Enhanced removal of refractory organic pollutants from high-salinity mining wastewater by E-peroxone process

CHEN Anni; GUO Qiang; YIN Yanying; LI Jingfeng; BAO Yixiang; WU Min; YI Shizuo; WANG Jianbing; WANG Huijiao

doi:10.13225/j.cnki.jccs.2024.0582

Abstract：High-salinity mining wastewater is produced in the process of zero discharge.Due to its complex composition and high organic concentration,its treatment has become a worldwide problem.Hence,it is urgent to develop efficient technologies to remove refractory organics from high-salinity wastewater.E-peroxone process is a novel advanced oxida-tion process,and its advantages of high efficiency,good flexibility,and environmental friendliness make it a promising technical option for deep removal of organics from high-salinity wastewater.In term of this,this study firstly analyzed or-ganic compounds in a high-salinity mining wastewater from western China with gas chromatography-mass spectrometry(GC-MS).A total of 15 organic compounds were detected,and they can be divided into three species,that is,macrocyclic siloxanes,esters,and nitriles and amides.Among them,dimethyl phthalate(DMP),an ester compound,showed a high peak signal,with its peak area accounting for 20.38%.Hence,DMP was selected as the characteristic compound of the high-salinity mining wastewater to investigate its removal kinetics and reaction mechanism in the E-peroxone process,based on which the technical and economic feasibility of E-peroxone process for the treatment of practical high-salinity wastewater was further explored.Results show that DMP was difficult to be efficiently removed by conventional ozona-tion due to its relatively low ozone reactivity.In contrast,by electrochemically in-situ generating hydrogen peroxide in conventional ozonation,the E-peroxone process obviously increased the hydroxyl radical(·OH)concentration in the reac-tion system by 1 order of magnitude,and thus significantly accelerated and enhanced the removal of DMP in the solution.Further theoretical calculations show that the C4 and C8 sites on the benzene ring of DMP are the dominant reaction sites for·OH attack,and transformation products of this reaction pathway were also detected.For the treatment of practical high-salinity mining wastewater,the E-peroxone process also exhibited the highest organic mineralization efficiency and the lowest energy consumption compared with conventional electrolysis and ozonation.Therefore,the results of this study demonstrated the technical and economic feasibility of the E-peroxone process for deep removal of organics from high-sa-linity wastewater,showing a promising application potential.