Detection of 4-Nitrophenol, a Model Toxic Compound, Using Multi-Stage Microbial Fuel Cells
Detection of 4-Nitrophenol, a Model Toxic Compound, Using Multi-Stage Microbial Fuel Cells
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DOI：
10.3389/fenvs.2020.00005
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发表时间：
2020-01
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影响因子：
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通讯作者：
Alexiane Godain;M. Spurr;H. Boghani;G. Premier;E. Yu;I. Head
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作者：
Alexiane Godain;M. Spurr;H. Boghani;G. Premier;E. Yu;I. Head
对生物处理过程中存在的生物量的上游保护是一项重大挑战，因为失败的后果可能包括水用户接触危险化学品以及处理性能的损失。在线检测废水中的有毒化合物可以使过程得到实时监测，并促进对污染事件的积极反应。近年来，微生物燃料电池（MFCs）利用有机物氧化产生电能，显示出作为在线检测毒性的传感器的潜力。在这项研究中，检测模型毒物（4-硝基苯酚）进行了研究，使用多级MFC为基础的毒性传感器。MFC与合成废水一起运行，以保持现实的条件，同时能够控制有机碳水平。在4-NP浓度和当前滴面积之间观察到正相关性，表明响应与毒性水平成比例。此外，传感器阳极生物膜表现出对急性毒性事件的恢复力，在包含500 mg/L 4-NP的毒性事件后4 h恢复初始电流的75%。然而，重复的毒性事件可能导致选择能够降解有毒化合物的耐药细菌。在本研究中，观察到最大4-NP降解速率为36 mg/h。这一限制可以通过在确定数量的毒性事件后重新校准来克服。传感器的多级配置的另一个特征是，由有毒化合物的存在引起的输出下降可以与由BOD的降低引起的输出下降区分开。传感器阳极上的微生物群落的特征在于16 S rRNA基因测序，并显示出包括能够产生挥发性脂肪酸和氢的发酵细菌的厌氧群落，所述挥发性脂肪酸和氢被在传感器中产生电信号的产电地芽孢杆菌属（2.76至21.39%的阳极群落）消耗。多级MFC生物传感器可以提供一个预警系统，能够提醒过程操作员的存在和进水废水中的毒性水平。
The upstream protection of the biomass present in biological treatment processes is a vital challenge as the consequences of failure could include exposure of water users to hazardous chemicals in addition to loss of treatment performance. Online detection of toxic compounds in wastewater could enable processes to be monitored in real-time and promote pro-active responses to pollution incidents. Recently, Microbial Fuel Cells (MFCs) which generate electricity from organic matter oxidation have shown potential as sensors for online detection of toxicity. In this study, the detection of a model toxicant (4-nitrophenol) was investigated using a multi-stage MFC-based toxicity sensor. MFCs were operated with synthetic wastewater to maintain realistic conditions while enabling organic carbon levels to be controlled. A positive correlation was observed between the 4-NP concentrations and the current drop area showing that the response was proportional to the toxicity level. In addition, the sensor anodic biofilm exhibited resilience to acute toxic events with recovery of 75% of the initial current following a toxic event comprising 500 mg/L 4-NP after 4 h. However, repetitive toxicity events could lead to the selection of resistant bacteria able to degrade the toxic compounds. In this study, a maximal 4-NP degradation rate of 36 mg/h was observed. This limitation could be overcome by re-calibration after a determined number of toxic events. An additional feature of the multi-stage configuration of the sensor is that a drop in output caused by the presence of a toxic compound could be distinguished from a drop in output caused by a decrease in BOD. The microbial community on the sensor anode was characterized by 16S rRNA gene sequencing and shown to comprise an anaerobic community of fermentative bacteria capable of producing volatile fatty acids and hydrogen that were consumed by electrogenic Geobacter spp (2.76 to 21.39% of the anode community) that generated the electrical signal in the sensor. The multi-stage MFC biosensor could provide an early warning system capable of alerting process operators to the presence and level of toxicity in influent wastewater.