Treatment of pharmaceutical wastewater using interior micro-electrolysis/Fenton oxidation-coagulation and biological degradation. (June 2016)

• Record Type: Journal Article
• Authors: Xu, Xiaoyi; Cheng, Yao; Zhang, Tingting; Ji, Fangying; Xu, Xuan
• Is Part Of: Chemosphere. Volume 152(2016)
• Page Start: 23
• Page End: 30
• Publication Date: 2016-06
• Subjects: Interior micro-electrolysis -- Fenton oxidation -- Biological contact oxidation -- Pharmaceutical wastewater -- Field experiment; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2016.02.100
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The synthesis of steroid hormones produces wastewater that is difficult to manage and characterize due to its complex components and high levels of toxicity and bio-refractory compounds. In this work, interior micro-electrolysis (IME) and Fenton oxidation–coagulation (FOC) were investigated as wastewater pretreatment processes in combination with biological treatments using a hydrolysis acidification unit (HA) and two-stage biological contact oxidation (BCO) in laboratory and field experiments. In laboratory experiments with an average initial COD load of about 15, 000 mg/L, pH of 4, Fe–C/water (V/V) ratio of 1:1, air/water ratio of 10, and reaction time of 180 min, IME achieved a COD removal efficiency of 31.8% and a 1.7-fold increase in the BOD5 /COD (B/C) ratio of wastewater. The Fe 2+ concentration of 458.5 mg/L in the IME effluent meets the requirements of the Fenton oxidation (FO) process. FOC further reduced the COD with an efficiency of 30.1%, and the B/C ratio of the wastewater reached 0.59. Excitation-emission matrix (EEM) analysis showed that complex higher molecular weight organic compounds in the wastewater were degraded after the pretreatment process. In addition, a field experiment with a continuous flow of 96 m 3 /d was conducted for over 90 d. The combined process system operated steadily, though the Fe–C fillings should be soaked in a sulfuric acid solution (5‰) for 12 h to recover activity every two weeks. The COD and BOD5 concentrations in the final effluent were less than 90 mg/L and 15 mg/L, respectively. Highlights: IME–FO lab-scale tests and IME–FOC–biological treatment full-scale experiments were conducted. Optimal parameters were obtained and the BOD5 /COD of wastewater improved 2.8 times after pretreatment. IME effluent with appropriate pH and high Fe 2+ concentration was suitable for the FO process. The combined system had a high pollutant removal efficiency and good operating stability.