电催化厌氧消化能增强CO2生化还原比例,得到更多甲烷,因而成为备受关注的电产甲烷关键技术之一。其过程中造成碱度在沼液中积累,不利于电催化厌氧消化的连续稳定运行,阻碍了技术应用。在每一个底物投加批次内除去上批次积累的碱度,可以将pH值稳定在电催化厌氧消化适宜的6.0~8.6,使系统得以稳定运行。该研究通过对不同浓度的乙酸投加量进行了对比研究,乙酸一方面能中和沼液中的碱度,另一方面也作为产甲烷过程的底物。实验结果表明,以11 667 mg/L的乙酸为底物时,电催化厌氧消化反应器能够稳定运行且能够显著提升甲烷含量,使产气中最高甲烷含量达到96.88%,平均池容产气率为1.442 m3/(m3·d),批次产气中的平均甲烷含量达到80.59%。经实验数据验证,以乙酸为唯一底物的电催化厌氧消化表观反应方程式显示CH3COOH、CH4、(HCO3-+CO32-)和CO2的物质质量比为7∶8∶5∶1。
Electrocatalytic anaerobic digestion can enhance the ratio of biochemical reduction of CO2 and obtain more methane, thus becoming one of the key technologies of electric methane production that has attracted much attention.Its process causes alkalinity to accumulate in the digestate, which is detrimental to the continuous and stable operation of electrocatalytic anaerobic digestion and hinders the application of the technology.Removing the alkalinity accumulated in the previous batch within each substrate dosing batch can stabilize the pH value between 6.0 and 8.6, which is suitable for electrocatalytic anaerobic digestion, and enable the system to operate stably.In this study, a comparative study was carried out by dosing different concentrations of acetic acid, which on one hand neutralized the alkalinity in the digestate and on the other hand acted as a substrate for the methanogenic process.Results showed that the electrocatalytic anaerobic digestion reactor was able to operate stably and significantly increase the methane content when 11 667 mg/L acetic acid was used as the substrate, resulting in the highest methane content of 96.88% in the produced gas, the average pool gas production rate was 1.442 m3/(m3·d), and the average methane content in the batch of the produced gas was 80.59%.As verified by the experimental data, the apparent reaction of electrocatalytic anaerobic digestion with acetic acid as the only substrate showed that the substance mass ratios of CH3COOH, CH4, (HCO3- +CO32-), and CO2 were 7∶8∶5∶1.
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