School of Water, Energy and Environment, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK.
School of Water, Energy and Environment, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK.
Waste Manag. 2018 Jun;76:55-67. doi: 10.1016/j.wasman.2018.03.043. Epub 2018 Apr 2.
In Europe over 5.25 billion tonnes of waste has been landfilled between 1995 and 2015. Among this large amount of waste, plastic represents typically 5-25 wt% which is significant and has the potential to be recycled and reintroduced into the circular economy. To date there is still however little information available of the opportunities and challenges in recovering plastics from landfill sites. In this review, the impacts of landfill chemistry on the degradation and/or contamination of excavated plastic waste are analysed. The feasibility of using excavated plastic waste as feedstock for upcycling to valuable chemicals or liquid fuels through thermochemical conversion is also critically discussed. The limited degradation that is experienced by many plastics in landfills (>20 years) which guarantee that large amount is still available is largely due to thermooxidative degradation and the anaerobic conditions. However, excavated plastic waste cannot be conventionally recycled due to high level of ash, impurities and heavy metals. Recent studies demonstrated that pyrolysis offers a cost effective alternative option to conventional recycling. The produced pyrolysis oil is expected to have similar characteristics to petroleum diesel oil. The production of valuable product from excavated plastic waste will also increase the feasibility of enhanced landfill mining projects. However, further studies are needed to investigate the uncertainties about the contamination level and degradation of excavated plastic waste and address their viability for being processed through pyrolysis.
在 1995 年至 2015 年期间，欧洲有超过 52.5 亿吨废物被填埋。在这大量的废物中，塑料通常占 5-25wt%，这是一个显著的比例，具有回收和再引入循环经济的潜力。然而，迄今为止，关于从垃圾填埋场回收塑料的机会和挑战的信息仍然很少。在这篇综述中，分析了垃圾填埋场化学物质对挖掘出的塑料废物降解和/或污染的影响。还批判性地讨论了通过热化学转化将挖掘出的塑料废物作为原料升级为有价值的化学品或液体燃料的可行性。许多塑料在垃圾填埋场中经历的有限降解（>20 年）保证了大量的塑料仍然可用，这主要是由于热氧化降解和厌氧条件。然而，由于灰分、杂质和重金属含量高，挖掘出的塑料废物不能进行常规回收。最近的研究表明，热解为传统回收提供了一种具有成本效益的替代选择。所生产的热解油预计具有与石油柴油相似的特性。从挖掘出的塑料废物中生产有价值的产品也将提高强化垃圾填埋场开采项目的可行性。然而，需要进一步研究来调查挖掘出的塑料废物的污染水平和降解的不确定性，并解决其通过热解进行处理的可行性。
