Premium
Simultaneous removal of COD and NH 3 ‐N in secondary effluent of high‐salinity industrial waste‐water by electrochemical oxidation
Author(s) -
Huang YaoKun,
Li Shuang,
Wang Can,
Min Ji
Publication year - 2012
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.2692
Subject(s) - effluent , electrochemistry , chlorine , chemistry , pollutant , chemical oxygen demand , electrode , current density , kinetics , wastewater , degradation (telecommunications) , inorganic chemistry , nuclear chemistry , environmental engineering , environmental science , organic chemistry , telecommunications , physics , quantum mechanics , computer science
Abstract BACKGROUND: Electrochemical oxidation has been applied successfully in industrial waste‐water treatment. The simultaneous removal of COD Cr and NH 3 ‐N, as well as the corresponding mechanisms and reaction zone, were examined in this study. The reaction kinetics and the significant factors that affect removal performance were also studied. RESULTS: The COD Cr removal efficiency without chlorides in waste‐water was only 11.8% after 120 min of treatment, which was much lower than the efficiency with chlorides, and agitation did not improve the performance. When the current density was increased from 2.5 to 10 mA cm −2 , the removal efficiency was improved. The removal efficiencies of COD Cr and NH 3 ‐N were less at initial pH = 11 than at pH = 3 and 8.7 (without adjustment). The COD Cr and NH 3 ‐N removal efficiencies were decreased by about 30% and 50%, respectively, when the electrode distance was increased from 4 to 12 cm. Instantaneous current efficiency decreased with increase in current density. CONCLUSIONS: The degradation of pollutants occurred mainly at the boundary layer between the electrode and the bulk solution. The indirect oxidation by active chlorine generated from the chlorides was proven to be the primary mechanism of electrochemical oxidation treatment. The removal of COD Cr in this study followed a pseudo‐first‐order kinetic model. Copyright © 2011 Society of Chemical Industry