Experimental Study On Green Technology Of Combined Treatment Of Printing Tail Gas VOCs By Biological Method And Absorption Method

Volatile organic compounds（VOCs）is one of the common pollutants in the atmosphere,direct emission will cause a great threat to the atmospheric environment and human health,in order to realize the harmless treatment of VOCs in the printing tail gas,improve the resource recycling efficiency,the development of a printing tail gas VOCs green treatment process route is very important.Absorption method is widely used in industrial waste gas treatment because of its large processing capacity and high efficiency,but the wastewater produced by absorption method contains esters and alcohols,which will also lead to environmental pollution.Considering the biological wastewater treatment method has the advantages of low cost,no secondary pollution,if can combine with the absorption,by optimizing the process conditions and equipment structure absorber of VOCs in exhaust gas absorption efficiency and realizes the biological sorbent regeneration,for printing and exhaust emissions of target,zero discharge of wastewater and the recycling of water resources is of great significance.In this study,ethyl acetate and butyl acetate in the printing tail gas were used as models.The VOCs tail gas was first treated by absorption method,and water was used as absorbent to investigate the absorption effect of water on VOCs under better technological conditions.Then,chlorella was used to treat and absorb waste liquid,and the effects of environmental factors and domestication on VOCs in chlorella degradation wastewater were investigated.The removal effect of VOCs from wastewater by immobilization of chlorella and recycling of chlorella were investigated.The absorption method and biological method were combined to build the gas phase microalgae adsorption tower to further purify the low concentration of printing tail gas VOCs.The main work of this paper is as follows:（1）The experimental study on the treatment of printing tail gas VOCs by absorption method was carried out.Ethyl acetate and butyl acetate in tail gas were absorbed in a packed column using water as absorbent.The experimental results show that the removal rates of ethyl acetate and butyl acetate can reach 94.41%and 90.05%,respectively,when the absorption liquid temperature is 2℃,the spray volume is 0.16L/min,the gas intake is 10 L/min,and the concentration of VOCs in the tower is500-600 mg/m³.（2）The effects of environmental factors and domestication of algae species on the removal efficiency of ethyl acetate and butyl acetate by Chlorella were investigated.The immobilization conditions of chlorella were determined by orthogonal experiment and the cycling performance of chlorella was investigated.The results showed that ethyl acetate and butyl acetate could be completely degraded in 4days and 3 days respectively when the initial algae density OD₆₈₀value was 0.2,the initial VOCs concentration was 150 mg/L and the initial p H of the medium was 7.After domestication,chlorella can obviously improve the removal efficiency of both.Through orthogonal test,the immobilized conditions of Chlores were determined as follows:4%sodium alginate solution,3%calcium chloride solution,calcification time 6 h.Under these conditions,the removal ability of VOCs of chlores prepared was slightly higher than that of suspended algae.The removal rate of ethyl acetate and butyl acetate decreased with the increase of algal pellets.（3）A gas-phase microalgae adsorption column was constructed to treat low concentration of tail gas VOCs.The ratio of packing and algal pellets was determined as 1:3.When the nutrient solution spraying amount was 50 m L/min,the removal rates of ethyl acetate and butyl acetate were 66.91%and 62.07%,respectively.On the basis of the above experiments,a green treatment process for printing tail gas VOCs was developed.