title: Treatment of pharmaceutical wastewater using interior micro-electrolysis/Fenton oxidation-coagulation and biological degradation.
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.
authors.affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China. Electronic address: xuxiaoyi@cqu.edu.cn.
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Xu
authors.affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China.
authors.forename: Fangying
authors.initials: F
authors.lastname: Ji
authors.affiliation: Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Xu
mesh_terms: D057919:Biological Oxygen Demand Analysis; D004345:Drug Industry; D004572:Electrolysis; D006868:Hydrolysis; D007220:Industrial Waste; D007501:Iron / Q000737:chemistry; D010084:Oxidation-Reduction; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry
chemical_list: D007220:Industrial Waste; D007501:Iron; D062065:Wastewater
keywords: Biological contact oxidation; Fenton oxidation; Field experiment; Interior micro-electrolysis; Pharmaceutical wastewater