Effect Of Methanogenic Cultures For Bioaugmentation On Chicken Manure Anaerobic Digestion

Anaerobic digestion technology has been widely used in the treatment of livestock manure.When chicken manure is used as a single raw material for anaerobic digestion,the ammonia nitrogen concentration of the fermentation broth is high during the fermentation process,which inhibits the activity of the methanogenic culture in the system,resulting in an imbalance between the anaerobic digestion acid-production and methanogenesis stages,accumulation of volatile fatty acids,and methane production decline.In this paper,bioaugmentation with methanogenic culture was used to the batch anaerobic digestion experiment of chicken manure,and the effect of different dosages of methanogenic culture on the anaerobic digestion of chicken manure was investigated,the optimal bacterial group dosage within a certain range was also determined.Then the optimal dosage was applied to the continuous digestion experiment of chicken manure,to explore the promotion effect of bioaugmentation on the performance of continuous fermentation under different organic loads,and the performance difference of the bioaugmented reactor before and after the suspension of methanogenic culture suspension.In addition,the mechanism of bioaugmentation was revealed from the aspects of microbial community composition and succession.The main conclusions are as follows:?1?In the batch experiment of anaerobic fermentation of chicken manure,the fermentation performance,fortification effect and microbial community of different methanogenic bacterial groups were compared.The result shows:At different dosages of methanogenic culture,the methane production of batch anaerobic digestion has increased,and the greater the dosage.The bioaugmented reactors with added dosages of 0.07,0.14,0.21,0.27,and 0.34 g VS_BS/g VS_CM,respectively,the accumulative methane production was 1.2,1.7,2.2,3.4,and 3.6 times of the control reactor,and the bioaugmentation efficiency was 265,392,426,643 and 566 mL g^-1 VS_BS.The optimal dosage was 0.27 g VS_BS/g VS_CM.The system with this dosage has the fastest degradation rate of acetic acid,the highest biofortification efficiency and the shortest methane generation time;microbial community analysis shows that bioaugmentation mainly changes the dominant methanogenic community in the system.Methanobacterium was the predominant culture and with the progress of anaerobic digestion,the abundance was gradually increasing.?2?In the semi-continuous experiment of anaerobic fermentation of chicken manure,the gas production performance,fermentation process parameters and microbial community analysis were compared with or without bioaugmentation,and the study found that:Compared with the non-bioaugmented system,the methane production performance and volatile acid degradation of bioaugmented reactor have been significantly improved.During the stable operation period of experiment?31-240 d?,the average daily methane production of the bioaugmented reactor accounted for 70.7%of the theoretical methane production,an increase of 12.1%over the un-bioaugmented reactor.The composition of the dominant community of archaea has changed;The dominant methanogens evolved to Mathanobacterium,with relative abundance in the range of 58-81%.The methane production,pH value and the changes of ammonia nitrogen concentration had little effect.During the period of stable operation?31-180 d?of the regular dosage of methanogenic culture,the daily methane production increased by 40.1 mL g^-1 VS,the volume methane production increased by 0.22 L L^-1 d^-1,and the methane content increased 0.3%;during the stable operation period?181-240d?,the daily methane production r was increased by 35.4 mL g^-1 VS,the volume methane production was increased by 0.14 L L^-1 d^-1,and the methane content increased 1.3%.The bioaugmentation reactor did not change the composition of the community before and after the suspension of the bacterial community,and still maintained the abundance of the dominant methanogenic community.