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近年来,水体突发性重金属污染事故频发,严重威胁受污染流域附近的生态平衡和居民健康[1]。微生物燃料电池(MFC)传感器为水体突发性重金属污染的预警提供了一个新的思路[2-4]。水样中重金属物质的生物毒性会抑制MFC传感器阳极上电活性微生物的新陈代谢过程,宏观表现为MFC传感器输出电信号减弱,并可通过计算电信号抑制率(inhibition ratio,IR)进行量化分析[5-7]。MFC传感器在一定程度上具有能量自持、信号直观和自我修复等功能[8-10],故在水体重金属物质的监测预警方面具有较好的实用性。
MFC传感器在应用于监测预警时,仍然存在2个问题。1)水样中存在的可生化降解有机物(biodegradable organic matter, BOM)会使MFC传感器监测预警信号出现假阴性问题。为了提高MFC传感器对水样中BOM波动的抗干扰能力,JIANG等[11]采用氧还原混合菌生物阴极作为MFC传感器的敏感元件来监测水样中的甲醛,相较于传统的生物阳极敏感元件可有效解决乙酸造成的假阴性问题,但仅可用于好氧水体的监测;SPURR等[12]构建了一种新型的三级MFC传感器,可定性地区分BOM含量下降和毒性物质抑制作用所导致的MFC传感器输出电信号减弱的情况。2)重金属毒性会给电活性微生物造成不可逆损伤[13-15],使MFC传感器信号重现性变差。有研究[16-18]利用无机化合物(二氧化硅、碳酸钙、多层聚合电解质等)对电活性微生物活细胞个体进行包裹,以此维持反应器的长期稳定运行,但这些物质也会对微生物电化学传感器的输出电信号造成干扰。
针对上述MFC传感器监测假阴性问题和信号重现性差问题,本研究采取预先使阳极上的电活性微生物在监测时间内恰好处于营养饱和状态的方案,并采用监测时间内的库仑量(coulombic yield,CY)的抑制率作为预警信号指标,利用单室MFC搭建了单程连续流模式实时原位监测装置,以Cr(Ⅵ)为目标污染物,评估传感器的预警性能,分析外加不同浓度乙酸钠与不同种类外源BOM对Cr(Ⅵ)冲击预警稳定性的影响,探索MFC传感器对3次相同浓度Cr(Ⅵ)冲击的信号重现性,为MFC传感器实时原位监测水体重金属污染提供参考。
基于微生物库仑量抑制率的水体重金属污染监测方法
Monitoring method of heavy metal pollution in water based on inhibition ratio of microbial coulomb
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摘要: 为实现对水环境重金属污染的实时原位监测,利用单室微生物燃料电池(microbial fuel cell,MFC)传感器搭建了单程连续流装置,并对其预警稳定性进行了探讨。结果表明:以Cr(VI)作为目标污染物,MFC传感器的检出限为0.4 mg·L−1,在0.2~1 mg·L−1的质量浓度区间内,库仑量抑制率与Cr(VI)质量浓度具有较高的共变趋势;设定模拟废水中Cr(VI)的质量浓度为1 mg·L−1,MFC传感器对乙酸钠质量浓度分别为384.62、480.77和576.92 mg·L−1的模拟废水预警的库仑量抑制率为34.71%±1.65%、36.60%±3.82%和36.28%±10.64%;对分别含有谷氨酸、乳酸和蔗糖(质量浓度均为50 mg·L−1)的模拟废水预警的库仑量抑制率为35.22%±6.51%、37.05%±3.74%和24.23%±1.90%,这说明MFC传感器对水样中的可生化降解有机物具有一定的抗干扰能力; MFC传感器连续3次对含有1 mg·L−1 Cr(VI)模拟废水预警的库仑量抑制率为35.37%±3.21%、39.48%±0.95%和41.50%±4.24%,证明MFC传感器的预警信号重现性较好。以上研究结果可为MFC传感器实时原位监测水体重金属污染提供技术参考。
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关键词:
- 微生物燃料电池传感器 /
- 重金属污染 /
- 库仑量抑制率 /
- 实时原位监测
Abstract: In order to realize the real-time in-situ monitoring of heavy metal pollution in the water environment, a single-chamber microbial fuel cell (MFC) sensor was used to build a single-pass continuous flow device, and its early warning stability was discussed. The results showed that with Cr(VI) as the target pollutant, the detection limit of the MFC sensor was 0.4 mg·L−1, the coulomb inhibition ratio had a high linear correlation with the mass concentration of Cr(VI) in the range of 0.2~1 mg·L−1. In addition, the mass concentration of Cr(VI) in the simulated wastewater was set as 1 mg·L−1, and the coulombic inhibition rates of MFC sensors for the simulated wastewater with the sodium acetate mass concentrations of 384.62, 480.77 and 576.92 mg·L−1 were 34.71%±1.65%, 36.60%±3.82% and 36.28%±10.64%, respectively. The coulombic inhibition rates for the simulated wastewater samples containing glutamic acid, lactic acid and sucrose (all concentrations were 50 mg·L−1) were 35.22%±6.51%, 37.05%±3.74% and 24.23%±1.90%, respectively, this results showed that the MFC sensor had a certain anti-interference ability to biodegradable organic matter (BOM) in water samples. Finally, for the early warning of simulated wastewater containing 1 mg·L−1 Cr(VI), the coulombic inhibition rates of MFC sensors were 35.37%±3.21%, 39.48%±0.95% and 41.50%±4.24% for three consecutive times, respectively, this results showed that the early warning signal of the MFC sensor had good reproducibility. The above research provides a technical reference for the real-time in-situ monitoring of heavy metal pollution in water by MFC sensors. -
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