Characteristics Of Nonthermal Plasma Catalysis Reactor Coupled With Bio-Trickling Filter For Chlorinated VOCs Treatment

Recently,environmental problems caused by volatile organic compounds?VOCs?have received more and more attention.As a new technology,the Non-thermal plasma catalytic technology coupled with Bio-trickling filter process?NTP+BTF?has good potential for treating non-biodegradable VOCs and high concentrations of VOCs.In this paper,the performance of 1,2-DCA degradation by the catalyze of Non-thermal plasma technology was investigated,as well as the combination of this technology and Bio-trickling filter treatment process.Using CuO/MnO₂ as target catalyst,the effects of the inlet concentration,residence time,discharge voltage on decomposition efficiency of 1,2-DCA were investigated and the decomposition products were analyzed.The results showed that the removal efficiency of 1,2-DCA increased with an increasing discharge voltage or residence time.Increasing the initial concentration of the gas into the plasma reactor resulted in decreasing the removal efficiency of 1,2-DCA with and without catalyst,but removal amount increased.In addition,during the analysis of degradation products,we found that O3,COx and intermediate products were the main products of 1,2-DCA degradation.Ozone is considered as an unavoidable byproducts produced by air plasma reactor.The concentrations of ozone rised as the discharge voltage increased.As expect,a noticeable decrease in the O3 concentration was observed in the presence of CuO/MnO₂ catalyst relative to plasma alone.The presence of catalysts could oxidize the by-products such as nitrogenous organics,which leads to a higher CO2 selectivity.Besides,the pretreatment technology resulted in greater enhancements of solubility and biodegradability of byproducts,which provided the fundamental data to evaluate the feasibility of the combined system.There are two BTFs which were setted up with 1,2-DCA as sole carbon source,directional domesticated activated sludge and high efficient degradation bacteria as inoculation fluid.Experimental results showed that two BTFs biofilm were able to finish cultivation within 16 d.After start-up period,the Non-thermal plasma catalytic technology was accessed to the system as pretreatment compared with single BTF system.The performance of the degradation by coupling system and single BTF system were analyzed under different operation conditions.The removal efficiency of two systems had a trend of decline with the increase of inlet concentration.The removal rate of single BTF system changed significantly when the experimental conditions changed compared with the coupling system,indicating coupling process showed better removal performance.It mainly owe to some small molecules produced by NTP pretreatment which had good water solubility and can be degraded easily by microorganism.The amount of CO2 improved with the increase of 1,2-DCA removal loading,the mineralization rate of coupling system was 92% which was higher than single BTF.BTFs were also used to remove the mixture waste gas of 1,2-DCA and n-Hexane nd showed that the removal efficiencies of 1,2-DCA and n-Hexane both decreased as the inlet n-Hexane concentration increased,under the condition of the inlet 1,2-DCA concentration remaining steady.However,when the inlet n-Hexane concentration increased to 800mg·m-3,the 1,2-DCA biodegradation was relatively inhibted with the total removal rate of 1,2-DCA reduced to 82% from 95% in single BTF,while,the removal rate of 1,2-DCA stayed above 90% with the coupling system.Compared with the single BTF,our coupling system could reach a high elimination capacity under the same constraints,indicating that coupling system BTF strengthened by Non-thermal plasma catalytic technology was superior to the traditional BTF.BTF was operated without carbon source provided.The result showed that after starvation period of 21 days,the coupling system could restore stability in 11 days,while single BTF system needed 16 days.The high-throughput sequencing was used to research biofilm microbial population structure and diversity.The results showed that the dominant bacterial community still existence along with the running of the reactor.The NTP pretreatment had a certain influence on microbial community structure.Also,it showed that the microbial diversity and abundance of the coupling system were lower than that of single BTF system,which may be due to the O3 produced by NTP pretreatment that has inhibitive effect on microorganisms in BTFs.