Sustainable Industrial Systems, Department of Chemical Engineering, The University of Manchester, Manchester, UK.
Sustainable Industrial Systems, Department of Chemical Engineering, The University of Manchester, Manchester, UK.
Waste Manag. 2024 Apr 30;179:55-65. doi: 10.1016/j.wasman.2024.03.005. Epub 2024 Mar 9.
Biodiesel production produces significant quantities of impure crude glycerol as a by-product. Recent increases in the global biodiesel production have led to a surplus of crude glycerol, rendering it a waste. As a result, different methods for its valorisation are currently being investigated. This paper assesses the life cycle environmental impacts of an emerging technology for purification of crude glycerol - a multi-step physico-chemical treatment - in comparison to incineration with energy recovery commonly used for its disposal. For the former, three different acids (HPO, HSO and HCl) are considered for the acidification step in the purification process. The results suggest that the HSO-based treatment is the best option with 17 net-negative impacts out of the 18 categories considered; this is due to system credits for the production of purified glycerol, heat and potassium salts. In comparison to incineration with energy recovery, the HSO-based process has lower savings for the climate change impact (-311 versus -504 kg CO eq./t crude glycerol) but it performs better in ten other categories. Sensitivity analyses suggest that that the impacts of the physico-chemical treatment are highly dependent on crude glycerol composition, allocation of burdens to crude glycerol and credits for glycerol production. For example, treating crude glycerol with lower glycerol content would increase all impacts except climate change and fossil depletion due to the higher consumption of chemicals and lower production of purified glycerol. Considering crude glycerol as a useful product rather than waste and allocating to it burdens from biodiesel production would increase most impacts significantly, including climate change (22-40 %), while fossil depletion, freshwater and marine eutrophication would become net-positive. The findings of this research will be of interest to the biodiesel industry and other industrial sectors that generate crude glycerol as a by-product.
生物柴油生产会产生大量不纯的粗甘油，这是一种副产物。最近全球生物柴油产量的增加导致了粗甘油的过剩，使其成为一种废物。因此，目前正在研究不同的方法来提高其附加值。本文评估了一种新兴的粗甘油净化技术的生命周期环境影响，该技术采用多步物理化学处理方法，与通常用于处理粗甘油的焚烧和能量回收方法进行了比较。对于前者，在净化过程的酸化步骤中考虑了三种不同的酸（HPO、HSO 和 HCl）。结果表明，基于 HSO 的处理是最佳选择，在所考虑的 18 个类别中有 17 个具有净负面影响；这是由于生产纯化甘油、热量和钾盐的系统信用。与焚烧和能量回收相比，基于 HSO 的工艺在气候变化影响方面的节约较少（-311 与-504 kg CO eq./t 粗甘油），但在其他十个类别中表现更好。敏感性分析表明，物理化学处理的影响高度依赖于粗甘油的组成、将负担分配给粗甘油以及甘油生产的信用。例如，用含甘油量较低的粗甘油进行处理，由于化学物质消耗增加和纯化甘油产量降低，除气候变化和化石枯竭外，所有影响都会增加。将粗甘油视为有用的产品而不是废物，并将生物柴油生产的负担分配给它，会显著增加大多数影响，包括气候变化（22-40%），而化石枯竭、淡水和海洋富营养化将变为净正影响。这项研究的结果将引起生物柴油行业和其他产生粗甘油作为副产物的工业部门的兴趣。
