School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China.
School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Wuxi 214122, China; Jiangsu Collaborative Innovation Center of Water Treatment Technology and Material, Suzhou 215011, China.
Sci Total Environ. 2021 Jul 10;777:145752. doi: 10.1016/j.scitotenv.2021.145752. Epub 2021 Mar 2.
The anaerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) in high salinity wastewater is rather hard due to the inhibition of microorganisms by complex and high dosage of salts. Microbial electrolysis cell (MEC), with its excellent characteristic of anodic biofilms, can be an effective way to enhance the PAHs biodegradation. This work evaluated the impact of NaCl concentrations (0 g/L, 10 g/L, 30 g/L, and 60 g/L) on naphthalene biodegradation and analyzed the damage protection mechanism of anodic biofilms in batching MECs. Compared with the open circuit, the degradation efficiency of naphthalene under the closed circuit with 10 g/L NaCl concentration reached the maximum of 95.17% within 5 days. Even when NaCl concentration reached 60 g/L, the degradation efficiency only decreased by 10.02%, compared with the MEC without additional NaCl. Confocal scanning laser microscope (CSLM) proved the superiority of the biofilm states of MEC anode under high salinity in terms of thicker biofilms and higher proportion of live/dead bacteria cells. The highest dehydrogenase activity (DHA) was found in the MEC with 10 g/L NaCl concentration. Moreover, microbial diversity analysis demonstrated the classical electroactive microorganisms Geobacter and Pseudomonas were found on the anodic biofilms of MECs, which have both PAHs degradability and the electrochemical activity. Therefore, this study proved that high salinity had adverse effects on the anodic biofilms, but MEC alleviated the damage caused by high salinity.
高盐废水中多环芳烃（PAHs）的厌氧生物降解由于盐的复杂性和高剂量对微生物的抑制作用而相当困难。微生物电解池（MEC）具有阳极生物膜的优良特性，是增强 PAHs 生物降解的有效方法。本工作评估了 NaCl 浓度（0 g/L、10 g/L、30 g/L 和 60 g/L）对萘生物降解的影响，并分析了分批式 MEC 中阳极生物膜的损伤保护机制。与开路相比，在 10 g/L NaCl 浓度的闭路中，萘的降解效率在 5 天内达到 95.17%的最大值。即使 NaCl 浓度达到 60 g/L，与不添加额外 NaCl 的 MEC 相比，降解效率仅降低了 10.02%。共聚焦扫描激光显微镜（CSLM）证明了高盐条件下 MEC 阳极生物膜状态的优越性，表现在生物膜更厚，活/死细菌细胞的比例更高。在 10 g/L NaCl 浓度的 MEC 中发现了最高的脱氢酶活性（DHA）。此外，微生物多样性分析表明，具有 PAHs 降解能力和电化学活性的经典电活性微生物 Geobacter 和 Pseudomonas 存在于 MEC 的阳极生物膜上。因此，本研究证明高盐度对阳极生物膜有不利影响，但 MEC 减轻了高盐度造成的损害。
