Study On The Components And Removal Characteristics Of Pollutants In Semi-coking Wastewater Treatment Processes

Semi-coking wastewater contains large amounts of refractory, highly toxicpollutants, such as benzene, phenols, polycyclic aromatic hydrocarbons, heterocycliccompounds and heavy metals and other pollutants. It is a typical industrial waste withhigh pollution and highly toxic. In order to clarify the composition, concentrations andgenotoxicity of pollutants in semi-coking wastewater. The presence of pollutants insemi-coking wastewater was analyzed by using GC and ICP-MS. Then, their removalcharacteristics were explored in the actual wastewater treatment processes. Andgenotoxicity of each stage of the water treatment were analyzed by micronucleus test.The results show that thirty-nine kinds of pollutants were detected of the selectedfifty-four kinds of pollutants in semi-coking wastewater. It Contains thirty-one kinds oforganic pollutants and eight kinds of heavy metal pollutants. Eight kinds of BTEX areall detected and their total content in semi-coking wastewater is111.09mg/L. Theconcentration of fourteen kinds of detected phenols is3350.88mg/L.The concentrationof phenol is the largest in phenols and it is1333.44mg/L.The concentration ofdimethyl phenol is1137.24mg/L. The concentration of nitro phenol is90.56mg/L andthe concentration of chlorophenol concentration is510.64mg/L. Five kinds ofpolycyclic aromatic hydrocarbons are detected in wastewater and their total content is1335.62mg/L. The concentration of naphthalene is1328.04mg/L. Four kinds ofheterocyclic compounds are all detected and their total content is23.68mg/L. Also,eight kinds of heavy metals are all detected and their total content is14.95mg/L.During the treatment process, extraction treatment unit can have high removaleffect of BTEX, phenols and polycyclic aromatic hydrocarbons. Their removalefficiencies respectively are74.4%,91.7%and72.1%. Removal effect of BTEX, phenols, heterocyclic compounds is significant inbio-chemistry treatment stage. BTEX is mainly removed by aerobic biodegradationpathways and its removal efficiencies respectively is95.8%. The removal efficienciesrespectively of phenols is80.7%, and the removal efficiencies respectively of phenolsin anaerobic, aerobic treatment unit are53.8%and58.4%. anaerobic treatment unit canhave high removal effect of Phenol, nitrophenol and aerobic treatment unit can havehigh removal effect of Methyl phenol. Removal effect of Phthalic acid dibutyl, indoleand quinoline is significant in anaerobic treatment unit and their removal efficienciesrespectively are57.4%,81%and89.5%. Removal rate of Pyridine is lower inbio-chemistry treatment stage.Sedimentation treatment unit can have high removal effect of phenols andpolycyclic aromatic hydrocarbons. Their removal efficiencies respectively are88.9%and94.7%.Adsorption treatment unit can have high removal effect of BTEX, phenols andpolycyclic aromatic hydrocarbons. Their removal efficiencies respectively are93.8%,99.4%and97.0%.During the treatment process, micronucleus frequency gradually increases fromextraction processing unit to precipitation processing unit and their micronucleusfrequency are2.13‰,2.64‰,3.16‰,3.32‰and4.28‰. All of them are Lower thanthe micronucleus frequency of negative control group((7.43‰). The micronucleusfrequency of sedimentation treatment unit is largest and it is15.68‰. The genotoxicityof sedimentation treatment unit is higher than negative control group. The water canhave significant toxic effects on organisms. After adsorption treatment, thegenotoxicity of adsorption treatment unit can reduce to a considerable level of negativecontrol group, and its micronucleus frequency is8.06‰It can have no significantgenotoxicity effects.The combination process with physicochemical-biochemical techniques workswell in treating semi-coking wastewater. Extraction treatment unit can have largestcontribution for the removal of organic pollutants and its total concentration reducesfrom4584.02mg/L to626.68mg/L. the contribution of adsorption treatment unit islargest for genotoxicity reduceing and the micronucleus frequency reduces from 15.68‰to8.06‰. After employing the process of physicochemical-biochemicaltechniques combination, cod≤100mg/L, phenols≤0.5mg/L and ammonia nitrogen≤15mg/L, which meet which meet The emission standard of pollutants for coking chemicalindustry. The water can have no significant genotoxicity effects.