RCR新 ：美国废塑料管理的环境和经济影响

塑料一直是人们生产和生活不可或缺的材料，然而废塑料的处置问题却一直未能得到很好的解决，不当的处置方式会对环境产生极大的负面影响。许多塑料资源在短暂的一次使用之后就进入废弃处置环节，也是对资源的低效率利用。

2018年中国出台垃圾进口禁令，美国无法将产生的废塑料转移到中国回收，而美国国内的回收市场尚不完善，因此废塑料的收集和处置成为亟待解决的问题。但同时这也是美国废塑料管理市场改进的一个契机，能够为美国回收基础设施建设和废塑料市场的创建提供机会。这也对美国提出了三个关键问题：（1）废塑料管理系统在目前的收集率下是如何运作的；（2）将收集率提高到100%，将会对美国产生什么影响，100%的废塑料回收率对投资和基础设施的需求；（3）如何更好地管理所有废塑料。

1.探索了美国废塑料基于过程的综合处置方法；

2.低收集率是不经济的，不会减少温室气体排放；

3.需要改进能源回收、燃料回收和再循环过程；

4.只增加收集量不会带来预期的温室气体减排效果；

5.回收实践的设计需要最大限度的回收废弃物。

章摘要

图1 （a）2017年美国废塑料废物产生情况；（b）每种1-7树脂可用的塑料废物处理方案总结；（c）本研究中用于分析的复合处理方案；（d）本研究的分析边界

图2 （a）方案Major-DER（Majority Direct Energy Recovery）的质量流桑基图，（b）当前（2017年）收集量（8.4%）下复合处理方案Major-DER对全系统温室气体净减排量?0.88 TgCO2（左）和全系统净收入?0.66亿美元（右）的贡献

图3 BAU（Bussiness as usual）情景下Major-DER、Major-FR（Majority Fuel Recovery）和Major-REC（Majority Recycling）的温室气体净减排（上图）和净收入（下图）随收集率的变化

图4 收集量函数的经济和环境权衡（圆圈大小随收集量变化）

表1 本研究单位温室气体排放因子与 献中排放因子的比较

Abstract

With only 8.4% of end-of-life plastics collected for recycling in 2017, management of postconsumer plastic waste in the U.S. has raised significant concerns. We present an integrated approach to assess the environmental benefits and economic implications of plastic waste management by interfacing collection and sorting with process-based treatment models for energy recovery, fuel recovery and mechanical recycling. Three composite treatment scenarios are analyzed under various techno-economic contexts to understand the key drivers of greenhouse gas (GHG) emissions/savings and economic viability. At current collection volumes, both net GHG savings and net annual revenue are unfavorable. Scaling collection rates from the current level to a hypothetical 100% exposes inefficiencies beyond the collection bottleneck and results in net GHG emissions. We find that a business-as-usual increase in collection volume alone would be insufficient to offset GHG emissions and is uneconomical. We quantify the potential found in improving waste-to-energy efficiencies, developing high-yield plastics-to-fuel pathways and incorporating design for recycling considerations. From an economic standpoint, external market factors such as sale price of electricity, fuels and virgin resins are critical to financial viability of treatment processes. This analysis also allows us to appropriately assess the magnitude of investment and type of policy efforts needed to address the problem. To effectively collect and treat 100% of all U.S. postconsumer plastic waste, an upfront investment of 17–21 Billion USD is estimated. This approach underscores the importance of a systems perspective that acknowledges the complexity of the postconsumer plastic waste stream to sustainably achieve plastic waste management objectives.

胡蕾，南昌大学，研究方向：循环经济。