城市有机废弃物处理处置过程全生命周期评价——以国内某设计工程为例

Life cycle assessment of urban organic waste treatment and disposal process:a case study of a design project in China

以某城市有机废弃物处理处置设计工程为例,采用eFootprint系统建立模型,对其进行全生命周期评价。通过对5种环境影响评价指标,即全球变暖潜能(Global Warming Potential,GWP)、初级能源消耗(Primary energy demand,PED)、酸化(Acidification,AP)、富营养化(Eutrophication,EP)、光化学臭氧合成(Photochemical ozone formation,POFP)的分析,得出当功能单位为处理1t城市有机废弃物时,5个指标值分别为123.34kg CO2eq、1112.06MJ、0.0725kg SO2eq、-0.0735kg PO43-eq、0.0806kg NMVOC eq。此外,还对城市有机废弃物处理处置过程进行分析,通过对混合调质、高温热水解、厌氧消化、沼渣脱水、太阳能干化、沼气利用这几个环节的指标研究,发现脱水环节由于电耗较高,因此对于能源消耗及环境影响方面的负效应最大,其消耗/排放指标超过了其他所有环节的总和。除此之外,沼气利用及肥料替代对于LCA各指标的影响巨大,表明处理产物的得当处置将带来巨大的环境效益,使得废弃物管理系统在迈向资源化及能源化利用的同时,减少了全过程能源使用及环境排放。

Taking the design project of organic waste treatment and disposal in a city as an example,the eFootprint system was used to establish the model and evaluate the whole life cycle of the project.Through the analysis of five environmental impact assessment indicators,namely Global Warming Potential(GWP),Primary Energy Demand(PED),Acidification(AP),Eutrophication(EP),Photochemical Ozone Formation(POFP),it is concluded that the functional units are climate change(GWP),primary energy demand(PED),acidification(AP),eutrophication(EP),photochemical ozone formation(POFP).When treating 1 ton of municipal organic wastes,the five indicators were 123.34 kg CO2 eq,1112.06 MJ,0.0725 kg SO2 eq,-0.0735 kg PO43-eq and 0.0806 kg NMVOC eq,respectively.In addition,the process of treatment and disposal of municipal organic wastes is also analyzed.Through the study on the indexes of mixing conditioning,high temperature hot water hydrolysis,anaerobic digestion,dewatering of biogas residue,solar drying and biogas utilization,it is found that the dewatering link has negative effects on energy consumption and environmental impact due to its high power consumption.It should be the largest,and its consumption/emission index exceeds the sum of all other links.In addition,biogas utilization and fertilizer substitution have a great impact on LCA indicators,indicating that proper disposal of the treated products will bring huge environmental benefits,making waste management system towards resource and energy utilization,while reducing the whole process of energy use and environmental emissions.