Comparison of municipal solid waste treatment scenarios through the technique of Life Cycle Assessment: the case of the city of Garibaldi, RS, Brazil

ABSTRACT The Life Cycle Assessment (LCA) has emerged as an effective technique to evaluate municipal solid waste management systems (MSW), serving as support for decision making of the best model to be adopted. The objective of this research was to analyze scenarios through the LCA technique in the city of Garibaldi, Rio Grande do Sul, Brazil, comparing different alternatives of treatment and final disposal of MSW under the environmental aspect, and contribute to decision making, based on the study of the city of Garibaldi (RS). Five scenarios were simulated integrating processes such as recycling, composting, anaerobic digestion and incineration, for which the Life Cycle Inventory was prepared by means of the IWM-2 software, which calculates the evaluated treatment technologies by products and their respective life cycle inventories, in terms of energy consumption, emissions to water, air, and soil. For the Life Cycle Impact Assessment, calculations were applied to the categories of environmental impact, namely climate change, photo-oxidants formation, acidification, eutrophication and human toxicity, and indicators of energy use and recyclable and organic waste disposal into landfills. The scenarios that contemplated recycling associated with composting, recycling associated with anaerobic digestion followed by composting, and recycling associated with composting with incineration of waste and with energy recovery presented the best environmental performance, so they are indicated as possible treatment solutions for municipal solid waste in the case that was analyzed.

摘要 生命周期评估（Life Cycle Assessment, LCA）现已成为评估城市固体废物管理系统（municipal solid waste management systems, MSW）的有效技术手段，可为最优管理模式的决策制定提供科学支撑。本研究以巴西南里奥格兰德州加里波第市为研究对象，采用LCA技术对多类场景展开分析，从环境维度对比城市固体废物的不同处理与最终处置方案，以期为相关决策提供参考依据。

本研究共设置五类模拟场景，整合了回收、堆肥、厌氧消化及焚烧等处理流程；研究依托IWM-2软件为各场景编制了生命周期清单，该软件可针对所评估的处理技术及其副产物与对应生命周期清单，从能源消耗、向水、大气与土壤的排放等维度开展量化计算。

在生命周期影响评估环节，本研究针对气候变化、光化学臭氧形成、酸化、富营养化及人体毒性等环境影响类别，以及能源使用、可回收物与有机废物填埋处置等指标开展了量化计算。

结果显示，涵盖回收与堆肥联用工艺、回收结合厌氧消化后再辅以堆肥，以及回收配合堆肥与焚烧并实现能源回收的三类场景，展现出最优的环境绩效，因此可作为本次研究案例中城市固体废物的可行处理方案。