Study On Characteristics Of Mixed Anaerobic Fermentation Of Multiple Organic Wastes In Northern Farmers

Urban garbage classification has begun to implement,and how to deal with rural household garbage should also be put on the agenda.First of all,we should start planning from the dry and wet separation,and use anaerobic fermentation to harmless and resource utilization of rural organic wet garbage from the source,which is one of the most important links to achieve carbon peak and rural revitalization.However,due to the differences in food and organic waste production in rural areas between the north and the south,and the complex variety of organic waste components,it is necessary to investigate the typical villages and towns from the practical problems,and put forward the reasonable allocation scheme of raw materials for anaerobic fermentation according to the investigation.Therefore,taking the farmers in Hongguang Township,Bayan County,Harbin City,Heilongjiang Province as the research object,the main types and average output of organic waste of typical farmers in the north were obtained by questionnaire survey.Secondly,the composition of organic waste was analyzed,and corn straw was added for conditioning.Based on the idea of universal rotational combination design,the biogas production performance of kitchen waste,human feces and corn straw mixed with organic waste was studied.The response surface method and BP neural network were used for prediction and optimization.The raw material ratio group with the best biogas production performance was obtained through experimental verification.Finally,the process design of mixed anaerobic fermentation of organic waste produced by farmers was carried out,and the economy of the whole process was evaluated according to the experimental results and the actual investigation.The following results and conclusions are obtained:(1)Kitchen waste and human feces are the main components of rural organic domestic waste,accounting for about 75 per cent of the total.According to the survey,ki tchen waste and human feces produced by each household are significantly correlated with the population.The number of households is mainly concentrated in 3-4 people,accounting for about 62.3%of the total,which is basically in line with the composition of the three ordinary families.After analysis of variance by SPSS software,there was no significant difference between kitchen waste and human feces produced by 3-4 people(P>0.05).The average output of kitchen waste per person per day was about 561.42 g,and the output of human feces was about 673.71 g.Therefore,according to 3-4people per household,the daily output of kitchen waste was about 1.69-1.80 kg,and the output of human feces was about 2.02-2.16 kg.(2)Appropriate mixing ratio of raw materials can effectively improve the gas production rate of mixed anaerobic fermentation.The results showed that the fermentation p H of each experimental group was stable at 6.9-7.5,and the accumulation of volatile fatty acids did not appear.The methane production rate of TS was 95.38-302.80 m L/g.When the ratio of kitchen waste,human feces and corn straw was 23:41:10,the anaerobic fermentation effect was the best,and the cumulative methane amount was the highest.The methane production rate of VS and TS was 315.40 m L/g and 302.80 m L/g,and the degradation rates of cellulose,hemicellulose and lignin were 31.97%,43.66%and 3.36%,respectively.In addition,both the response surface method and BP neural network can well predict the methane production mo del(R~2 is close to 1).The optimal raw material TS ratio is 23:44:9,and the total solid concentration(TS)is 8%.When the methane content reaches 59.25%,the maximum biogas yield is 0.33 m~3/kg,and the prediction error values of the two are 0.0106 and 0.0090,respectively,which also indicates that the artificial neural network is more authoritative in exploring the nonlinear relationship variables.(3)A simple fermentation process package was designed based on the results of small-scale test,actual investigation and related technical requirements,which provided reference for subsequent engineering implementation.And through the calculation of each household with 3-4 population,farmers can save 1311.02 yuan per year,which means that the northern cold environment friendly treatment mode is more suitable for farmers to deal with multiple organic waste.