Abstract Upflow anaerobic sludge blanket (UASB) systems are of specific interest for the treatment of high organic wastewater since they offer the opportunity to recover energy in the form of methane (biogas). The technology is highly suitable for the degradation of biodegradable organics, but its efficiency can be significantly hampered by the presence of toxic pollutants in the water. In this study, the use of electrochemical advanced oxidation (eAOP) coupled to a lab-scale UASB reactor for the degradation of 4-chlorophenol (4-CP) in wastewater was investigated. The eAOP treatment consisted of the electrochemical production of active chlorine at a Ti/RuO2–IrO2 anode with a fixed current density of 25 mA/cm2 in the recycle of the UASB reactor. It was noticed that the total COD removal efficiency decreased from 75.8% when no 4-CP was present in the wastewater to 25.6% and 13.6% after the addition of 100 ppm and 50 ppm 4-CP, respectively. Furthermore, elevated levels of volatile fatty acids and ORP were observed in the effluent of the reactor, indicating process failure. It was postulated that the decrease in COD removal efficiency was due to the release of high amounts of hypochlorite, causing an oxidative environment in the anaerobic reactor. This hypochlorite may have reacted with several components such as ammonia to form other toxic components (e.g., chloramine).

中文翻译：

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电化学高级氧化对处理含 4-氯苯酚废水的上流式厌氧污泥床 (UASB) 反应器长期运行的影响

摘要 上流式厌氧污泥床 (UASB) 系统对处理高有机废水具有特殊意义，因为它们提供了以甲烷（沼气）形式回收能量的机会。该技术非常适合降解可生物降解的有机物，但水中有毒污染物的存在会严重影响其效率。在这项研究中，研究了电化学高级氧化 (eAOP) 与实验室规模的 UASB 反应器结合用于降解废水中的 4-氯苯酚 (4-CP)。eAOP 处理包括在 UASB 反应器的循环中以 25 mA/cm2 的固定电流密度在 Ti/RuO2-IrO2 阳极电化学生产活性氯。注意到总 COD 去除效率从 75 下降。当废水中不存在 4-CP 时，分别为 8%，在添加 100 ppm 和 50 ppm 4-CP 后分别为 25.6% 和 13.6%。此外，在反应器的流出物中观察到挥发性脂肪酸和 ORP 水平升高，表明工艺失败。据推测，COD 去除效率的降低是由于大量次氯酸盐的释放造成了厌氧反应器中的氧化环境。这种次氯酸盐可能与几种成分（例如氨）反应形成其他有毒成分（例如氯胺）。据推测，COD 去除效率的降低是由于大量次氯酸盐的释放造成了厌氧反应器中的氧化环境。这种次氯酸盐可能与几种成分（例如氨）反应形成其他有毒成分（例如氯胺）。据推测，COD 去除效率的降低是由于大量次氯酸盐的释放造成了厌氧反应器中的氧化环境。这种次氯酸盐可能与几种成分（例如氨）反应形成其他有毒成分（例如氯胺）。