Life cycle assessment of wastewater treatment options for small and decentralized communities

• Published in: Water science and technology Vol. 56; no. 3; pp. 15 - 22
• Main Authors: Machado, A P, Urbano, L, Brito, A G, Janknecht, P, Salas, J J, Nogueira, R
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01-01-2007
• Subjects: Activated sludge process; Artificial wetlands; Carbon dioxide; Carbon dioxide emissions; Climate change; Construction materials; Depletion; Ecosystem; Emissions control; Energy conservation; Environmental impact; Global warming; High density polyethylenes; Infiltration; Life cycle analysis; Life cycle assessment; Life cycle engineering; Plant design; Residence Characteristics; Rural areas; Rural communities; Sustainability; Waste Disposal, Fluid - instrumentation; Waste Disposal, Fluid - methods; Waste Disposal, Fluid - standards; Wastewater treatment; Wastewater treatment plants; Water Purification; Water treatment plants; Wetlands
• ISBN: 9781843395980; 1843395983
• ISSN: 0273-1223; 1996-9732
• 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.