Sustainable Industrials Systems, School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M13 9PL, UK.
Sustainable Industrials Systems, School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M13 9PL, UK.
J Environ Manage. 2019 Apr 15;236:798-814. doi: 10.1016/j.jenvman.2019.02.001. Epub 2019 Feb 15.
Consumers are the leading producers of food waste (FW) in developed countries and the majority of household FW is still embedded in general waste where it is incinerated or landfilled. There is increasing awareness in the value of collecting FW as a separate waste stream for production of compost or recovery of energy through anaerobic digestion (AD). This study focuses on AD to evaluate the life cycle environmental sustainability of recovering energy and fertilisers from household FW in the UK. The analysis is carried out for two different functional units: i) treatment of 1 tonne of FW, which is compared to incineration and landfilling; and ii) generation of 1 MWh of electricity, which is compared to other electricity generation options. The former results in net negative greenhouse gas (GHG) emissions (-39 kg CO-eq./t) and primary energy demand (-2 GJ/t) due to the displacement of grid electricity and mineral fertilisers. AD has lower impacts than both incineration and landfilling across 15 of the 19 impacts. However, the application of digestate to land and the release of ammonia and nitrates lead to higher marine eutrophication (ME), terrestrial acidification (TA) and particulate matter formation (PMF). For the second functional unit, AD electricity emits 203 kg CO-eq./MWh, compared to 357 kg CO-eq./MWh for the UK grid mix. Compared to renewables, such as wind and solar, AD electricity has lower energy demand, toxicity potentials and metal depletion. However, it has higher global warming potential, ME, TA and PMF. At the UK level, treating 4.9 Mt of kerbside FW collected annually could provide 0.37% of the national electricity demand and save 190,000 t CO-eq./yr compared to the grid electricity. The digestate produced could displace 1% of industrial nitrogen fertilisers. Although small fractions of the national demands, they represent a valuable return from a largely unutilised waste stream and help towards implementation of a circular economy.
消费者是发达国家食物垃圾（FW）的主要产生者，而大部分家庭 FW 仍被嵌入到普通垃圾中，进行焚烧或填埋。人们越来越意识到收集 FW 作为一个单独的废物流的价值，以便通过厌氧消化（AD）生产堆肥或回收能源。本研究专注于 AD，以评估从英国家庭 FW 中回收能源和肥料的生命周期环境可持续性。该分析针对两个不同的功能单位进行：i）处理 1 吨 FW，与焚烧和填埋进行比较；ii）产生 1 兆瓦时的电力，与其他发电选项进行比较。前者由于替代电网电力和矿物肥料，导致净负温室气体（GHG）排放（-39kg CO-eq./t）和一次能源需求（-2GJ/t）。在 19 个影响因素中的 15 个方面，AD 的影响小于焚烧和填埋。然而，消化物施用到土地上以及氨和硝酸盐的释放会导致更高的海洋富营养化（ME）、陆地酸化（TA）和颗粒物形成（PMF）。对于第二个功能单位，AD 电力排放 203kg CO-eq./MWh，而英国电网组合电力排放 357kg CO-eq./MWh。与风能和太阳能等可再生能源相比，AD 电力的能源需求、毒性潜力和金属消耗较低。然而，它具有更高的全球变暖潜力、ME、TA 和 PMF。在英国，每年处理 490 万吨路边收集的 FW 可以提供全国电力需求的 0.37%，并与电网电力相比，每年节省 19 万吨 CO-eq.。所生产的消化物可以替代 1%的工业氮肥肥料。尽管只占全国需求的一小部分，但它们代表了从一个未充分利用的废物流中获得的宝贵回报，并有助于实现循环经济。
