The concentration of solids in secondary sludge before anaerobic digestion in a wastewater treatment plant, bring about the production of a return flow, which contains high concentrations of all the common pollutant parameters. This return flow could unfavourably affect the performance of the processes and effluent quality of the waterline. Here, we report the utilisation of three similar microbial electrolysis cells reactors that performs simultaneous carbon and nitrogen removal to reduce the impact of the return flow in the plant. The result of the batch-fed (72 h) experiment showed COD and total nitrogen removal efficiencies that reached 90% and 80%, respectively, supporting the premise that return flows are suitable substrates for a bioelectrochemical treatment. The three reactors followed similar trends, showing good replicability and confirming the potential of MECs as a feasible technology for return flow treatment. Furthermore, when cathodic conversion efficiency was higher than 80%, the pure hydrogen production allows to recover the electric energy consumption, indicating that the system could be theoretically energy neutral.

在废水处理厂进行厌氧消化之前，二次污泥中的固体浓度导致产生回流，该回流包含高浓度的所有常见污染物参数。该回流会不利地影响过程的性能和输水管线的出水水质。在这里，我们报告了三个类似的微生物电解池反应器的利用，该反应器可同时进行碳和氮的去除，以减少工厂中回流的影响。分批进料（72小时）实验的结果表明，COD和总氮去除效率分别达到90％和80％，这支持了回流是生物电化学处理的合适底物的前提。这三个反应堆也遵循类似的趋势，显示出良好的可复制性，并确认了MEC作为回流处理的可行技术的潜力。此外，当阴极转化效率高于80％时，纯氢气的产生可以回收电能消耗，这表明该系统在理论上可以是能量中性的。