Fabrication Of New Biological Fillers Based On PVA&SA And Research On Purifying Toluene Waste Gas

Biological methods are widely applied in the treatment of volatile organic compounds（VOCs）because of its low consumption,environmental friendliness and low operation difficulty.Among them,fillers play an important role as the carrier of microorganisms in the biotrickling filtration（BTF）,at present,some traditional fillers still have some disadvantages such as low strength,bad surface characteristics and less nutrients.Therefore,in order to strengthen the ability of BTF to treat VOCs,in this study,PVA（Polyvinyl Alcohol）granulation filler and PVA attached filler were developed and manufactured with large specific surface area and nutrient sustained-release function,so as to enhance the surface characteristics,nutrient release function and VOCs purification ability.The composition ratio of the two fillers was determined by response surface curve method and orthogonal experiment,then two fillers were characterized and tested.Finally,toluene was used as a simulation of VOCs gas to study the ability of the two fillers to treat toluene and the microbial composition of the filler surface.The conclusions are as follows:1)The optimal composition ratio of PVA granulation filler determined by response surface experiment was PVA 9.07%,sodium alginate 4.00%,fertilizer 20.00%,activated carbon 6.32%,calcium carbonate 2.00%;The optimal composition ratio of PVA attached filler with polyurethane foam as carrier determined by orthogonal experiment was 4.00%PVA,6.00%sodium alginate,4.00%citrate fertilizer,1.00%activated carbon and 2.00%calcium carbonate.2)Compared with the traditional fillers,the biggest characteristics of the PVA granulation filler and the PVA attached filler are large specific surface area and high saturated water content.The average specific surface area is 274.63 m²·g^-1 and 654.52 m²·g^-1,respectively,and the average saturated water content is 125.00%and 185.76%,respectively.The performance analysis shows that the two new fillers have the ability of nutrient slow release and good thermal stability at the experimental temperature.The presence of hydrophilic groups makes the two fillers have good hydrophilicity.The organic solvent has little influence on the two fillers,but the strong acid and strong alkali environment will cause certain damage to the two fillers.3)Compared with the PVA granulation filler without nutrients,when the toluene intake concentration was 100～200 mg·m^-3,the PVA granulation filler with nutrients was started in8 days,and the maximum toluene removal rate was 96.32%,which proved that the start-up time and efficiency of BTF was shorter and higher after the slow-release component was added.The addition of nutrient slow-release components is beneficial to the rapid start-up of BTF.4)Compared with polyurethane foam tower,the PVA attached filler tower showed a higher and more stable toluene purification capacity.The maximum toluene elimination capacity of PVA attached filler tower was 38.39 g·（m³·h）^-1,and the toluene removal rate was 17～40%higher than that of polyurethane foam tower at different stages.When the external nutrient supply is stopped,the toluene removal rate of the PVA attached filler tower can be more than 80%for at least 30 days.After the hunger stage,the removal rate of toluene is 23.68%on the first day of start-up,18.14%higher than that of polyurethane foam packed tower,and the recovery time is also shorter.5)Microbial analysis showed that the abundance of bacterial species in the PVA attached filler tower was higher than that of fungi.Due to the higher abundance of bacteria in Proteobacteria and Burkella,the PVA attached filler tower had higher toluene purification capacity than the polyurethane foam tower.