removal rate of COD and HPAM in ABR were very low. Therefore, using carbon fiber felt as anode electrode, Sediment Microbial Fuel Cell (SMFC) was formed in each ABR chamber. After about forty days" operation, electricity/power is generated and the removal rate of COD and HPAM in ABR are successfully improved.(3) HPAM in wastewater were found intercepted by membrane in MBR, and the serious membrane fouling was observed. By applying a low voltage and low intensity electric field in MBR, the membrane fouling contributed by HPAM were significantly reduced and the membrane flux is also improved.(4) Chemical Fenton and electrochemical Fenton oxidation/degradation of HPAM were studied and compared. By using chemical-Fenton and electro-Fenton system separately for the degradation of HPAM, the result of the degradation of HPAM was measured. Under the optimal conditions, the removal rate on100mg/L HPAM in chemical-Fenton system was80%, and the removal rate in electro-Fenton was55%.