The Research Of Plastics Metabolic Process Based On Material Flow Analysis In China

Over the past decade,the demand in China of plastics has grown rapidly.The increase of plastic’s production and consumption has caused a series of environmental problems.On the one hand,plastics are petrochemical products,and their extensive production and use have increased the consumption of petrochemical resources.On the other hand,plastic is difficult to decompose in the natural environment,not only occupying space resources,but also causing serious pollution to the environment,Based on the material flow analysis,this paper studied the dynamic evolution of plastic resources and established the waste plastic emission inventory in China.At the same time,scenario analysis was used to simulate the metabolic status of plastic resources in the future,and the waste plastic emission inventory was predicted under three different recycling situations in the futureIn the current situation analysis,a material flow analysis model of plastic resources in China was established to calculate the critical flows and stocks of the metabolism of plastic materials,and analyze the key nodes and driving forces.The results showed that from 1949 to 2018,the cumulative consumption of plastics in China was 1797.9 Mt,and the cumulative output of waste plastics was 1168.2 Mt.In 2018,the in-use stock of plastics in China was 446.6 Mt.The development of plastic industry is rapid,and the metabolism of plastic resources is huge.Of the waste plastics,20.0%were recycled,15.2%were incinerated,40.3%were into landfills and 24.5%were directly into the environment without treatment.Waste plastics is the key point of resource loss.The recycling material of waste plastics is prior and the waste plastics difficult to recycle is as much as possible to recycle energy.Reduce landfilling and discarding waste plastics to effectively promote the comprehensive utilization of plastic resourcesIn the current waste plastics emission inventory,the amount of macroplastic into the environment is 66.0 Mt and the amount of microplastic into the environment is 460.0 kt.Macroplastics in the ocean are mainly foam devices and nets used in aquaculture and fishing,while microplastics are mainly plastic beads in personal care products and fibers in the laundry process.Macroplastics in the ocean are related to the improper management and control of wastes generated by maritime activities;Macroplastics on the land are mainly related to the insufficient level of plastic waste collection and treatment.The microplastics in the ocean are mainly the wear and weathering during the use of plastic products;The microplastics on the land are related to emissions from the metabolic process of plasticsIn the scenario analysis,the demand for plastics in the social and economic system was analyzed based on the model driven by the in-use stock.According to the different stages of government planning,three different recycling scenarios are set up.The in-use stock in 2050 is 1029.1 Mt,which is only 2.3 times of that in 2018.From 2019 to 2050,the accumulative plastic input and output of socio-economic system are 4807.7 Mt and 4225.1 Mt respectively.The development of plastics industry has started to maintain a stable,plastic resources metabolism scale is also gradually controlled.Under the three scenarios of waste plastics treatment and disposal in 2050,the accumulative recycling of waste plastic was 6.0,6.9 and 7.8 times of that in 2018,and the accumulative discarding of waste plastic was only 1.8,1.6 and 1.4 times of that in 2018,respectively.The biogeochemical behavior and ecological risks of waste plastics in the environment need to be further studied.It is important to reduce the environmental impact of plastics and waste plastics by giving priority to the material recovery of waste plastics,supplemented by energy recovery,and reducing the landfill of waste plasticsIn terms of future waste plastics emission inventory,in three different scenarios,the amount of macroplastics into the environment is 68.0 Mt,50.0 Mt,48.0 Mt respectively,and the amount of microplastics into the environment is 544.0 kt,528.0 kt,532.0 kt respectively.The largest proportion of macroplastics in the ocean is still PS,and the largest proportion of microplastics in the ocean is still PET.The amount of macroplastic and microplastic in the environment decrease.Therefore,the amount of waste plastics entering the environment depends largely on the level of waste management and disposal.We will strengthen infrastructure for the disposal of household waste,strengthen relevant legislation and control,and raise the level of garbage collection and treatment.