Liu Xueyu, Zhu Hongguang
Biomass Energy Research Center, Tongji University, Shanghai 201804, P. R. China.
ACS Omega. 2020 Oct 21;5(43):27823-27832. doi: 10.1021/acsomega.0c02828. eCollection 2020 Nov 3.
The traditional biological denitrification process has the problems of low removal rates and lack of a carbon source when treating wastewater with high ammonia nitrogen concentration and a low carbon-nitrogen ratio. Based on a bio-electrochemical system (BES), a novel carbon cloth bipolar plate multicompartment electroenhanced bioreactor (CBM-EEB) system was constructed. In this study, nitrogen removal efficiency and enrichment of functional bacteria using CBM-EEB under different voltage conditions were investigated. The results from next-generation sequencing indicated that the CBM-EEB included heterotrophic nitrification and aerobic denitrification (HNAD) and was dominated by heterotrophic nitrification aerobic denitrifying bacteria (HNADB). The applied voltage was confirmed as having the ability to regulate the microbial community structure and abundance of functional genes, thereby further enhancing the nitrogen removal efficiency of the system. The total nitrogen removal efficiency was 77.70 ± 1.14, 87.10 ± 0.56, 86.40 ± 0.59, and 89.30 ± 0.53% under applied voltages of 0.4, 0.7, 1.0, and 1.3 V, respectively. All values were significantly higher than the control group (62.86 ± 2.06%). HNADB had the highest abundance among the 17 detected genera related to nitrogen metabolism. Facultative denitrifying bacteria, Pseudoxanthomonas, along with key bacteria of HNADB, such as Flavobacterium, constructed a shortcut simultaneous nitrification-denitrification (SND) process. Poisson analysis and redundancy analysis (RDA) showed that the applied voltage improved the denitrification efficiency by changing the microbial community structure, reducing the abundance of heterotrophic bacteria, and increasing the unit abundance of key functional genes so that less organics were required for the denitrification process. The increased nitrogen removal efficiency in the experimental group was mainly related to simultaneous nitrification-denitrification process and cooperation of microbial communities in the anode and the cathode. This study highlighted the feasibility of CBM-EEB to enhance the HNAD reaction and the response of wastewater with a low C/N ratio to enhance the abundance of microbial bacteria and their functional gene abundance.
传统生物脱氮工艺在处理高氨氮浓度、低碳氮比废水时存在去除率低和碳源不足的问题。基于生物电化学系统（BES），构建了一种新型的碳布双极板多室电增强生物反应器（CBM-EEB）系统。本研究考察了不同电压条件下CBM-EEB对氮的去除效率及功能菌的富集情况。二代测序结果表明，CBM-EEB中存在异养硝化和好氧反硝化（HNAD）作用，且以异养硝化好氧反硝化细菌（HNADB）为主。证实施加电压能够调节微生物群落结构和功能基因丰度，从而进一步提高系统的脱氮效率。在0.4、0.7、1.0和1.3 V的施加电压下，总氮去除效率分别为77.70±1.14%、87.10±0.56%、86.40±0.59%和89.30±0.53%。所有数值均显著高于对照组（62.86±2.06%）。在17个检测到的与氮代谢相关的属中，HNADB的丰度最高。兼性反硝化细菌假黄单胞菌与HNADB的关键细菌（如黄杆菌）共同构建了一条短程同步硝化反硝化（SND）途径。泊松分析和冗余分析（RDA）表明，施加电压通过改变微生物群落结构、降低异养细菌丰度和增加关键功能基因的单位丰度来提高反硝化效率，从而使反硝化过程所需的有机物减少。实验组脱氮效率的提高主要与同步硝化反硝化过程以及阳极和阴极微生物群落的协同作用有关。本研究突出了CBM-EEB强化HNAD反应的可行性以及对低碳氮比废水的响应，以提高微生物细菌及其功能基因丰度。
