Full-chain carbon emission comparison analysis of wet and dry anaerobic digestion of kitchen waste
In the present,anaerobic digestion is the most commonly used technology for kitchen waste treatment in China,and can be divided into two categories:dry and wet.In this study,based on the"pre-treatment slurry+wet anaerobic digestion"and"pre-treatment trash removal+dry anaerobic digestion",the carbon emissions of the whole chain of dry and wet kitchen waste anaerobic digestion processes are analysed respectively,and the carbon emission sources and carbon emission boundaries of anaerobic digestion are determined.The net carbon emissions from anaerobic digestion were determined by determining the carbon emission sources and carbon emission boundaries of anaerobic digestion,measuring the direct carbon emissions,indirect carbon emissions and avoidable carbon emissions,and finally combining these three types of emissions.It was found that the dry anaerobic digestion process with digestate reflux had the highest chain carbon emission reduction of-84.43 kg/t.The main source of direct carbon emissions from the dry process was impurity incineration,while the main source of direct carbon emissions from the wet process was effluent treatment and impurity incineration;The main source of indirect carbon emissions from both processes was electricity consumption.The carbon reduction effect from biogas generation and waste heat utilisation is the largest carbon reduction sub-component in the whole process of anaerobic digestion of food waste,and using biogas yield as the output target can produce a better carbon reduction effect than using fertiliser as the target.This study provides a reference for the use of dry or wet anaerobic digestion of food waste and carbon reduction management options.
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