| With the acceleration of urbanization,polyester materials have become an indispensable part of life.Polyester bottles made of polyester materials are widely used in food,beverage,and daily cosmetics industries because of their light weight,good barrier properties,resistance to breakage,corrosion resistance,low cost,and high safety.At present,the social production of polyester bottles in China has exceeded 5 million tons per year,causing tremendous pressure on the environment.Therefore,due to the huge recoverable potential of waste polyester bottles,recycling and reusing polyester bottles have become an important direction for countries in the world to pursue the utilization of solid waste resources.This paper took waste polyester recycling process as the research object,analyzed its impact on environment,economy and society through life cycle assessment theory and sought countermeasures to alleviate environmental and economic pressure and reduce social impact.It has important strategic and practical significance for the healthy and rapid development of waste polyester recycling industry.Life cycle assessment(LCA),life cycle cost(LCC),and social life cycle(SLCA)were applied to study the environmental load,economic cost and social impact within the system boundary of "gate-gate".The key processes restricting the development were diagnosed and identified respectively.The sensitivity coefficient method was introduced to conduct sensitivity analysis on key processes of environment,economy and society,and to sort key processes by means of quantitative analysis.It is a useful complement to traditional LCA sensitivity analysis.The results showed that the polyester recycling process had a large environmental impact on global warming,mineral resource scarcity,human carcinogenic toxicity,water consumption and terrestrial ecotoxicity.Organic use was the link that contributes the most to economic costs,accounting for 65.9%of the total cost;the human health category accounted for a slightly larger proportion of social impact,reaching 45.8%,followed by the ecosystem by 45.3%;and the social impact of resource depletion was the smallest,reaching 9.0%.For environmental load,electricity generation,direct exhaust emission and transportation were most sensitive.The sensitivity coefficients were 6.19,3.06 and 3.00 respectively.For economic costs,the sensitivity coefficient of organic use was the largest,which was 1.033.The sensitivity coefficients of wastewater treatment and tap water use were the smallest,which were both 1.001.For social impact,the sensitivity coefficients of the six key processes were all great,which were all sensitive.According to the principle of synergy,the paper realized the three-coupled integration evaluation of ELCA,LCC and SLCA.The order degree of the system represented by the coordination effect function was used to express the environmental,economic and social integration effects of each key process,and the optimization of key processes is obtained.The sequence is organic use>electricity production>direct exhaust emission>transportation>wastewater treatment>coal mining.Based on the identification of key processes,the concept of traceability and the theory of circular economy "Reduce-Reuse-Recycle"(3R)were introduced.According to the position of the key process to be optimized in the waste polyester recycling process system,the optimization suggestions for source reduction,process reuse and waste resource recycling were separately proposed.Environmental pressure,economic costs and social impact were reduced obviously by improving the production process,introducing negative pressure dyeing technology to reduce the consumption of dyes,using clean energy sources such as solar energy to improve the electricity structure,updating the exhaust gas treatment equipment of the plant,and using the equipment with good filtering and high cleanliness to treat the exhaust gas,etc.It also provided useful reference for the improvement of the sustainability level in the polyester industry. |
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