| The strain which had the ability to utilize toluene as a sole carbon source was screened and then induced by UV radiation and LiCl, The mutant which has 4.8% higher toluene-degradation efficiency was further identified as Pseudomonas sp. ZD5A.A laboratory biofilter was designed to purify low-concentration gaseous toluene and VOCs in which the Pseudomonas sp. ZD5A was inoculated on its medium. Four kinds of medium(wood block medium, cortex medium,ceramic loop medium and stainless steel loop) were used in the experimental program and the wood block medium was found to be the best one.For the biofilter(φ5 x 13cm) with wood block medium,toluene removal efficiency at an inlet concentration of less than 700mg/m3 was greater than 90% under the conditions that the temperature was 30℃,the inlet flux was 0.01m3/h, relative moisture of the medium was 80% and pH=7.0.The operating parameters were optimized for two biofilters(φ15x25cm and φ 15x67cm) filled with wood block medium of which porosity was 0.57. For the biofilter(φ15x25cm),when the temperature was 30℃,the inlet flux was less than 0.3m3/h, relative moisture of the medium was 80% and pH=7.0, the toluene removal efficiency at an inlet concentration of less than 3000mg/m3 was greater than 90%. For the biofilter(φ15x 67cm),when the temperature was 30℃,the inlet flux was less than 0.5m3/h, relative moisture of the medium was 80% and pH=7.0, toluene removal efficiency at an inlet concentration of less than 5000mg/m3 was greater than 87%.Based on the process of purifying gaseous low-concentration toluene,the biodegradation mechanism and the new Adsorption-Biofilm theory,a Kinetic model was set up.In further simulation study for the main factors,such as the inlet toluene concentration,the gas flux and the height of biofilm-packing,a good pertinence was showed between calculated data and test data. |
