Each year, millions of tons of plastics are produced for use in such applications as packaging, construction, and textiles. While plastic is undeniably useful and convenient, its environmental fate and transport have raised growing concerns about waste and pollution. However, the ease and low cost of producing virgin plastic have so far made conventional plastic recycling economically unattractive. Common contaminants in plastic waste and shortcomings of the recycling processes themselves typically mean that recycled plastic products are of relatively low quality in some cases. The high cost and high energy requirements of typical recycling operations also reduce their economic benefits. In recent years, the bio-upcycling of chemically treated plastic waste has emerged as a promising alternative to conventional plastic recycling. Unlike recycling, bio-upcycling uses relatively mild process conditions to economically transform pretreated plastic waste into value-added products. In this review, we first provide a précis of the general methodology and limits of conventional plastic recycling. Then, we review recent advances in hybrid chemical/biological upcycling methods for different plastics, including polyethylene terephthalate, polyurethane, polyamide, polycarbonate, polyethylene, polypropylene, polystyrene, and polyvinyl chloride. For each kind of plastic, we summarize both the pretreatment methods for making the plastic bio-available and the microbial chassis for degrading or converting the treated plastic waste to value-added products. We also discuss both the limitations of upcycling processes for major plastics and their potential for bio-upcycling.

中文翻译：

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化学和生物塑料串联升级再造的现状


每年生产数百万吨塑料，用于包装、建筑和纺织品等应用。虽然塑料无疑是有用和方便的，但它的环境命运和运输方式也引起了人们对废物和污染的日益担忧。然而，迄今为止，生产原生塑料的简便性和低成本使传统的塑料回收在经济上没有吸引力。塑料垃圾中的常见污染物和回收过程本身的缺陷通常意味着在某些情况下，回收塑料产品的质量相对较低。典型回收操作的高成本和高能源要求也降低了其经济效益。近年来，经过化学处理的塑料废弃物的生物升级回收已成为传统塑料回收的有前途的替代方案。与回收不同，生物升级回收使用相对温和的工艺条件，以经济的方式将预处理过的塑料废物转化为增值产品。在这篇综述中，我们首先提供了传统塑料回收的一般方法和限制的概要。然后，我们回顾了不同塑料的混合化学/生物升级回收方法的最新进展，包括聚对苯二甲酸乙二醇酯、聚氨酯、聚酰胺、聚碳酸酯、聚乙烯、聚丙烯、聚苯乙烯和聚氯乙烯。对于每种塑料，我们总结了使塑料具有生物利用性的预处理方法和用于将处理过的塑料废物降解或转化为增值产品的微生物底盘。我们还讨论了主要塑料升级回收工艺的局限性及其生物升级回收的潜力。