Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6306925 | Chemosphere | 2016 | 8 Pages |
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 15,000Â mg/L, pH of 4, Fe-C/water (V/V) ratio of 1:1, air/water ratio of 10, and reaction time of 180Â 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 Fe2+ concentration of 458.5Â 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 96Â m3/d was conducted for over 90Â d. The combined process system operated steadily, though the Fe-C fillings should be soaked in a sulfuric acid solution (5â°) for 12Â h to recover activity every two weeks. The COD and BOD5 concentrations in the final effluent were less than 90Â mg/L and 15Â mg/L, respectively.
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Authors
Xiaoyi Xu, Yao Cheng, Tingting Zhang, Fangying Ji, Xuan Xu,