Study On The Effect Of Biochar Addition On Anaerobic Digestion Of Food Waste With Different Component Proportions

It is of great significance to explore the role of biochar in the anaerobic digestion of kitchen waste and expand the theoretical basis for the application of biochar in the anaerobic digestion of kitchen waste to investigate the influence of the addition amount of biochar on the anaerobic digestion of kitchen waste.In this study,three types of substrates including carbohydrates,proteins and lipids were used as the main sources of kitchen waste,and a comprehensive experimental design was conducted on two factors of biochar concentration and component ratio.Five additions of biochar（0,2.5g,5g,7.5g and 10g）and five carbohydrate to protein ratios（CA/CP）（1,2.5,4,5.5 and 7）were set,respectively,to study the gas production characteristics,system steady-state characteristics and organic component degradation characteristics of the anaerobic fermentation system of kitchen waste with different component ratios under different addition amounts of biochar.The correlation among the characteristic parameters was expounded,and the influence characteristics of biochar addition amount on the anaerobic fermentation of kitchen waste with different component proportions were clarified.The main conclusions of this study are as follows:（1）In the anaerobic fermentation system of kitchen waste with different proportions of organic components,gas production was significantly higher than that of other organic components when CA/CP was 1,2.5 and 4;When CA/CP was 1,the cumulative gas production of the fermentation system supplemented with 5g biochar was significantly higher than that without biochar（p<0.05）.When CA/CP was 4,the cumulative gas production of fermentation systems supplemented with 5,7.5 and 10g of biochar was significantly higher than that without biochar（p<0.01）,and the promotion effect was increased with the increase of biochar addition.In anaerobic fermentation systems with CA/CP values of 5.5 and 7,there was no significant effect of biochar addition.（2）Biochar addition had a significant effect on the changes of VS in the anaerobic fermentation system of restaurant kitchen waste,and the changes of VS were positively correlated with CA and CP in components（P<0.05）,but had no significant relationship with EE（P>0.05）.In general,different biochar supplemental levels had no significant direct effect on the three organic components in the anaerobic fermentation system of restaurant kitchen waste,but significantly affected the VS content,which was closely related to soluble carbohydrate content and soluble protein content,and had a significant negative correlation with EE.（3）There was a significant positive correlation between daily gas consumption and VFA（R²=0.168）in anaerobic fermentation system of kitchen waste with different proportion of organic components（P<0.01）.CH₄ yield was positively correlated with p H（R²=0.208）and VFA（R²=0.288）（P<0.01）.The changes of VFA in anaerobic fermentation system of kitchen waste with different proportion of organic components were significantly correlated with the degradation of each organic component,and had extremely significant positive correlation with TS（R²=0.304）and VS（R²=0.391）respectively（P<0.01）.There was significant negative correlation with CA（R²=-0.209）and CP（R²=-0.215）（P<0.01）,and significant positive correlation with component EE（R²=0.195）（P<0.01）.（4）The results of principal component analysis showed that the key factors affecting the anaerobic fermentation effect of kitchen waste with different proportions of organic components were gas production and solid content of anaerobic fermentation system,steady-state of reaction system and changes of organic components.The difference contribution rates of the three components were 30.764%,20.741%and 15.665%,respectively.The first principal component is the gas production and solids content affecting the anaerobic fermentation system,including daily gas production,CO2 production,TS concentration and VS concentration.The factors in the second principal component are mainly related to the steady-state of the reaction system,such as p H value and CH₄ production.The main influencing factor of the third principal component is the change of organic component,including fat content,protein content,and the change of AN concentration.