Tandukar Madan, Huber Samuel J, Onodera Takashi, Pavlostathis Spyros G
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0512, USA.
Environ Sci Technol. 2009 Nov 1;43(21):8159-65. doi: 10.1021/es9014184.
The biocathode of a microbial fuel cell (MFC) offers a promising potential for the reductive treatment of oxidized pollutants. In this study, we demonstrated biological Cr(VI) reduction in the cathode of a MFC and identified putative Cr(VI) reducing microorganisms. The MFC was continuously monitored for Cr(VI) reduction and power generation. Acetate was provided to the anode compartment as substrate and bicarbonate was added to the cathode compartment as the sole external carbon source. The contribution of biomass decay and abiotic processes on Cr(VI) reduction was minimal, confirming that most of the Cr(VI) reduction was assisted by microbial activity in the cathode, which utilizes electrons and protons generated from the oxidation of acetate in the anode compartment. Relatively fast Cr(VI) reduction was observed at initial Cr(VI) concentrations below 80 mg/L. However, at 80 mg Cr(VI)/L, Cr(VI) reduction was extremely slow. A maximum Cr(VI) reduction rate of 0.46 mg Cr(VI)/g VSS.h was achieved, which resulted in a current and power density of 123.4 mA/m(2) and 55.5 mW/m(2), respectively. The reduced chromium was nondetectable in the supernatant of the catholyte which indicated complete removal of chromium as Cr(OH)(3) precipitate. Analysis of the 16S rRNA gene based clone library revealed that the cathode biomass was largely dominated by phylotypes closely related to Trichococcus pasteurii and Pseudomonas aeruginosa, the putative Cr(VI) reducers.
微生物燃料电池（MFC）的生物阴极在还原处理氧化态污染物方面具有广阔的应用前景。在本研究中，我们展示了MFC阴极中生物还原Cr(VI)的过程，并鉴定了可能的Cr(VI)还原微生物。对MFC进行连续监测，以观察Cr(VI)的还原情况和发电情况。向阳极室提供乙酸盐作为底物，并向阴极室添加碳酸氢盐作为唯一的外部碳源。生物质衰减和非生物过程对Cr(VI)还原的贡献极小，这证实了阴极中的微生物活动对大部分Cr(VI)还原起到了促进作用，这些微生物利用阳极室中乙酸氧化产生的电子和质子。在初始Cr(VI)浓度低于80 mg/L时，观察到相对较快的Cr(VI)还原。然而，当Cr(VI)浓度为80 mg/L时，Cr(VI)还原极其缓慢。实现了最大Cr(VI)还原速率为0.46 mg Cr(VI)/g VSS·h，这分别导致了电流密度和功率密度为123.4 mA/m²和55.5 mW/m²。在阴极电解液的上清液中未检测到还原的铬，这表明铬已完全以Cr(OH)₃沉淀的形式去除。基于16S rRNA基因的克隆文库分析表明，阴极生物量主要由与巴氏丝球菌和铜绿假单胞菌密切相关的系统发育型主导，它们是可能的Cr(VI)还原剂。
