Study On Biointensification For Biogas Fermentation

Biogas producing systems were widely used in industry and agricultural areas which induced its wide application in biointensifciation.But there were some tough problems in the biogas production process such as slow start-up and low productivity. Faced on this,some researches on improving biointensification according for the mechanism of biogas fermentation were taken in this paper.The mian contents and resultes as follows:1.Adding hydrogen producing bacteria:hydrogen producing bacteria could speed up the rate of hydrogen production,and facilitate the growth of methanogens and production of methane.A hydrogen producing strain,Clostridium sp.3-9,was used to biointensificaton for a biogas producing system.The time of start-up in the biogas producing system was obviously shortened at least three days.Meanwhile,this strain accelerated accumulation of organic acid including acetate and propionate in this system.The results showed that Bacteroides,Rikenella,Clostridiaceae, Desulfobulbaceae,Acholeplasma and Proteiniphilum were dominnat populations in ths system by sequencing bands of 16S rDNA PCR-DGGE fingerprinting.2.Adding homogenate of termites:Termit is one of the most important degraders of lignocellulose in nature ecosystem.There are abudance of microorganism and enzyme involving degradation and conversion of lignocellulose in termites and their commensal interstinal micrflora.These microorganism and enzyme could be use to intensify biogas producing systems by adding homogenate of termites.In this study, endoglucanse,β-glucanse,xylanase and fiter paper activity in head,body and gut of solider and worker termites(Coptotermes formosanus) were compared,which indicated most part activity of all enzymes remained in body and gut of the termite and all enzymes activity of the worker termite were obviously higher than those of the solider termiter.Homogenate of the worker termites could significantly improve the performance of a biogas producing system.The volume of gas and methane was increased by 91.7%and 79.2%,respectively.3.Isolation of both aerobic and cellulolytic bacteria from biogas system:both aerobic and cellulolytic bacteria can accelerate start-up of biogas fermentation by establishing anaerobic conditions for anaerobic bacteria and facilitating degradation of ceUulose.At first,a both aerobic and cellulolytic strain Streptomyces sp.c3001 was isolated by selective medium after enrichment under aerobic and static condition. Then this strain was identified to belong to Streptomyces according to 16S rDNA analysis.At last,a specific sequence of the strain was obtained by cloning band of ERIC-PCR fingerprinting,which might be used as a biomarker for monitoring the strain during biointenfication.4.A high-thoughput method was established for screening endoglucanse, exoglucanse,β-glucanse and xylanase positive clones in a metagenomic library of biogas system.These cellulose positive clones screened from the metagenomic library might provide suitable cellulase for biointenfication of biogas producing systems.Above all,there were two methods used in intentifing biogas producing system were developed,and provided some fundamental works for further researching in this paper.