Advanced Treatment of Biologically Pretreated Coking Wastewater by Electro-Coagulation: Degradation Behavior and Mechanism
Hai Tang1, Jun-Peng Sha1, Gui-Zhong Liu2, Yang-Long Ou1
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1School of Biochemistry Engineering, Anhui Polytechnic University,
Wuhu Anhui 241000, China
2Beijing Municipal Research Institute of Environmental Protection,
Beijing 100083, China
Pol. J. Environ. Stud. 2015;24(3):1355–1362
In the present study, the electro-coagulation (EC) process has been first applied to advanced treatment of biologically pretreated coking wastewater (BPCW), and the degradation behavior and mechanism were investigated by means of a lab-scale EC in static methods. The results showed that the percent COD and color removal can reach 80.5% and 95.4%, respectively, under optimal conditions (initial pH 8.0, reaction time 30 min, current density 14.0 mA/cm2, and NaCl dosage 1.6 g/L). The pseudo-second-order kinetic model fit well with the kinetic data of COD in the treatment of BPCW by EC process. The compositional evaluation of EC flocks and treated wastewater by FT-IR and UV-Vis indicates that the residual organics from BPCW might be removed through electro-oxidation, chemical complexation, and EC sludge adsorption. The energy consumptions per unit of pollutants were obtained as 12.26 kW·h/kg COD (RMB ¥ 6.13 /kg COD). It is proved that the treatment of BPCW using the EC process is very effective with a lower operating cost.