Research On The Improvement Of Methane Production Efficiency Of High Concentration Anaerobic Digestion Under Ammonia Stress Of Rural Organic Household Waste

With the modernization of agricultural countryside,the economic level and living standard of farmers have been greatly improved,accompanied by a large amount of household waste generation.A large amount of household waste improperly treated can pose a threat to the rural environment and human health,and conventional sanitary landfilling and incineration treatment produce secondary pollution.About 40% of the rural household waste is organic part,which provides conditions for it to be resourced and treated harmlessly.It is a significant research to use effective methods deal with ROW.AD could digest organic matter to produce clean energy biogas,and AD with high concentration had the advantages of water saving,large treatment volume,low energy consumption,high output marsh concentration,and easy subsequent treatment of the marsh residue.But there were problems of low mass transfer efficiency,easy acidification of the digestion system,and ammonia nitrogen inhibition.To solve the above questions,this paper firstly analyzed the physicochemical properties by monthly sampling of the domestic waste from the domestic waste sorting and disposal centerat Wang Zhuang village,Daeng street,Xuzhou Peixian,Jiangsu,China,and studied the annual change of ROW in rural areas to prove its feasibility as raw material for biogas engineering.It was solved by the method of preparing nanomaterials with efficient ammonia nitrogen adsorption performance and co digestion with other substrates.And the optimal experimental scheme was expanded to a pilot scale,verifying the reliability of the experimental scheme and its potential application to biogas engineering.The main research content and outcomes are as follows:(1)Through the analysis of the physical and chemical properties of the ROW in the third anniversary of Datun Street,Peixian County,it could be seen that the annual changes of water content,C/N,lignocellulose,TP and TK content were stable,which were directly related to the biogas production potential,and the physical and chemical properties were generally within the range suitable for AD.The 36 month sampling data strongly proves that ROW is suitable as a raw material for AD,and provides more comprehensive data support for the study of AD of ROW.(2)PNPs with high ammonia nitrogen adsorption performance and regeneration ability were successfully prepared,and PNPs could utilize cubic vacancies to capture excess ammonia nitrogen in AD system to achieve the adsorption effect.For the first time.The effect of removing the inhibition of ammonia nitrogen in high-concentration AD of ROW was evaluated,and the adsorption amount of ammonia nitrogen in AD was as high as 71.09 mg/g.After adding PNPs to the digestion system,it could effectively adsorb excess ammonia nitrogen and avoid the phenomenon of ammonia nitrogen inhibition.Each experimental group could produce methane normally,the highest methane production rate can reach 302.22 m L/g VS,and the lowest ammonia nitrogen concentration in the fermentation system is reduced to 1700.77 mg/L.(3)The anaerobic co-digestion characteristics of ROW with different co-digestion substrate ratios and different feed concentrations were studied,so as to optimize the AD process of ROW.In this paper,anaerobic co-digestion of PM and RC from Luhe Animal Experimental Base of Jiangsu Academy of Agricultural Sciences with ROW from Peixian County,Xuzhou City,Jiangsu Province and was carried out.The volume of the AD was 500 m L and the effective volume was350 m L.When the digestion substrates were ROW and PM,the methane production increases with the increase of the total solid content of the feed TS,and the highest was 257.38 m L/g VS.When the digestion substrate were ROW and RC,or ROW,PM and RC,when the mass fraction of TS in the feed increased from 8% to 12%,the methane production increased,with the highest being339.59 m L/g VS and 322.16 m L/g VS,respectively.When the mass fraction of feed TS continued to increase to 15%,the yields of both decreased and were lower than other experimental groups,231.17 m L/g VS and 194.67 m L/g VS,respectively.Under the experimental conditions set in this paper,the optimal co-digestion feeds were: digestion substrates were ROW and RC,the mass ratio of VS is 1:1,the feed TS content was 12%,and the methane production was 339.59 m L/g VS.(4)According to the experimental conditions optimized for the anaerobic co-fermentation experiment,it was expanded to a pilot scale of 1 m~3 in equal proportion to verify its digestion effect.The pilot test was carried out for 36 d,methane content was stable at around 70%,and the cumulative methane production reached 464.46 m L/g VS,an increase of 36.77% compared to the laboratory test.The microbial community structure analysis showed that the microbial growth environment of AD pilot was well,and Methanosarcina and Firmicutes were the absolute dominant flora of archaea and bacteria,respectively.The pilot test of high-concentration anaerobic co-digestion of ROW has achieved more than expected results,provided technical support for the ROW biogas plant.