School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
School of Metallurgy and Environment, Central South University, Changsha 410083, China.
Water Res. 2023 Mar 1;231:119655. doi: 10.1016/j.watres.2023.119655. Epub 2023 Jan 23.
Although Castellaniella species are crucial for denitrification, there is no report on their capacity to carry out denitrification and anode respiration simultaneously in a bioelectrochemical system (BES). Herein, the ability of a mixed inoculum of electricigenic Castellaniella species to perform simultaneous denitrification and anode respiration coupled with cathodic metals recovery was investigated in a BES. Results showed that 500 mg/L NO-N significantly decreased power generation, whereas 100 and 250 mg/L NO-N had a lesser impact. The single-chamber MFCs (SCMFCs) fed with 100 and 250 mg/L NO-N concentrations achieved a removal efficiency higher than 90% in all cycles. In contrast, the removal efficiency in the SCMFCs declined dramatically at 500 mg/L NO-N, which might be attributable to decreased microbial viability as revealed by SEM and CLSM. EPS protein content and enzymatic activities of the biofilms decreased significantly at this concentration. Cyclic voltammetry results revealed that the 500 mg/L NO-N concentration decreased the redox activities of anodic biofilms, while electrochemical impedance spectroscopy showed that the internal resistance of the SCMFCs at this concentration increased significantly. In addition, BES inoculated with the Castellaniella species was able to simultaneously perform heterotrophic anodic denitrification and cathodic metals recovery from real wastewater. The BES attained Cu, Hg, Pb, and Zn removal efficiencies of 99.86 ± 0.10%, 99.98 ± 0.014%, 99.98 ± 0.01%, and 99.17 ± 0.30%, respectively, from the real wastewater. Cu was bio-electrochemically reduced to Cu and CuO, whereas Hg and HgO constituted the Hg species recovered via bioelectrochemical reduction and chemical deposition, respectively. Furthermore, Pb and Zn were bio-electrochemically reduced to Pb and Zn, respectively. Over 89% of NO-N was removed from the BES anolyte during the recovery of the metals. This research reveals promising denitrifying exoelectrogens for enhanced power generation, NO-N removal, and heavy metals recovery in BES.
虽然 Castellaniella 物种对反硝化至关重要，但目前尚无关于它们在生物电化学系统 (BES) 中同时进行反硝化和阳极呼吸的能力的报告。在此，研究了电生成 Castellaniella 物种的混合接种物在 BES 中同时进行反硝化和阳极呼吸以及阴极金属回收的能力。结果表明，500mg/L 的 NO-N 显著降低了发电能力，而 100 和 250mg/L 的 NO-N 的影响较小。在所有循环中，进料浓度为 100 和 250mg/L 的单室 MFC (SCMFC) 的去除效率均高于 90%。相比之下，进料浓度为 500mg/L 的 SCMFC 的去除效率急剧下降，这可能归因于 SEM 和 CLSM 显示的微生物活力下降。在该浓度下，生物膜的 EPS 蛋白含量和酶活性显著降低。循环伏安法结果表明，500mg/L 的 NO-N 浓度降低了阳极生物膜的氧化还原活性，而电化学阻抗谱表明，该浓度下 SCMFC 的内阻显著增加。此外，用 Castellaniella 物种接种的 BES 能够同时从实际废水中进行异养阳极反硝化和阴极金属回收。BES 从实际废水中分别获得了 99.86±0.10%、99.98±0.014%、99.98±0.01%和 99.17±0.30%的 Cu、Hg、Pb 和 Zn 去除效率。Cu 通过生物电化学还原形成 Cu 和 CuO，Hg 通过生物电化学还原和化学沉积形成 Hg 物种，HgO 构成 Hg 物种。此外，Pb 和 Zn 分别通过生物电化学还原形成 Pb 和 Zn。在回收金属的过程中，BES 阳极液中超过 89%的 NO-N 被去除。这项研究为 BES 中增强发电、去除 NO-N 和回收重金属的反硝化外生菌提供了有希望的选择。
