Research Of Producing Electricity Characteristics Of Microbial Fuel Cell And The Application Of Wastewater Treatment Of Oilfield Wastewater

MFCs are devices which use bacteria as the biocatalyst to oxidize organic matter and generate electricity. MFC can treat wastewater and generate electricity simultaneously. This is very important for sustainable development. Oilfield wastewaters contain a large number of refractory organics such as petroleum, polymer and surfactant. The three major oilfield wastewaters are including water flooding produced water, polymer flooding produced water and ASP flooding produced water. These three kinds of wastewaters are the first time used as anode substrate of three MFCs in this study. The influence and the influencing factors of the output voltage of the three MFCs and the produced water main refractory organics removal effect were studied. PBS, temperature and the cathode type are important factors that affect MFC’s performance, so it is necessary to have a deep research on them. Traditional double chamber microbial fuel cells were used in this paper. The anode and cathode were made of graphite fiber brush. Titanium wire was used to connect the circuit (500Ω resistor except when stated otherwise). The anode sludge came from the sewage treatment plant.0.1g/L glucose was used as the substrate during set-up. After the reactors were stable, oilfield wastewater was the only substrate of the system.In order to study the effects of the PBS on the three kinds of oilfield produced water as anode substrate on MFC, the experiment was conducted under the condition that20℃and K3Fe(CN)6as catholyte,6groups of MFC anode substrate in PBS and raw water had been set up respectively. In a same condition, the maximum voltages at water flooding raw water, water flooding produced water with PBS, polymer flooding raw water, polymer flooding produced water with PBS, ASP flooding raw water and ASP flooding produced water with PBS were426mV,458mV,586mV,631mV,625mV and723mV respectively. And the anode potential were-152mV,-182mV,-309mV,-352mV,-348mV and-446mV respectively. During a running cycle reaction, six groups of microbial fuel cell cathode potential changed little, kept maintain at267-276mV. The pH of water flooding raw water, polymer flooding raw water and asp flooding raw water decreased1.28,1.73and1.77, respectively. Results showed that the anode contributes mostly to the change in output voltage. Without PBS can effectively reduce the pH in reaction process of produced water.The other conditions remain unchanged, choose asp flooding raw water as anode substrate The maximum voltages at35℃,30℃,20℃and15℃were808mV,744mV,625mV and339mV. And the maximum output power were3.715mW,1.989mW,0.804mW and0.232mW respectively. Internal resistances were71Ω,128Ω,320Q and735Ω.. Coulombic efficiencies (CE) were31.23%,29.79%,25.48%and19.55%. COD removal rates were 34.46%,33.03%,32.01%and10.11%at35℃,30℃,20℃and15℃respectively. The results show that temperature had a significant impact on output power, internal resistance, CE and COD.Run the biological cathode under the condition of35℃and ASP flooding raw water with MFC. Dissolved oxygen gradient experiments show the optimum dissolved oxygen (DO) in catholyte was between3-4mg/L, along with the highest output power and CE. Under the same condition, the maximum voltages at biological cathode MFC with3mg/L DO and K3Fe(CN)6cathode MFC were925mV and808mV respectively. And the maximum output power were5.74mW,3.715mW respectively. Coulombic efficiencies were23.23%,20.23%. COD removal rates were34.46%,34.07%.It means that temperature decreasing had evident effect on output voltages, output power and CE. The main pollutant removal efficiency of produced water is equivalent between regular aerobic biological treatment and biological cathode MFC. But biological cathode can effectively control the pH increases in the aerobic biological treatment.The electricity generation performance and water quality purification efficiency of ASP flooding produced water MFC are the best among the three kinds of produced water. The main pollutant removal efficiency of the ASP flooding produced water is:petroleum material<polymer<surfactant.