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

Abstract

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.

Life cycle assessment of small-scale constructed wetland and extended aeration activated sludge wastewater treatment system

“…According to the legal standards stated by the Estonian authorities, 1 p.e. equals to 60 g of BOD per 24 h. This functional unit has used in previous LCAs (Dixon et al 2003;Hospido et al 2008;Lundin et al 2000;Machado et al 2006;Nogueira et al 2009) as an alternative to the quantity of inflow water. Since one of the chosen WWTP has a varying yearly water inflow, p.e.…”

“…In previous research, LCA of CW has been carried out where the filter system was built using only gravel, sand, rubble or splinters, soil, plants or compost (Brix 1999;Dixon et al 2003;Fuchs et al 2011;Machado et al 2006;Memon et al 2007). This case study differs due to the use Fig.…”

“…There have also been LCAs where the construction phase has been exempted based on the need to concentrate only on the performance (Muñoz et al 2006), or due to the fact that construction phase amounts little if compared to the impact of the whole life cycle . Some researchers have concluded that the demolition phase does not have a large impact and is, therefore, left out from the studied system boundary (Dixon et al 2003;Foley et al 2007;Machado et al 2006). According to Larsen and Hauschild (2008), the use of electricity, use of fuels and sludge treatment process increase the impact of the use phase.…”

Comparative Life Cycle Assessment (LCA) of Two On-Site Small-Scale Activated Sludge Total Oxidation Systems in Plastic and Vibrated Reinforced Concrete

“…For instance, for extensive treatment systems, i.e., constructed wetlands, the life cycle phase with the greatest impact could be the construction phase [5,[7][8][9].…”

El análisis del ciclo de vida aplicado a las plantas de tratamiento de aguas residuales

“…Se ha recomendado la implementación de un tratamiento terciario para la remoción de nutrientes . En otros estudios de ACV en PTAR, se han utilizado para la planificación y selección de la PTAR, incluyendo la variable ambiental en el diseño de la PTAR, dado que el ACV es una herramienta de toma de decisión para la disminución de impactos ambientales, y por eso, se incluye en el proceso de diseño de ingeniería de la PTAR (Machado, 2007). Algunas aplicaciones de ACV en PTAR, establecen que los impactos ambientales generados en la PTAR, como eutrofización y calentamiento global, son los factores más costosos y significativos.…”