Study On Exogenous Promoter For Manure Biogas Fermentation At Cold Region

Biogas is currently the most promising renewable energy in rural areas,as China is a large agricultural country,rich agricultural wastes as raw materials for the biogas production.And the relative maturity of fermentation technology to reduce environmental pollution,reduce burdens of fuel,reduce carbon emissions,protect and improve the ecologlical environment has played a huge role.However,there are some common problems of the actual operation of the digester,biogas production significantly reduced mainly in the cold regions and cold season.Temperature is one of the main factors influencing the biogas fermentation,the temperature dropped to a certain extent,microbial activity will be severely inhibited.The existing research is mainly aimed at psychrophilic methanogens,and less for low temperature condition combinations and exogenous additives research.In order to improve the performance of low temperature anaerobic fermentation and the rate of producing gas,the paper using cow dung,studied on fermentation about adding corn stovers,cellulose enzyme,trace elements,metal chelating agents and adsorbent as exogenous experimental study of the accelerator under low temperature 15?,through different dosing quantity and the method of orthogonal test,by investigating the changes in gas production,and then pick out the best dosing quantity and the best proportion.According to the change trend of COD,volatile fatty acid(VFA),coenzyme F420,carboxymethyl cellulose(CMC)enyzme activity,explore the influence of exogenous accelerators for the cow dung anaerobic fermentation processes of low temperature,to improve the biogas fermentation at low temperature has certain guiding significance.Experiment was conducted through the cow manure and corn straw mixed in different proportions(1:1,2:1 and 3:1)to anaerobic fermentation under low temperature 15 ?,gas production rates of cow manure and com stalk 1:1 ratio is highest,relativing to the proportioning ratio of 2:1,3:1 increased by 34.5%and 42.4%.With fermentation processes,large fluctuations change in COD,cow manure and corn stalk 1:1 ratio during the early fermentation of COD reach the top,13851.7 mg/L.VFA has a certain correlation between daily gas production,acid accumulation will be utilize at the late fermentation.Coenzyme F420 has no significant relationship between daily gas production.CMC enzyme activity change significantly.The effects on anaerobic fermentation by adding different amount of cellulose 0,0.25,0.5,0.75 and 1.0g.L-1 with cow manure under low temperature 15 ? showed that adding cellulose groups all have two gas production peak,the cellulose content of 0.75g · L-1 of gas production rates is highest,total gas production rates of adding cellulose groups are increased 15.3%,7.1%,18.8%,7.1%relative to blank group.Each groups of VFA peak period behind the gas production peak;The change trend of coenzyme F420 synchronization in gas production;The peak of CMC enzyme activity is slightly ahead of gas production changes.Adding cellulose at middle can restart anaerobic fermentation stages of hydrolysis.Experiment was conducted by using the cow manure as fermentation substrates at low temperature 15? with orthogonal experiment in three factors and three levels of the Fe,Mn,Ni.The following conclusion:.the optimal process parameters combination for Fe(50 mg.L-1),Mn(150 mg.L-1),Ni(40mg.L-1).Under the condition of the process gas production rate is highest,the maximum value of 177 ml.Trace element Fe can accelerate the launch manure anaerobic fermentation in low temperature,the excessive addition of trace elements will inhibit methanogens produce methane.The more the amount of Mn added,the greater the gas production;the amount of Ni and gas production is also a positive correlation,but smaller rise late;Under different process conditions,the daily gas production and VFA showed a certain relationship,trace element Fe promote the generation of VFA.Experiment was conducted by adding two different chelating agents about ethylenediamine tetraacetic acid(EDTA)(25g ·L-1 and 50g · L-1)and citric acid(CA)(15g·L-1 and 30g·L-1)anaerobic fermentation under low temperature 15 ?.The experiment showed that adding a chelating agent of each group compared with the blank group gas production increase 4.43%,3.56%,25.52%,33.10%.The chelation of trace elements and chelating agent can increase the concentration of the trace elements in fermented liquid,and EDTA chelation of Ni and not play a role in low temperature.Chelating agents can dissolve fatty acid accumulation,activate the activity of methanogens,promote the hydrolysis macromolecular organic matter decomposition,so as to improve the performance of anaerobic fermentation.The effects on anaerobic fermentation by adding different amount of activated carbon(0?5?10?15g·L-1)anaerobic fermentation under low temperature 15? showed that the amount of active carbon is positive correlations between daily gas production.The content of activated carbon that is 15g ·L-1 has the highest total gas production rate,adding activated carbon groups compared with the blank group increased by 150%,190%,195%and 237%.Activate carbon increased microbial contact areas.the stages for the fermentation of microorganism provide a good environment,greatly improve the gas production of cow manure anaerobic fermentation at low temperature.The low yield of COD and gas production rate is higher;Activated carbon can prevent acid accumulation;Coenzyme F420 relationship with gas production was not significant;Cellulose enzyme activity and the gas production rate has certain correlation.The success of this project successfully implemented,will further to solve the problem of rural biogas fermentation in winter,breaking through the bottleneck of "low temperature"biogas fermentation,realize high methane production under the condition of low temperature processes,not only can greatly broaden the application of biogas fermentation technology,but also has important practical significance to promote rural recycling,protecting and improving the rural ecological environment,the promotion of biogas careers promoting sustainable development and building a conservation-oriented society.