Pivotal Parameter Optimization And Mechanism Research Of High Efficient Methane Production From Biomass

As the fourth largest energy in the world,bioenergy is an effective supplement of fossil energy for the advantages of renewability and low pollution.At the same time,biomass wastes were reused with bioenergy recovery,the environmental benefits was good.Biomass can be used for methane production which is consisted of forestry wastes,agricultural wastes,and urban and industrial organic wastes.Poplar and vegetable are widely planted in the western China,the amount of residues produced during the processing is large,such as poplar processing residues(PPW)and vegetable processing wastes(VPW).Current treatment of these wastes not only caused serious pollution for local environment,but also resulted in the waste of a large amount of biomass resources.For the fragile and aridly ecological environment of the western,the study of anaerobic digestion with high methane production and economization of water resource is very important.According to the characteristics of these biomass,especially for the PPW that was not used for methane production previously,key parameters of high efficient methane production were obtained,effective energy conversion of biomass resources was realized.In this study,we investigated the efficiency of methane production from PPW and VPW based on the characteristics of these two materials.PPW contains high content of lignocellulose,after NaOH treatment,we tested various fermentation technologies to improve the methane production of PPW.The results are as follows:1.Alkaline treatment improved the degradation of PPW.The results indicate that the time used for treating PPW 'by alkaline was only 5 days.After treatment,pH(7.5)of the treated materials was suitable for later anaerobic digestion.The maximal degradation of lignin was 20.5%.Scanning electron microscopy(SEM),FTIR spectra and Crystallinity measurements showed that the lignocellulosic structures were disrupted by NaOH treatment.2.Key factors of high methane production of liquid-state anaerobic digestion of PPW alone were obtained.The maximum methane production(271.9 L/kg VS)was obtained at conditions of 35 g/L after 5.0%NaOH treatment,which was 113.8%higher than untreated one.However,methane production of 3.0%NaOH at the same concentration was 256.6 L/kg VS and was only 12.1%less than the maximal methane production.Considering the cost efficiency,the 3.0%dose of NaOH was optimum for application.The results indicate PPW might be an efficient substrate for methane production after NaOH treatment.3.We modified solid-state anaerobic digestion of lignocellulosic materials.The results show that alkaline treatment can improve the methane production of solid-state anaerobic digestion of PPW alone effectively.When the mixture ratio of PPW and CS was 1:1,the maximum methane production(98.2 L/kg VS)was obtained,which was 21.1%higher than that of PPW alone.These results provided theoretical foundation for the research and application of anaerobic digestion that is suitable for arid region.We have also investigated the process stability and the methane production of VPW+CS.For VPW,the lignocellulose content was low and the water content was high.1.Key factors of high methane production of liquid-state anaerobic digestion of mixtures(VPW+CS)were obtained.For a certain concentration(5.0%),the process of anaerobic digesiton of mixtures was stable with C/N ratio remained between 19:1 and 16:1.For a certain C/N ratio,the process stability was enhanced with the increase of inoculum proportion in mixtures,and then the improvement of methane production.The results indicate that C/N ratio is important for the stability of anaerobic digestion of VPW.2.Key parameters of anaerobic digestion of mixtures(VPW+CS)at high substrate concentration was obtained.When 1%,V%and TS%were 40%,35%and 7.9%,respectively,the methane production was maximum(186.8 L/7kg VS),the methane content was 73.1%-88.0%.Methane production of VPW alone was ceased during the initial period of anaerobic digestion.As a result,the quality of biogas of anaerobic digestion at high substrate concentration was high(high methane content);no water addition in the anaerobic digestion of VPW+CS,which is suitable for arid region;the capacity of treating VPW was.large.These results provide important references for the research and application of anaerobic digestion that is suitable for arid region.For WS which has been studied extensively.In order to further improve the efficiency of methane production of WS,three synthetic compounds that could significantly improve the methane production of liquid-state anaerobic digestion of WS alone and mixtures(WS+CS)were obtained.The result shows that the process stability and methane production of anaerobic digestion of mixtures were improved by T2.This type of synthetic compound has the advantages of convenient transportation,easy preservation,environmental protection,low cost and wonderful effect.In summary,after research of methane production with three types of biomass resources as main feedstock,key parameters of high efficient methane production of PPW,VPW and WS were optimized,which provide essential reference for the rational application and development of bioenergy technology in the field of agriculture,forestry,animal husbandry and breeding industries,and the guiding influence exerted on the environmental construction in country is significant.