Study On The Efficiency And Mechanism Of The Removal Of VOCs By Rhamnolipid Enhanced Biotrickling Filter

The organic pollutants VOCs in atmospheric pollutants had different carbon chain lengths and most of them were slightly soluble or insoluble in water.Therefore,the biological efficiency of microbial treatment was reduced and the biomass accumulation cycle was prolonged,which limited industrial application of biotrickling filter.In this study,two identical biotrickling filter towers(BTF1 and BTF2)were used to inoculate the sludge extracted from the furniture factory and domesticated.Added rhamnolipid to BTF2,and used BTF1 as a control(without adding rhamnolipid).Under the same conditions,studied the influence of rhamnolipid on biotrickling filter start-up and biomass changes.The characteristics of the biofilm and microbial flora in the tower during the stable operation of the trickling filter tower were studied,and the stability of the two trickling filter towers at different inlet air concentrations was compared,and analyzed the strengthening mechanism of the effect of rhamnolipid on the degradation of ethylbenzene by the trickling filter.The study found that when the concentration of rhamnolipids was 21.6 mg/L,the promotion of microbial growth in BTF was particularly obvious,and the amount of rhamnolipids was directly metabolized.BTF2 with 21.6 mg/L of rhamnolipids added 39.62 mg/g more BTF1 than the BTF1 on the 35 th day,and there was no blockage of the trickling filter during operation.In addition,the removal efficiency of ethylbenzene in the BTF2 was 12% higher than that in the BTF1 during the stable operation period.The addition of rhamnolipid enhanced the biodegradation efficiency of ethylbenzene by the biotrickling filter tower and accelerated the formation of biofilms in the trickling filter tower.The study found that when the concentration of rhamnolipids was 21.6 mg/L,the promotion of microbial growth in BTF was particularly obvious,and the amount of rhamnolipids was directly metabolized.BTF2 with 21.6 mg/L of rhamnolipids added 39.62 mg/g more BTF1 than the BTF1 on the 35 th day,and there was no blockage of the trickling filter during operation.In addition,the removal efficiency of ethylbenzene in the BTF2 was 12% higher than that in the BTF1 during the stable operation period.The addition of rhamnolipid enhanced the biodegradation efficiency of ethylbenzene by the biotrickling filter tower and accelerated the formation of biofilms in the trickling filter tower.Through the impact test of the biotrickling filter with different intake air concentration,it was found that when the intake concentration of ethyl bromide in the addition of rhamnolipid biotrickling filter tower BTF2 was 600 mg/m3,900 mg/m3 and 1200 mg/m3 besides EBRT was 102 s,the removal efficiency of ethylbenzene was 89%,85%,and 80%,respectively;while the degradation efficiency of BTF1 in the control group was reduced to 77%,68%,and 46%.This showed that the addition of rhamnolipid biotrickling filter showed a good resistance to load impact.Further studies showed that the relative hydrophobicity of the filler biofilm in BTF2 supplemented with rhamnolipids was enhanced,and the relative hydrophobicity of BTF2 biofilm reached 89.7% at the 120 th day of the trickling filter operation,while BTF1 was only 68.2%.This showed that the addition of rhamnolipid could increase the hydrophobicity of the biofilm inside the tower,facilitate the bioavailability of hydrophobic organic matter,and accelerated the transfer of hydrophobic organic substances between the gas phase and the water phase,thereby increased the stability and degradation efficiency of the biotrickling filter system.The structure and diversity of microbial communities in BTF1 and added rhamnolipid BTF2 were analyzed by using the high-throughput sequencing technique for 16 SrDNA analysis on biofilms.As a result,it was found that the microbes in the rat rhamnolipid BTF2 system were more densely distributed on the ceramsite.The community composition of BTF1 and BTF2 were basically the same,and the main dominant flora was Proteobacteria spp,followed by Cyanobacteria spp,Acidobacteria spp,Actinobacteria spp,Firmicutes spp,and Bcateroidetes spp.In the BTF2,proteobacteria accounted for 81.9% of all the bacteria,while it provided only 62.3% in the BTF1.The addition of rhamnolipid to BTF system could promote the enrichment and growth of dominant bacteria,enhance the degradation of ethylbenzene by BTF system,and increase the removal efficiency and stability of BTF.This study found that the strengthening of the biotrickling filter column by rhamnolipids could accelerate the formation of biofilms,increase the efficiency and stability of ethylbenzene degradation in biotricklintowers,enhance the anti-load capacity of the filter towers,and promote the toweg filter r It also promote the enrichment of microbial flora in the tower.