Civil and Infrastructure Engineering, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia.
Department of Civil Engineering, Monash University, Melbourne, VIC 3800, Australia.
Sci Total Environ. 2023 Jul 10;881:163488. doi: 10.1016/j.scitotenv.2023.163488. Epub 2023 Apr 15.
The study aims to conduct a comprehensive life cycle assessment (LCA) of mixed glass waste (MGW) recycling processes to quantify the environmental impacts of crushed glass as a partial substitute for virgin aggregate. Upstream washing, crushing, and sorting conducted at material recycling facilities (MRF) are the prime activities to assess whether reprocessed MGW in pavement construction is an alternate feasible solution. None of the previous studies explicitly account for the relative uncertainties and optimization of waste glass upstream processes from an environmental perspective. The study calculates environmental impacts using the LCA tool SimaPro considering design factors attributed to transportation, electricity consumption, use of chemicals, and water for reprocessing glass waste. Relative uncertainties of design variables and the national transition policy (2021-2030) from non-renewable to renewable energy sources have been validated by performing detailed Monte Carlo simulations. The correlation coefficients (r = 0.64, 0.58, and 0.49) of successive variables explain how the higher environmental gains of the glass recycling process are outweighed by diesel, energy consumption, and transportation distances. Compared to natural quarry sand, the recycled glass aggregate produced through crushing and recycling of its by-products reduces COeq emissions by 16.2 % and 46.7 %, respectively. The need for a washing line at the plant, in addition to crushing, results in a higher environmental impact over natural sand by 90.1 % and emphasizes the benefits of collecting waste glass through a separate bin, hence avoiding contamination. The result indicates that the benefit of lowering emissions varies significantly when considering waste glass landfilling. Moreover, this study evaluates the potential impacts on asphalt and reinforced concrete pavements (RCP) with 5 %, 10 %, 15 %, and 20 % replacement of natural sand with recycled glass aggregate. The LCA emphasizes the limitations of energy-intensive waste glass reprocessing. The obtained results and uncertainty analysis based on primary MRF data and recycled product applications provide meaningful suggestions for a more fit-for-purpose waste management and natural resource conservation.
本研究旨在对混合玻璃废物（MGW）回收工艺进行全面的生命周期评估（LCA），以量化作为天然骨料部分替代品的碎玻璃的环境影响。在材料回收设施（MRF）中进行的上游清洗、破碎和分类是评估再生 MGW 在路面建设中是否为可行替代方案的主要活动。以前的研究都没有明确从环境角度考虑废物玻璃上游工艺的相对不确定性和优化。该研究使用生命周期评估工具 SimaPro 计算环境影响，考虑与运输、电力消耗、化学物质使用和再加工玻璃废物用水相关的设计因素。通过执行详细的蒙特卡罗模拟，验证了设计变量的相对不确定性和国家过渡政策（2021-2030 年）从不可再生能源向可再生能源的转变。连续变量的相关系数（r=0.64、0.58 和 0.49）解释了玻璃回收过程中较高的环境收益如何被柴油、能源消耗和运输距离所抵消。与天然采石场砂相比，通过破碎和再利用其副产品生产的再生玻璃骨料分别减少了 16.2%和 46.7%的 COeq 排放。除了破碎之外，工厂还需要一条清洗线，这导致其环境影响比天然砂高 90.1%，并强调了通过单独的垃圾桶收集废玻璃的好处，从而避免了污染。结果表明，考虑到废玻璃的填埋，降低排放的好处会有显著的差异。此外，本研究还评估了将 5%、10%、15%和 20%的天然砂用再生玻璃骨料替代后，对沥青和钢筋混凝土路面（RCP）的潜在影响。LCA 强调了能源密集型废玻璃再加工的局限性。基于主要 MRF 数据和再生产品应用的研究结果和不确定性分析为更适合用途的废物管理和自然资源保护提供了有意义的建议。
