Klotz Magdalena, Oberschelp Christopher, Salah Cecilia, Subal Luc, Hellweg Stefanie
Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Stefano-Franscini-Platz 5, 8093 Zurich, Switzerland.
Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Stefano-Franscini-Platz 5, 8093 Zurich, Switzerland; National Centre of Competence in Research (NCCR) Catalysis, ETH Zurich, Leopold-Ružička-Weg 4, 8093 Zurich, Switzerland.
Sci Total Environ. 2024 Jan 1;906:167586. doi: 10.1016/j.scitotenv.2023.167586. Epub 2023 Oct 5.
Chemical and solvent-based recycling of plastic waste may help overcome some of the challenges faced by predominantly applied mechanical recycling techniques. This study quantifies the environmental impacts of chemical and solvent-based recycling as a function of varying process parameters and product composition using life cycle assessment. Furthermore, potential benefits and impacts on a system level are determined. To that end, a high-resolution material flow analysis is conducted for the reference system of Switzerland, covering all main plastic types and applications. In a scenario for the year 2040, we employ environmentally beneficial mechanical recycling where possible and convey suitable remaining waste streams to chemical or solvent-based recycling processes. Applying chemical or solvent-based recycling as a complement to maximum mechanical recycling, instead of thermal treatment with energy recovery, may achieve a reduction in the climate change impact of the system ranging from less than 10 % to almost 40 %. For achieving high environmental benefits, proper process choice and configuration are crucial. Dissolution or depolymerization provide higher benefits relative to other chemical recycling processes, but can only treat certain waste streams and require prior sorting into plastic types. Pyrolysis and gasification appeared to only have the ability to achieve substantial benefits over incineration if their output products can substitute high-impact chemicals and provided that efficient heat transfer and recovery is warranted when implemented on a large scale. As industrial-scale plants for chemical or solvent-based plastic recycling are still lacking, the upscaling potential and the environmental benefits achievable in practice are highly uncertain today.
基于化学和溶剂的塑料废物回收利用可能有助于克服主要应用的机械回收技术所面临的一些挑战。本研究使用生命周期评估方法，将基于化学和溶剂的回收利用对环境的影响量化为不同工艺参数和产品成分的函数。此外，还确定了系统层面的潜在益处和影响。为此，针对瑞士的参考系统进行了高分辨率的物质流分析，涵盖了所有主要的塑料类型和应用。在2040年的一个情景中，我们尽可能采用对环境有益的机械回收利用，并将合适的剩余废物流输送到基于化学或溶剂的回收工艺中。将基于化学或溶剂的回收利用作为最大程度机械回收利用的补充，而不是进行有能量回收的热处理，可能会使系统的气候变化影响降低10%以下至近40%。为了实现高环境效益，正确选择工艺和配置至关重要。相对于其他化学回收工艺，溶解或解聚能带来更高的效益，但只能处理某些废物流，并且需要预先按塑料类型进行分类。热解和气化似乎只有在其产出产品能够替代高影响化学品，并且在大规模实施时保证有效传热和回收的情况下，才有能力比焚烧实现更大的效益。由于目前仍缺乏用于基于化学或溶剂的塑料回收的工业规模工厂，如今其扩大规模的潜力以及在实际中可实现的环境效益高度不确定。
