Optimization Of Two-phase Anaerobic Fermentation Process For Kitchen Waste

Kitchen waste is an important part of municipal solid waste,which has the characteristics of high moisture content and high organic matter content,so it is considered to be a good substrate for anaerobic fermentation.Anaerobic fermentation of kitchen waste can produce hydrogen,methane,volatile fatty acids and other energy,and its reduction,harmless and resource treatment has attracted more and more attention.During the operation of the kitchen waste treatment project,the actual reduction and biogas production are also affected by process conditions,equipment,season and other factors.In this paper,a two-phase anaerobic fermentation process of leaching hydrolysis-anaerobic digestion is proposed and optimized,so that both leaching hydrolysis and anaerobic digestion can be reacted under suitable environmental conditions,so as to improve the overall process performance.The main contents of this paper are as follows:1.In this study,using Hangzhou kitchen waste as the substrate,three different spray solutions of hydrolysate,biogas slurry and biogas liquid+hydrolysate(1:1)were selected to carry out spray hydrolysis under the same other process conditions.to explore more biological hydrolytic spray solutions.The results showed that compared with biogas slurry,the hydrolysate and the mixture of biogas slurry and hydrolysate had no obvious promoting effect on the leaching and hydrolysis of kitchen waste.Considering that the reflux of hydrolysate will increase the difficulty of hydrolytic slurry treatment,biogas slurry is the most suitable biological hydrolytic leachate.2.Biogas slurry was selected as spray solution for biological hydrolysis of kitchen waste,and the effect of different spray ratio on biological hydrolysis was investigated.The results show that the higher spray ratio is beneficial to maintain the pH in the reactor in a suitable range,and the biological hydrolysis performance and the efficiency of producing volatile fatty acids are higher.Considering the operation cost in the actual project,the spray ratio of 1.6L/kg can be selected.3.Under suitable spraying conditions,the effect of temperature on the biohydrolysis of kitchen waste was investigated.The results showed that the suitable temperature for biological hydrolysis of kitchen waste was between 35?and 40?.4.Based on the experimental results of optimization of hydrolysis process conditions,the biological hydrolysis reactor and pipeline were insulated in the Tianziling kitchen waste treatment project in Hangzhou,so that the hydrolysis reaction temperature was 35?,the reflux ratio of biogas liquid was strengthened,and the spray ratio of biogas liquid was 1.6L/kg.Other process conditions are as follows:the residence time of the material in the hydrolysis reactor is 3d,the temperature of the material in the anaerobic fermentor is 35?,the solid content is about 4%?6%,the residence time is about 12d,and the reaction pH is 6.87.8.The final methane gas production rate is 42.97 m~3percussion t,which is 5.1%higher than that before process optimization,which increases the income of the Tianziling kitchen waste treatment project.5.The experiment of shortening the leaching retention time of the actual engineering process was carried out.under the condition that the spray ratio was unchanged,the decrease of substrate residence time had a great influence on the degradation rate of organic matter and had little effect on the wet weight reduction rate.It can be considered that in the future kitchen waste treatment project,the residence time of the material in the hydrolysis reactor can be shortened from 5 days to 3.09 days,which can improve the utilization rate of the biological hydrolysis reactor while ensuring the degradation effect of kitchen waste and the output of biogas.greatly reduce the cost of equipment.