Study On Co-production Of Biogas And Fuel Oil For Kitchen Waste

With the rapid development of the economy of China,the continuous expansion of the scale of urbanization and the prosperity of the catering industry,the emissions of table and kitchen waste were increasing year by year and the proportion of table and kitchen waste in the total daily waste in the city was also increasing.If effective treatment of these kitchen waste was causing serious harm to the environment.Kitchen waste was made up of table leftovers,the main ingredients were flour and rice,vegetables,animal and vegetable oil,meat,bones and so on.In view of the characteristics of kitchen waste such as high water content,high oil and salt content,it was easy to rot,deteriorate and to be decomposed by microorganisms,anaerobic fermentation could effectively deal with kitchen waste and generate clean energy methane at the same time.In this paper,firstly the effects of fermentation temperature,fermentation concentration,oil and salt on the biogas production by fermentation of kitchen waste were investigated.Secondly,the effect of organic load and fermentation temperature on the biogas production by anaerobic fermentation of kitchen waste was investigated by semi-continuous feeding method.Finally,on the basis of the previous study in this laboratory,the experimental study on the preparation of fuel oil by catalytic cracking of waste oil separated from kitchen waste under the condition of adding three kinds of si-al ratio catalysts was carried out.The conclusions of this paper are as follows:?1?Fermentation temperature,fermentation concentration,oil and salt all have certain influence on biogas produced by anaerobic fermentation of kitchen waste.The results show that the anaerobic fermentation of kitchen waste is the best at 45?and the fermentation concentration is 8%.The cumulative gas producti on reaches 30L,the cumulative methane content is 16.5L,and the TS gas production rate is0.38L·?gTS?^-1.The gas production rate of VS is 0.58 L·?gVS?^-1,the degradation rate of TS was 62.38%,the degradation rate of VS is 69.20%,and the gas yield of the tank is 0.64 m³·m^-3·d^-1.The study on the effect of oil on biogas production shows that the addition of oil can promote biogas fermentation in a certain range.When the amount of oil is 4g·L^-1,the biogas production will be the best.The cumulative gas pr oduction is 11.13L,the cumulative methane production is 5.85L,the gas production rate of TS is0.22L.?gTS?^-1,the gas production rate of VS is 0.36L·?gVS?^-1,the degradation rate of TS was 40.5%,and the degradation rate of VS is76.3%.The effect of salt on the biogas production performance shows that when the salt content is 6g·L^-1,the biogas production will be the best,the cumulative gas production is 10.27L,the cumulative methane production is6.43L,and the TS gas production rate is 0.22L·?gTS?^-1,VS gas production rate is 0.35 L·?gVS?^-1,TS degradation rate is 29.22%,and VS degradation rate is 47.31%.Salt content in the range of 2¹0g·L^-1can promote other parameters besides inhibiting the degradation rate of TS and VS.?2?In the semi-continuous fermentation of kitchen waste,the effects of organic load and temperature on biogas production were investigated.The results shows that the daily gas production is increasing gradually with the increase of organic load.The maximum daily gas productio n is achieving at the organic load of 3.25 gVS·L^-1·d^-1.The average TS gas production rate is 1.32L·?gTS?^-1,the average VS gas production rate is1.41L·?gVS?^-1,and volumetric biogas yield under optimum organic load conditions is 4.58 m³·m^-3·d^-1.With the increase of organic load,the stability of fermentation system has changed,and the pH value and methane content in biogas has decreased gradually.?3?In the experimental study on the preparation of fuel oil from food and kitchen waste grease,under the condition of 5.25h^-1 mass air speed,by comparing the influences of different temperatures on the yield and the acid value of fuel oil under the conditions of adding ZSM-5?sial-al ratio25:1?,ZSM-5?sial-al ratio 38:1?and ZSM-5?sial-al ratio 50:1?catalysts,the better catalytic cracking process conditions were obtained as follows:Add ZSM-5?si/al ratio 25:1?catalysts,catalytic cracking temperature is470?,the yield is 68%,acid value of 3 mgkOH·g^-1.GC-MS analysis of fractionated fuel oil under better FCC co nditions show that the fuel oil composition is basically the product of C5-C9,with a large proportion of homologues of benzene and benzene,and a maximum of 38.13%of toluene.Secondly,nitrogen and alkanes,as well as a small number of alcohols and olefin compounds,account for a large proportion.This indicates that aromatics isomerization takes place mainly in catalytic cracking reaction.