Life Cycle Assessment of Anaerobic Digestion of Food Waste:Taking Loudi City in Hunan Province as an Example
The food waste disposal process in Loudi City,Hunan Province,was selected as the research object,based on the life cycle assessment method,to analyze the impacts of each link of the disposal process on the environment and energy,to analyze the contribution of each functional unit to the environmental impacts,and to combine with the economic analysis to put forward optimization schemes.The results show that the food waste disposal process has a certain degree of negative impact on environmental acidification potential,human toxicity and aquatic ecotoxicity,eutrophication,and terrestrial ecotoxicity,mainly due to the negative effects of the sewage purification stage.The consumption of abiotic resources in the disposal process mainly stems from the alkaline substances used in the sewage purification process and fossil energy consumption in the transportation and transshipment process.The negative environmental impacts can be offset to some extent by the revenues generated by the biogas utilization process.Compared with the digestate incineration process,the digestate composting process reduces carbon emissions by 54%and other emissions by 76%while adding 11 827 t of organic fertilizer,with obvious environmental and by-product advantages.As shown in the economic analysis,the environmental and financial benefits of the food waste disposal process can be improved as much as possible by reducing energy consumption,increasing the biogas production rate,and recovering the by-products such as crude oil and digestate.