Department of Civil & Environmental Engineering, University of Missouri, Columbia, MO, 65211, USA.
HDR, Inc., Kansas City, MO, 64131, USA.
Environ Sci Pollut Res Int. 2019 Nov;26(31):31945-31955. doi: 10.1007/s11356-019-06289-2. Epub 2019 Sep 6.
Bioelectrochemical systems (BESs) including microbial electrolysis cells (MECs) and microbial fuel cells (MFCs) are promising for hexavalent chromium [Cr(VI)] reduction and total chromium (Cr) removal from wastewater. This study assessed the performance of simple, inexpensive, and continuous flow BESs with neither cathode catalyst nor proton exchange membrane for Cr(VI) reduction and total Cr removal. The effect of bioreactor configuration and wastewater feed mode on the performance of the BESs was investigated. Biological Cr(VI) reduction in the MEC followed a first-order kinetics with a rate constant of 0.103 d, significantly higher than that of the control (0.033 d). For comparison, the first-order reduction rate constants in the MFCs with the Cr(VI) fed to the anodic and the cathodic zones were 0.072 and 0.064 d, respectively. The BESs improved total Cr removal through coprecipitating Cr(III) and phosphors as evidenced from the scanning electron microscopy energy-dispersive X-ray spectroscopy analysis. The total Cr removal efficiencies in the control, MFCs, and MEC were 26.1%, 56.7%, and 66.2%, respectively. Only 25.1% to 26.7% of total Cr was present intracellularly in the BESs (both MFCs and MEC), whereas 31.8% ± 1.4% and 38.0% ± 0.9% of total Cr in the anodic and cathodic zones of the control were present intracellularly. Overall, the BESs demonstrated a great potential to reduce Cr(VI) and remove total Cr with the MEC having the fastest Cr(VI) reduction and most efficient total Cr removal. Furthermore, the BESs significantly reduced the intracellular total Cr content.
生物电化学系统（BESs）包括微生物电解池（MECs）和微生物燃料电池（MFCs），有望用于还原六价铬[Cr（VI）]并从废水中去除总铬（Cr）。本研究评估了简单、廉价且连续流动的 BES 用于 Cr（VI）还原和总 Cr 去除的性能，这些 BES 既没有阴极催化剂也没有质子交换膜。研究了生物反应器构型和废水进料方式对 BES 性能的影响。MEC 中的生物 Cr（VI）还原遵循一级动力学，速率常数为 0.103 d，明显高于对照（0.033 d）。相比之下，Cr（VI）分别进料到阳极区和阴极区的 MFC 的一级还原速率常数分别为 0.072 和 0.064 d。BES 通过共沉淀 Cr（III）和磷来提高总 Cr 去除率，这可以从扫描电子显微镜能谱分析中得到证明。对照、MFC 和 MEC 的总 Cr 去除效率分别为 26.1%、56.7%和 66.2%。BES 中（MFC 和 MEC）总 Cr 的细胞内含量仅为 25.1%至 26.7%，而对照中阳极区和阴极区的总 Cr 的细胞内含量分别为 31.8%±1.4%和 38.0%±0.9%。总的来说，BES 具有很大的潜力来还原 Cr（VI）和去除总 Cr，其中 MEC 具有最快的 Cr（VI）还原和最高效的总 Cr 去除。此外，BES 显著降低了细胞内总 Cr 含量。
