Study On Removal Of Toluene By Horizontal Biotrickling Filter

In this paper,the horizontal biotrickling filter was designed by ourselves to perform toluene elimination research related to process and microecology.High-quality ceramics with size of 10-12 mm was used for packing and the dominant fungus screened from the activated sludge was used for microfloras source.Starting up the horizontal biotrickling filter inoculated the dominant fungus achieved a toluene removal rate of more than 90%in about 3 days.In addition,the biofilm formation was analyzed and discussed in the initial stage of start-up.Besides,when the empty bed resident time was longer than 32.8s and the toluene inlet concentration was about 330 mg/m~3,the total toluene removal rate was close to 100%.After changing the inlet direction of the reactor,the overall performance of the reactor has been improved,mainly in the presence of high toluene concentrations.And commutation helped to regulate the distribution of microorganisms in the packing area and improved the flow of gas,thus reducing the pressure drop of the reactor.In addition,the trends in temperature of inlet,outlet,and intermediate in the reactor were basically the same.Besides,the intermediate temperature was lower than the outlet temperature and higher than the inlet temperature.The major degradants of the toluene waste gas in the horizontal biotrickling filter were the fungus of Aplanochytrium which belonging to Thraustochytriaceae family and Labyrinthulomycetes phylum,Boletellus which belonging to Basidiomycota phylum,Exophiala which belonging to Ascomycota phylum.Besides the fungus,there were many other eukaryotes in the reactor such as rotifers,nematodes and so on.What’s more,the diversity of microbial communities in the anterior segment of the reactor was always higher than that the posterior segment of the reactor.And after the commutation,the diversity of the microbial communities in both the anterior and posterior segments was reduced.In addition,the major fungus of toluene degradaters were Aplanochytrium and Boletellus before the commutation,and that was Exophiala after the commutation.With the increase of the toluene concentration,the trends in relative abundance of fungus degrading toluene varied from before the commutation to after the commutation as well as from the anterior segment to the posterior segment of the reactor.When the reactor was resumed after having stopped for a short period of time,the microbial activity recovered rapidly and good performance could be restored after3 days.After the reactor was stopped,the diversity of microbial communities in the anterior and posterior segments increased,and the trends in relative abundance of fungus degrading toluene were similar in the anterior and posterior segments.After the reactor was restarted,the diversity of microbial communities and the trends in relative abundance of fungus degrading toluene were reduced in the anterior segment.And the diversity of microbial communities and the trends in relative abundance of fungus degrading toluene were increased in the posterior segment.Besides,the microecology changing of the anterior segment under stopping or restarting operation was more significantly than that of the posterior segment of the reactor.