Construction Of Composite Microbial Agents And Its Bioaugmentation Effects In Thetreatment Of Mixed VOCs

Recently,purification of Volatile Organic Compounds?VOCs?became a stubborn task in waste gas treatment and attracted great attentions of the researchers.In consideration of the great prospect of biological air purification technology and the lack of microbial agents for waste gas treatments,this study aimed at the removal of mixed VOCs through bioaugmentation and the degrading strains which were obtained.This study tested the biodegradation efficiencies and microbial constructions of single microbial strain-mixed compounds systems,mixed strains-single compounds systems and mixed systems.The results revealed that the biodegradability of fungal strains Aspergillus fumigatu HD2,Ophiostoma stenoceras LLC and bacterial strain Zoogloea resiniphila HJ kept immune in a mixed system.Based on four ratios of carrier materials?activated carbon,wheat bran and sawdust were 1:1:1;2:1:1;1:2:1;1;1:1:2,marked separately as No.1,2,3,4?,the composite fungal-bacterial agents were constructed to degrade mixed waste gases containing three different kinds of contaminants??-pinene,n-butyl acetateand o-xylene?.No.3 achieved best in the biodegradability tests.The best results,5.26 mg?-pinene·g^-1_protein·d^-1,12.81mg n-butyl acetate·g^-1_protein·d^-1,and 7.57mg o-xylene·g^-1_protein·d^-1,were obtained at the initial concentration of 120 mg·L^-1.Comparing the agent and fungal&bacterial suspension,significant advantages of the agent were found after starving period,that is,the specific biodegradation rate of?-pinene and o-xylene were 2.85 times and36.45 times more than thatof suspension.SEM?scanning electron microscope?and Pyrosequencinganalysis revealed significant promotion of microbial diversity after the construction of agents and the inoculated strains dominated in the agents.Then,the agents'biodegradabilities after preservation were test,No.3 performed best under room temperature after 180 days storage.Its degradation rates in the first24 hours were 48.2%,95.1%and 57.3%for?-pinene,n-butyl acetateand o-xylene respectively.Referring to the 4?preservation,the degradation rates of No.4 agent for?-pinene,n-butyl acetateand o-xylene were 41.8%,88.9%and 42.1%respectively,which were the best among the agents and far more better than the fungal&bacterial suspension?being preserved in the same condition and the results were 20.4%,79.7%and 18.9%,respectively?.As a conclusion,by constructing microbial agents,the survival rate and degradation activity of microorganism were maintained.And under both of the two conditions,the agents can be preserved for longer than 180 days.Finally,No.3 agent inoculated into a biofilter?reactor No.1?to test its performances,which were compared with another biofilter inoculated with sludge?reactor No.2?.The elimination capacities of No.1 for?-pinene,n-butyl acetateand o-xylene were 149.65 g·m^-3·d^-1,170.55 g·m^-3·d^-1 and 146.98 g·m^-3·d^-1,respectively.Its performances were much better than No.2 with the different values of 57 g·m^-3·d^-1,10 g·m^-3·d^-1and 62 g·m^-3·d^-1,respectively.The achievements showed the composite microbial agents can shorten the start-up period,and enhance the stability and degradability.