Research On Bioaugmentation Of Biotrickling Filter By Microbial Agents For Enhancing Removal Of Sulfur Malodor

Emissions of toxic volatile organic compounds and malodorous gases?such as sulfur malodor?from oil refining,pharmaceutical,chemical and other industries have been a serious environmental and health concern in recent years.The technologies for treating such gases have also been more and more important.In this paper,an experimental investigation on purification of waste gas contaminated with a mixture of dimethyl sulfide?DMS?and propanethiol?PT?was conducted in biotrickling filter?BTF?inoculated with activated sludge and a formulated microbial agents comprising of Alcaligenes sp.SY1 and Pseudomonas putida S-1,which had a high removal efficiency of dimethyl sulfide?DMS?and propylmercaptan?PT?,respectively.PT had a significant inhibitory effect on the biodegradation of DMS has been found in the experiment of simultaneous biodegradation of DMS and PT by SY1 and S-1 strains,while citric acid could stimulate the biodegradation of DMS under the presence of PT.Strains S-1 and SY1 could enlarge culture by Luria-Bertani?LB?and mineral medium?MM?with DMS and yeast,respectively,which resulted from their different growth characteristics and removal performance.The best ratio of wood chips to activated carbon was 6:1 to prepare microbial agents,this microbial agents had a good removal performance of DMS,PT and H₂S as well,and it could be preserved as long as 90 days.The removal performance,biomass and microbial community structure of BTF in start-up process and steady state were studied.H₂S removal capacity in the steady state of BTF were studied as well.The results showed that BTF inoculated with the microbial agents could get increased removal efficiency and it was proved with greater removal performance and higher stability for mixe gas contaminated with a mixture of DMS and PT than the control group,which just inoculated with activated sludge.The experiment groups could successfully start up within 11 days,which greatly reduce the startup time,the stable removal efficiency?RE?of DMS and PT were 90%and 100%respectively.The mineralization rate of mixed gas of experimental groups stabled at 73.5%.The interaction test indicated that PT had a significant inhibitory effect on the bio-oxidation of DMS when the inlet concentration of PT more than 51 mg·m^-3,while DMS had no inhibitory effect on PT-biodegradation even the inlet concentration of DMS more than 103 mg·m^-3.Meanwhile,the BTF also had good performance of starvation-endurance and H₂S removal.The removal cfficiencies of H₂S of experimental groups were 98%even the inlet concentration was 230 mg·m^-3,which were higher than the control group's as well.The high-throughput sequencing results showed that many kinds of microbial populations existed in biological trickling filter system,the experimental group amount which Pseudomonas,Alcaligenes and Thiobacillus account for a high and stable proportion,while microbial populations in control group mainly Pseudomonas and Thiobacillus,based on which we might conclude that DMS was mainly removed by Alcaligenes and Thiobacillus,PT mainly by Pseudomonas.The experimental results show that the formulated microbial agents is expected to be as bioaugmentation applied to treat odorous gases by biotrickling filter.