Pollution Control And Health Risk Assessment Of Large Air Volume And Low Concentration Organic Waste Gas Emitted In Typical Chemical Industry

The emission characteristics of organic waste gas in the typical chemical industries are low concentration,large air volume and complex composition.The emission of these organic waste gases not only are involved in the formation of atmospheric secondary aerosol and ozone,but also poses serious harm to human health.Therefore,the efficient removal of organic waste gas from typical chemical industries is very important from the aspects of the environment and human health protection.However,there are still many problems associated with organic waste gas treatment,such as high operation cost,low treatment effect,poor equipment stability and so on.In order to improve the efficiency of waste gas treatment,reduce the operation cost of equipment and give implication for industrial organic waste gas treatment,this thesis systematically study the emission characteristics of organic waste gas,selection and integration of technologies,and operation and evaluation of integrated technologies for organic waste gas treatment in paint production factory and PCB production factory.Attention also paid on the OFP and health risk assessment before and after treatment.:（1）A case study in which an integrated decontamination technique of absorption concentration with catalytic combustion was applied to purify the waste gas emitted from a paint production factory.,it was found that the average concentration of Total Volatile Organic Compounds（TVOCs）in the waste gas emitted from the factories was 173 mg/m~3,includinghydrocarbons（AHs）,halogenated hydrocarbons（HHs）,aliphatic hydrocarbons（AIHs）,and oxygenated VOCs（OVOCs）,and the concentration of AHs,HHs,AIHs and OVOCs was 0.65,0.14,129.3,and 42.92 mg/m~3,respectively.AIHs were the species with the highest concentration（74%）Among all VOCs,the substances with the highest content was methylcyclohexane（concentration of 116.1 mg/m~3）and 2-butanone（concentration of41.73 mg/m~3）.According to the emission characteristics of exhaust gas,the combined technology of runner adsorption-catalytic combustion,which has efficient treatment effect on AIHs,was selected.The average RE of VOCs during the nine months continuous treatment was 97.56%.In addition,OFP and health risk（cancer and non-cancer risks）greatly decreased after ST-PC treatment..These results prove that the runner adsorption-catalytic combustion is not only effective for the removal of the organic waste gas generated by the paint production industry,but also can effectively reduce OFP and reduce carcinogenic and non-carcinogenic health risks.（2）Printed circuit board（PCB）manufacturing industrial emission,characterized with low concentration and high gas flow rates,is one of the important sources of toxic and odorous VOCs,which are deleterious to human health and severed as important precursors for O₃formation.Here,we conducted a case study in which an integrated decontamination technique of spray tower（ST）with photocatalysis（PC）was applied to purify the waste gas emitted from a PCB manufacturer.Total 66 VOCs including HHs,AHs,OVOCs,and AIHs were quantified using GC-MS during four sampling events.AHs were the largest groups（contributing>85.0%of the sum of VOCs）.The average RE of VOCs during the nine months continuous treatment was 72.39%.High RE can be attributed to the following three aspects:the capture efficiency of HHs with slight water solubility（50.16%of RE）and AIHs with low saturated vapor pressure（54.75%of RE）was improved by ST before PC,and AHs was preferentially degraded by PC（61.34%of RE）.However,we also found that the degradation efficiency of halogenated hydrocarbons was low（75%）.In addition,OFP and health risk（cancer and non-cancer risks）greatly decreased after ST-PC treatment.This study suggests that ST-PC technique is a promising approach for removal of continuous exhausted organic waste gas with low concentration and high gas flow rates,as well as alleviating O₃ formation and health risk.（3）With the aim to improve the photodegradation efficiency of HHs over P25,.Mn and Ce doped P25 was prepared,and the Mn and Ce-doped was supported on glass fiber paper by electrophoresis（electrophoresis time was 15 min）.The obtained photocatalyst not only displayed high remove efficiency（90%）for trichloroethylene,but also shown high photocatalytic performance for styrene（83%）and ethyl acetate（80%）.The stability test suggested that the as-prepared catalyst also displayed high stability(continuously running for1600 min without dramatical lost activity.Compared with the undoped Ce and Mn catalysts,the degradation efficiency of the modified catalyst for dichloromethane was increased by 23%and 10%,respectively,and the degradation efficiency of HHs in the mixed gas was increased by 25%and 20%respectively.This result proves that the Ce and Mn doped catalyst exhibit outstanding photocatalytic activity and stability for HHs degradation.