Study On The Effect Of Segmented Treatment On Anaerobic Digestion Of Food Waste

With the improvement of people’s living standards,my country will produce a large amount of food waste every year.Improper handling will cause certain harm to the environment.Proper handling will turn waste into treasure.Anaerobic digestion technology can realize the harmlessness and resource utilization of food waste by converting organic waste into methane.Based on this,this article takes food waste as the research object,adopts a two-stage anaerobic digestion process for methane production,and studys the fermentation characteristics of the two stages of hydrolysis and acidification of kitchen waste at high temperature of 50℃。Explore the influence of different exogenous bacteria groups on acidification,analyze the changes of pH,VFA,sCOD,TS,VS,gas production,methane content,methane yield and other parameters during the fermentation process,and make efficient resource utilization of food waste Provide scientific exploration.The main results are as follows:（1）The self-hydrolysis and acidification process of food waste took 5 days,and the pH of the system dropped rapidly to 4.97 on the first day,then increased slightly to 5.15 and then continued to drop to 4.69.At the end of acidification,the concentration of VFA increased by25.1%compared with the feed solution.Acetic acid was the main acidification product,with a concentration of 3.11 mg/mL,accounting for 97.49%of the total concentration of VFA.The increase in sCOD dissolution and the decrease in TS and VS content mainly occurred before the reaction 1-2 d.At the end of the reaction,the sCOD concentration reached 174.34 g/L,and the VFA/sCOD ratio was 0.018.In the digestion and gas production section,the accumulation of VFA did not significantly inhibit the reaction system.The system has been in an alkaline environment with a maximum pH of 8.65,which shows that the activated sludge flora has a high tolerance to alkalinity.The system gas production mainly occurs 10 days before the reaction.At the end of the reaction,the biogas production volume reaches 0.42L/g TS,the average methane production rate from 0-16 days reaches 315.47 mLCH₄/g VS,and the highest methane content is 67.49%.（2）Add bovine dung bacteria and cellulolytic bacteria to the kitchen waste for hydrolysis and acidification.At the end of the reaction,the VFA concentration will be 3.94mg/mL（add bovine dung bacteria）and 5.70 mg/mL（add cellulose decomposing bacteria Y033）,the main VFA components of the two systems are butyric acid,accounting for about 70%,followed by acetic acid.Compared with the feed solution,the VFA concentration increased by 65.39%（adding bovine dung bacteria）and 139.97%（adding cellulose decomposing bacteria Y033）.The addition of exogenous bacteria significantly improved the hydrolysis and acidification effect of food waste,especially the addition of fiber The system of decomposing flora.The cumulative biogas volume of the system with the addition of bovine dung bacteria in the digestion and gas production section is higher than that of the system with the addition of cellulose decomposing bacteria,which are 16.08L（adding bovine dung bacteria）and 15.85L（adding cellulose decomposing bacteria Y033）.0-16 d The methane yield of kitchen waste with the addition of bovine dung bacteria is 281.98 mlCH₄/g VS,and the methane yield of kitchen waste with the addition of cellulolytic bacteria is 322.08mlCH₄/g VS,and the kitchen with the addition of cellulosic bacteria can be found The methane production rate of garbage is obviously higher.At the end of digestion and gas production,the acetic acid and butyric acid systems added with bovine fecal bacteria and cellulolytic bacteria are consumed and reduced to 0.27 mg/mL,0.006 mg/mL,0.24 mg/mL,0.01mg/mL,respectively.However,the concentrations of propionic acid and valeric acid have been accumulating,especially the concentrations of propionic acid are as high as 1.88mg/mL（adding bovine dung bacteria）and 1.79mg/mL（adding cellulose decomposing bacteria Y033）.（3）After 16S＿rRNA amplification sequencing,it was found that the bacterial advantage bacteria at the initial stage of hydrolytic acidification reaction were Firmicutes,Proteobacteria,Cyanobacteria and Bexeroidota,and at the end of the reaction the dominant bacteria were Firmicutes and Proteobacteria;Methomobacter and Methanosarcina,but at the end of the reaction the dominant strains of the bacteria were Methanoculleus and Methanosarcina.At the beginning of the digestive gas-producing segment reaction,the bacterial advantage bacteria Firmicutes,Synergistota,Thermotogae,Bacteroidota,Halobacterota,and at the end of the reaction the dominant bacteria gate is Firmicutes,Thermotogae,Proteobacteria,Bacteroidota,Synergistota.The dominant genus of the genus Genus Methanoculleus and Methanosarcin.At the end of the reaction,the dominant germs were Methanoculleus,Methanosarcina,and Methanobacterium.（4）From RDA,it is found that environmental factors have the following effects on bacterial colonies:VFA has a greater impact on Defluviitoga,which is a positive pass.The effects of VFA,COD and TS（VS）on the dominant bacteria Bacillus are similar.When the system VFA concentration is high,Lactobacillus,Serratia,Leuconostoc and Pseudomonas are basically intolerant.