Hydraulic retention time (HRT) is one of the most important factors to be analyzed and optimized in continuous flow operations such as the integrated process of microbial electrosynthesis system (MES) and anaerobic digestion (AD). Highest methane production rate of 12.2 ± 0.1 mmol/L_(feed)-d was obtained at 18-h HRT with reject water feed that was supplemented with acetic acid. Highest amount of COD removal of 23.4% was obtained at 18-h HRT operation with the reject water feed that was not supplemented with acetic acid. The pH of the effluent was 8.63 and 7.64 at 18-h HRT for both the feed types, respectively. This resulted in net alkalinity reduction implying conversion of bicarbonate to methane at 90% of biogas. It was also observed that the electrochemical methane production rates were higher in feeds that were not supplemented with acetic acid along with additional COD degradation via direct electro-oxidation of organics at anode.

水力停留时间（HRT）是在连续流动操作（例如微生物电合成系统（MES）和厌氧消化（AD）的集成过程）中要分析和优化的最重要因素之一。最高产甲烷率12.2±0.1 mmol / L _（进料）-d在HRT 18小时时得到，废水进料中补充了乙酸。在HRT运行18小时的情况下，使用不添加乙酸的废水进料，最高可去除23.4％的COD。对于两种进料，在18 h HRT时废水的pH分别为8.63和7.64。这导致净碱度降低，这意味着在90％的沼气中碳酸氢盐转化为甲烷。还观察到，在未补充乙酸的进料中，随着阳极上有机物的直接电氧化，COD的降解会增加其电化学甲烷的产生速率。