Department of Urban and Environmental Engineering, Graduate School of Engineering, Hokkaido University, North-13, West-8, Kita-ku, Sapporo 060-8628, Japan.
Bioresour Technol. 2011 Jan;102(1):355-60. doi: 10.1016/j.biortech.2010.04.091. Epub 2010 May 23.
A two-chamber MFC system was operated continuously for more than 500 days to evaluate effects of biofilm and chemical scale formation on the cathode electrode on power generation. A stable power density of 0.57 W/m(2) was attained after 200 days operation. However, the power density decreased drastically to 0.2 W/m(2) after the cathodic biofilm and chemical scale were removed. As the cathodic biofilm and chemical scale partially accumulated on the cathode, the power density gradually recovered with time. Microbial community structure of the cathodic biofilm was analyzed based on 16S rRNA clone libraries. The clones closely related to Xanthomonadaceae bacterium and Xanthomonas sp. in the Gammaproteobacteria subdivision were most frequently retrieved from the cathodic biofilm. Results of the SEM-EDX analysis revealed that the cation species (Na(+) and Ca(2+)) were main constituents of chemical scale, indicating that these cations diffused from the anode chamber through the Nafion membrane. However, an excess accumulation of the biofilm and chemical scale on the cathode exhibited adverse effects on the power generation due to a decrease in the active cathode surface area and an increase in diffusion resistance for oxygen. Thus, it is important to properly control the formation of chemical scale and biofilm on the cathode during long-term operation.
采用双室 MFC 系统连续运行超过 500 天，以评估生物膜和化学垢形成对阴极电极发电性能的影响。经过 200 天的运行，获得了 0.57 W/m(2)的稳定功率密度。然而，当去除阴极生物膜和化学垢后，功率密度急剧下降至 0.2 W/m(2)。随着阴极生物膜和化学垢部分在阴极上累积，功率密度随时间逐渐恢复。根据 16S rRNA 克隆文库分析了阴极生物膜的微生物群落结构。从阴极生物膜中最常检索到与黄单胞菌科细菌和 Gammaproteobacteria 亚群中的黄单胞菌密切相关的克隆。SEM-EDX 分析结果表明，阳离子（Na(+)和 Ca(2+)）是化学垢的主要成分，表明这些阳离子通过 Nafion 膜从阳极室扩散而来。然而，由于阴极活性表面积减少和氧气扩散阻力增加，生物膜和化学垢在阴极上的过度积累对发电产生了不利影响。因此，在长期运行过程中，适当控制阴极上化学垢和生物膜的形成非常重要。
