Sun Hao, Angelidaki Irini, Wu Shubiao, Dong Renjie, Zhang Yifeng
Key Laboratory for Clean Renewable Energy Utilization Technology, Ministry of Agriculture, College of Engineering, China Agricultural University, Beijing, China.
Department of Environmental Engineering, Technical University of Denmark, Lyngby, Denmark.
Front Microbiol. 2019 Jan 15;9:3357. doi: 10.3389/fmicb.2018.03357. eCollection 2018.
Acetate as the dominant fraction of volatile fatty acids (VFAs) is an important intermediate in metabolic pathways of methanogenesis, which could reflect the stability status of anaerobic digestion (AD) process. Bioelectrochemical sensors for environmental or bioprocess monitoring have become increasingly attractive in recent years. Although it was more favorable, several challenges still need to be addressed for acetate detection, including large electrode spacing, low stability, biofouling at the cathode and low detection range. In this study, an innovative biosensor on the basis of a three-chamber microbial electrochemical system was proposed to monitor the acetate during the AD process. In such a system, acetate was first transferred from sample chamber through the anion exchange membrane (AEM) to anode due to the driven force of concentration difference and then oxidized by anodic biofilm as a substrate for the current generation. With such design, the influence of waste properties fluctuation in the cathodic reaction could be avoided. The response of current density to different acetate concentrations was investigated. The selectivity, the influence of the sample temperature and the external resistance were also evaluated. The correlation ( > 0.99) between the current densities and acetate concentrations (up to 160 mM) was established at specific reaction time (from 2 to 5 h). Current densities after 5 h reaction were improving about 20% when the sample temperature was high (e.g., 37 and 55°C). The detection range increased along with the decrease of external resistance. The acetate concentrations of AD effluents as determined by the biosensor where within 24.2% of the ones determined by gas chromatography. Nevertheless, the application of the biosensor for monitoring acetate in environmental samples could still be promising.
乙酸作为挥发性脂肪酸（VFAs）的主要成分，是甲烷生成代谢途径中的重要中间体，能够反映厌氧消化（AD）过程的稳定性状态。近年来，用于环境或生物过程监测的生物电化学传感器越来越受到关注。尽管其优势明显，但乙酸检测仍面临一些挑战，包括电极间距大、稳定性低、阴极生物污染以及检测范围窄等问题。本研究提出了一种基于三室微生物电化学系统的创新型生物传感器，用于监测AD过程中的乙酸。在该系统中，由于浓度差的驱动力，乙酸首先从样品室通过阴离子交换膜（AEM）转移到阳极，然后被阳极生物膜氧化，作为产生电流的底物。通过这种设计，可以避免阴极反应中废物性质波动的影响。研究了电流密度对不同乙酸浓度的响应。还评估了选择性、样品温度和外部电阻的影响。在特定反应时间（2至5小时）内，建立了电流密度与乙酸浓度（高达160 mM）之间的相关性（>0.99）。当样品温度较高（例如37和55°C）时，反应5小时后的电流密度提高了约20%。检测范围随着外部电阻的降低而增加。生物传感器测定的AD流出物中的乙酸浓度在气相色谱测定值的24.2%以内。尽管如此，该生物传感器在监测环境样品中的乙酸方面仍具有应用前景。
