Department of Environmental Science, Chongqing University, Chongqing, 400044, China.
Department of Environmental Science, Chongqing University, Chongqing, 400044, China; College of Resources and Environment, Southwest University, Chongqing, 400715, China.
Chemosphere. 2022 Sep;303(Pt 2):135128. doi: 10.1016/j.chemosphere.2022.135128. Epub 2022 May 27.
Fracturing flowback water (FFW) from the shale gas exploitation resulted in environmental burden. FFW could be treated by a microbial fuel cell (MFC), but the challenge for the precipitation of ultrafine particles due to the supersaturation of sulfide remains to be addressed. Herein, we reported a Dual-anode MFC (DA-MFC), in which the FFW remediation and elemental sulfur recovery could be performed by regulating potential of the electrochemical anode. The removal of COD and sulfate was 70.0 ± 1.2% and 75.5 ± 0.4% in DA-MFCs by controlling potential at -0.1 V (vs. SHE) for 36 h. Meanwhile, the efficiency of copper removal and elemental sulfur recovery was up to 99.9 ± 0.5% and 75.6 ± 1.8%, respectively, which was attributed by the electrochemical oxidation of sulfide to elemental sulfur. Trichococcus, unclassified Prolixibacteraceae and unclassified Cloacimonadales enriched on the bioanodes of DA-MFCs were sensitive to potential regulation and favorable for degrading complex organics. UnclassifiedSynergistaceae, Desulfobacterium, Desulfovibrio, unclassified bacteria and Syner-01 was conducive to sulfate removal. Moreover, the elimination of Azoarcus due to potential regulation suppressed the biological oxidation of sulfide. Thus, organics were efficiently removed through the biological oxidation and sulfate reduction on bioanode, the copper ions were combined with the sulfide from sulfate reduction to precipitate effectively, and then the excessive sulfide in the system was converted into elemental sulfur attached on the electrochemical anode. The results provide new sights on bio-electrochemical technology for treatment of wastewater containing complex organics, heavy metals and sulfates.
页岩气开采产生的压裂返排液（FFW）造成了环境负担。FFW 可以通过微生物燃料电池（MFC）进行处理，但由于硫化物的过饱和度，超细颗粒的沉淀仍然是一个挑战。在此，我们报道了一种双阳极微生物燃料电池（DA-MFC），通过调节电化学阳极的电位，可以实现 FFW 的修复和元素硫的回收。在 DA-MFC 中，通过将电位控制在-0.1 V（相对于 SHE）36 h，COD 和硫酸盐的去除率分别达到 70.0±1.2%和 75.5±0.4%。同时，铜去除和元素硫回收的效率分别高达 99.9±0.5%和 75.6±1.8%，这归因于硫化物的电化学氧化为元素硫。DA-MFC 生物阳极上富集的 Trichococcus、未分类的 Prolixibacteraceae 和未分类的 Cloacimonadales 对电位调节敏感，有利于降解复杂有机物。未分类的 Synergistaceae、脱硫杆菌属、脱硫弧菌属、未分类细菌和 Syner-01 有利于硫酸盐的去除。此外，由于电位调节而消除的 Azoarcus 抑制了硫化物的生物氧化。因此，通过生物阳极上的生物氧化和硫酸盐还原，有机物被有效地去除，铜离子与硫酸盐还原产生的硫化物结合有效地沉淀下来，然后系统中过量的硫化物转化为附着在电化学阳极上的元素硫。该结果为处理含有复杂有机物、重金属和硫酸盐的废水的生物电化学技术提供了新的思路。
