Conventional oil sewage treatment methods can achieve satisfactory removal efficiency, but energy consumption problems during the process of oil sewage treatment are worth attention. The integration of a constructed wetland reactor and a microbial fuel cell reactor (CW-MFC) to treat oil-contaminated wastewater, compared with a microbial fuel cell reactor (MFC) alone and a constructed wetland reactor (CW) alone, was explored in this research. Performances of the three reactors including chemical oxygen demand (COD), oil removal, and output voltage generation were continuously monitored. The COD removals of three reactors were between 73% and 75%, and oil removals were over 95.7%. Compared with MFC, the CW-MFC with a MnO2 modified cathode produced higher power density and output voltage. Maximum power densities of CW-MFC and MFC were 3868 mW/m3 (102 mW/m2) and 3044 mW/m3 (80 mW/m2), respectively. The plants in CW-MFC play a positive role for reactor cathode potential. Both plants and cathode modification can improve reactor performance of electricity generation.

Abstract:The anode electrode is one of the most important components in all microbial electrochemical technologies (METs). Anode materials pretreatment and modification have been shown to be an effective method of improving anode performance. According to mass loss analysis during carbon fiber heating, five temperatures (300, 450, 500, 600, and 750 • C) were selected as the pre-heating temperatures of carbon fiber brush anodes. Microbial fuel cell (MFC) reactors built up with these pre-heated carbon brush anodes performed with different power densities and Coulombic efficiencies (CEs). Two kinds of measuring methods for power density were applied, and the numerical values of maximum power densities diverged greatly. Reactors with 450 • C anodes, using both methods, had the highest power densities, and the highest CEs were found using 500 • C anode reactors. The surface elements of heat-treated carbon fibers were analyzed using X-ray photoelectron spectra (XPS), and C, O, and N were the main constituents of the carbon fiber. There were four forms of N1s at the surface of the polyacrylonitrile (PAN)-based carbon fiber, and their concentrations were different at different temperature samples. The microbial community of the anode surface was analyzed, and microbial species on anodes from every sample were similar. The differences in anode performance may be caused by mass loss and by the surface elements. For carbon brush anodes used in MFCs or other BESs, 450-500 • C preheating was the most suitable temperature range in terms of the power densities and CEs.

No abstract

Constructed wetland (CW) is a low cost and easy operation process for wastewater treatment, while filler clogging is one of the disadvantages for this technology. Using activated carbon as the filler, a regular CW and an integration of constructed wetland with microbial fuel cell (CW-MFC) were constructed. After continuous operation of four months, specific surface area and pore size distribution of the activated carbon were analyzed. The specific surface area of the fresh activated carbon was 133.8 m2/g, while the filler in the CW and CW-MFC systems had specific surface area of 38.1 m2/g and 58.2 m2/g. The surface decrease of the CW-MFC filler was 21% lower than that of CW filler. Comparing with the regular CW, the filler in the CW-MFC was more clogging resistant. The alleviation of the filler clogging in CW-MFC may be caused by the micro-electric field as the function of MFC. CW-MFC is a promising microbial electrochemical technology for wastewater treatment and filler clogging resistant, there are some detailed issues deserve to be further researched.

No abstract