Browsing by Author "Ge, Zheng"
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- Energy-efficient Wastewater Treatment by Microbial Fuel Cells: Scaling Up and OptimizationGe, Zheng (Virginia Tech, 2015-11-06)Microbial fuel cells (MFCs) are potentially advantageous as an energy-efficient approach to wastewater treatment. For single-chamber tubular MFCs, anode effluent is used as catholyte instead of tap water or buffer solutions. Therefore, exposing cathode electrode to atmosphere could be also considered as a passive aeration for further aerobic oxidation of organics and nitrification. Based on several bench-scale studies, a 200-L scale MFC system with passive aeration process has been developed for treating actual municipal wastewater after primary clarification. The integrated system was able to remove over 80% organic contaminants and solid content from primary effluent. Through parallel and serial electricity connection, the power output of ~200 mW and the conversion efficiency of ~80% for charging capacitors were achieved by using commercially available energy harvesting device (BQ 25504). The treatment system is energy-efficient for the energy saving from aeration and sludge treatment while partial energy recovery as direct electricity can be utilized on site to power small electric devices. However, the post treatments are required to polish the effluent for nutrients removal.
- Long-term performance of a 200 liter modularized microbial fuel cell system treating municipal wastewater: treatment, energy, and costGe, Zheng; He, Zhen (Royal Society of Chemistry, 2016-02-04)Microbial fuel cells (MFCs) have been intensively studied at a bench scale and the further development of this technology requires system scaling up and understanding of their performance under non-laboratory conditions. In this study, a 200 L modularized MFC system consisting of 96 MFC modules was developed and operated in a local wastewater treatment plant for treating primary effluent. During more than 300 days' operation, the MFC system removed more than 75% of the total chemical oxygen demand and 90% of the suspended solids, despite significant fluctuations in treatment performance affected by wastewater quality and operational factors. It achieved 68% removal of ammonia nitrogen, but phosphorous and the nitrate accumulated due to nitrification needs further disposal. The frequency of the catholyte recirculation exerted a strong effect on the energy consumption of the MFC system. Through both parallel and serial electric connections, the MFC system generated power of ∼200 mW that was extracted by a power management system to drive a 60 W DC pump for catholyte recirculation. Over 60% of the material cost of the MFCs was due to the cation exchange membrane, and the capital cost of the MFC system could be comparable to that of small wastewater treatment facilities. The results of this study encourage the further development of MFC technology with reduced costs and improved performance towards sustainable wastewater treatment.
- Sediment microbial fuel cells for wastewater treatment: challenges and opportunitiesXu, Bojun; Ge, Zheng; He, Zhen (The Royal Society of Chemistry, 2015-03-27)Sediment microbial fuel cells (SMFCs) have been intensively investigated for the harvest of energy from natural sediment, but studies of their application for wastewater treatment mainly occurred in the past 2-3 years. SMFCs with simple structures can generate electrical energy while decontaminating wastewater. Most SMFCs used for wastewater treatment contain plants to mimic constructed wetlands. Both synthetic and real wastewaters have been used as substrates in SMFCs that achieved satisfactory performance in organic removal. SMFCs have also been scaled up from several litres to more than 150 L. To further develop this technology, identification of a suitable application niche is needed. Several challenges must be addressed, including more detailed analysis in energy production, consumption, and application, understanding the relationship between electricity generation and contaminant removal, selecting plants that will benefit electrode reactions, improving nutrients removal, and optimizing system configuration and operation. The potential applications of SMFCs for wastewater treatment include powering sensors to monitor treatment processes and enhancing the removal of specific contaminants by electricity generation.