Machado A P, Urbano L, Brito A G, Janknecht P, Salas J J, Nogueira R
University of Minho, Institute of Biotechnology and Bioengineering, Centre of Biological Engineering, Campus de Gualtar, 4710-057 Braga, Portugal.
Water Sci Technol. 2007;56(3):15-22. doi: 10.2166/wst.2007.497.
Sustainability has strong implications on the practice of engineering. Life cycle assessment (LCA) is an appropriate methodology for assessing the sustainability of a wastewater treatment plant design. The present study used a LCA approach for comparing alternative wastewater treatment processes for small and decentralised rural communities. The assessment was focused on two energy-saving systems (constructed wetland and slow rate infiltration) and a conventional one (activated sludge process). The low environmental impact of the energy-saving wastewater treatment plants was demonstrated, the most relevant being the global warming indicator. Options for reduction of life cycle impacts were assessed including materials used in construction and operational lifetime of the systems. A 10% extension of operation lifetime of constructed wetland and slow rate infiltration systems led to a 1% decrease in CO2 emissions, in both systems. The decrease in the abiotic depletion was 5 and 7%, respectively. Also, replacing steel with HDPE in the activated sludge tank resulted in a 1% reduction in CO2 emission and 1% in the abiotic depletion indicator. In the case of the Imhoff tank a 1% reduction in CO2 emissions and 5% in the abiotic depletion indicator were observed when concrete was replaced by HDPE.
可持续性对工程实践有着重大影响。生命周期评估（LCA）是评估污水处理厂设计可持续性的一种合适方法。本研究采用LCA方法比较小型分散农村社区的替代污水处理工艺。评估重点关注两种节能系统（人工湿地和慢速渗滤）以及一种传统系统（活性污泥法）。结果表明节能污水处理厂对环境的影响较小，其中最显著的是全球变暖指标。评估了减少生命周期影响的方案，包括系统建设中使用的材料和运行寿命。人工湿地和慢速渗滤系统运行寿命延长10%，两个系统的二氧化碳排放量均降低1%。非生物耗竭分别降低了5%和7%。此外，在活性污泥池中用高密度聚乙烯（HDPE）替代钢材，二氧化碳排放量降低1%，非生物耗竭指标降低1%。在英霍夫池的案例中，当用HDPE替代混凝土时，二氧化碳排放量降低1%，非生物耗竭指标降低5%。
