Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China.
Sci Total Environ. 2022 Jul 20;831:154798. doi: 10.1016/j.scitotenv.2022.154798. Epub 2022 Apr 1.
The aim of this study was to establish the relationship between spatial distribution of Geobacter and electric intensity in the microbial electrolysis desalination and chemical-production cell (MEDCC) and to investigate the effect of enlarged volumetric anode on the performance of MEDCC. The MEDCC was constructed with nine carbon brush anodes (length × diameter = 11 cm × 3 cm) as enlarged volumetric anode, and operated by feeding with 1 g/L acetate as substrate and 35 g/L NaCl as artificial seawater under the applied voltages of 1.2-4.5 V. Spatial distribution of Geobacter in the anodic biofilm was determined according to the bacterial community analysis on 27 biofilm samples from the top, middle and bottom layers of anodes (i.e., with distance of 4.5, 10, and 15.5 cm to the cathode, respectively). Results showed that the enlarged volumetric anode significantly improved the performance of MEDCC. The maximum desalination rate and current density reached 338.5 ± 21.8 mg/L∙h and 55.7 ± 3.7 A/m in the MEDCC, respectively. The electric intensity values decreased with the distance from the anode to the cathode and formed an uneven distribution in the anode chamber. The samples in the top layer of anodes had the highest average 16S rRNA gene copy number of Geobacter of 1.55 × 10 copies/μL, which was 18 times higher than that in the bottom layer of anodes. A linear relation was established between the spatial distribution of Geobacter and electric intensity (R = 0.994-0.999). The electric intensity gradient created the uneven spatial distribution of Geobacter in the biofilms of volumetric anode. Results from this study could be useful to enrich Geobacter in the anodic biofilm thus to improve the performance of MEDCC.
本研究旨在建立微生物电解淡化和化学产电池（MEDCC）中 Geobacter 的空间分布与电场强度之间的关系，并研究扩大体积阳极对 MEDCC 性能的影响。MEDCC 采用 9 根碳刷阳极（长×直径=11 cm×3 cm）作为扩大体积阳极构建，以 1 g/L 乙酸盐为底物和 35 g/L 氯化钠为人工海水运行，在 1.2-4.5 V 的应用电压下运行。根据阳极生物膜上 27 个生物膜样本的细菌群落分析（即距阴极分别为 4.5、10 和 15.5 cm），确定阳极生物膜中 Geobacter 的空间分布。结果表明，扩大体积阳极显著提高了 MEDCC 的性能。最大脱盐率和电流密度分别达到 338.5±21.8 mg/L·h 和 55.7±3.7 A/m。电场强度值随距离阳极向阴极而降低，并在阳极室内形成不均匀分布。阳极顶部样本的 Geobacter 16S rRNA 基因拷贝数平均值最高，为 1.55×10 拷贝/μL，是阳极底部样本的 18 倍。Geobacter 的空间分布与电场强度之间建立了线性关系（R=0.994-0.999）。电场强度梯度导致体积阳极生物膜中 Geobacter 的不均匀空间分布。本研究结果可有助于在阳极生物膜中富集 Geobacter，从而提高 MEDCC 的性能。
