Advanced treatment of biotreated coking wastewater with peroxymonosulfate oxidation catalyzed by granular activated carbon

BACKGROUNDAfter biological treatment, coking wastewater contains high concentrations of toxic organic contaminants and thus requires further treatment. RESULTSAdvanced treatment of biotreated coking wastewater (BTCW) with peroxymonosulfate (PMS) oxidation catalyzed by granular activated carbon (GAC) at ambient temperature (25 degrees C) was comprehensively investigated. The GAC/PMS system exhibited higher efficiency for total organic carbon (TOC) removal from BTCW than did the PMS-only and GAC-only systems. Up to 75.7% of TOC was removed over a 5 h period with 2 g L-1 of KHSO5 and 10 g L-1 of GAC at an initial pH of approximately 5. The TOC removal efficiency increased with PMS concentration and GAC dosage; however, the superfluous PMS was not conducive to organic degradation. The PMS decomposition followed a first-order kinetics behavior. The GAC/PMS system's capacity for TOC removal gradually weakened with increase in the number of times the GAC was reused. Almost half of the removal rate was retained after four uses of GAC. The excitation-emission matrix fluorescence demonstrated that humic-acid-like substances are effectively adsorbed and preferentially decomposed in wastewater. CONCLUSIONThe study suggests that it is feasible for advanced treatment of BTCW with PMS oxidation catalyzed by GAC, achieving high efficiency for TOC removal. (c) 2017 Society of Chemical Industry