Removal of organic matter from pre-treated domestic sewage in anaerobic biological reactor by a combined system of electrolytic and biological aerobic treatment

Abstract Biological processes are the most widespread methods for wastewater treatment. However, they are limited in their ability to degrade toxic and refractory pollutants, contaminants that electrochemical processes can remove. Therefore, this research explored the possibility of treating sewage by an anaerobic biological process followed by an aerobic system integrated to an electrolytic process. Three sequential batch reactors were operated in an automated way. Each of three reactors represented a process: aerobic biological treatment (BR); electrolytic treatment (ER); and a combination of both, the bio electrolytic reactor (BER). Two phases were ran with different electrodes: (Phase 1) stainless steel and (Phase 2) graphite. The electric current was varied from 0.001 to 0.100 A. COD, TS, SS, turbidity, and the zooplankton community were monitored. The highest organic matter removal efficiencies were 86%, 79% and 87% for BR, ER and BER, respectively. The best weekly BER efficiencies for COD removal were 90% and 98%, with current densities of 0.27 A/m2 (Phase 1) and 0.05 A/m2 (Phase 2). The main conclusions about bio electrolytic process were: (1) it did not achieve organic matter removal high enough to justify its application; (2) inert electrodes are the more indicated; and (3) the zooplankton community was affected by the electric current.

摘要 生物处理工艺是当前应用最为广泛的污水处理技术。然而，此类工艺在降解有毒难降解污染物方面存在局限，而这类污染物可通过电化学工艺去除。为此，本研究探索了采用厌氧生物工艺，辅以与电解工艺整合的好氧系统处理污水的可行性。本研究设置三台全自动运行的序批式反应器，分别对应三种处理工艺：好氧生物处理反应器（BR）、电解处理反应器（ER）以及两者联用的生物电解反应器（BER）。实验分为两个阶段，分别采用不同电极：第一阶段使用不锈钢电极，第二阶段使用石墨电极；电流设置范围为0.001至0.100 A。实验监测指标包括化学需氧量（COD）、总固体（TS）、悬浮固体（SS）、浊度以及浮游动物群落。好氧生物处理反应器、电解处理反应器与生物电解反应器的最高有机物去除率分别为86%、79%和87%。生物电解反应器在化学需氧量去除方面的最优周度去除率分别达90%与98%，对应电流密度分别为0.27 A/m²（第一阶段）与0.05 A/m²（第二阶段）。针对生物电解工艺的主要结论如下：（1）该工艺的有机物去除率未达到足以支撑其实际应用的标准；（2）惰性电极更为适宜选用；（3）浮游动物群落会受到电流的影响。