Sustainability Analysis of a Municipal Wastewater Treatment Plant through Emergy Evaluation

Abstract

Water and wastewater treatment plants are essential for the supply of drinking water for consumption and the treatment of effluents produced by human/industrial activities. However, few studies deal with the investments and sustainability of these services, which consider both the contribution of nature and society. This study uses the emergy approach to evaluate a wastewater treatment plant located in the northeastern part of Romania, in Iași city. An assessment of the environmental costs of natural fluxes required for the treatment processes was performed, considering that the treated effluent is, still, loaded with contaminants that have to be absorbed by the receiving water natural system. The work done by nature to assimilate this load, generally considered free, is esteemed as a further cost in the total emergy budget of the wastewater treatment processes. The sustainability perspective was approached by calculating and analyzing the emergy yield ratio (EYR), environmental load rate (ELR), and emergy sustainability development index (ESI). The use of local renewable natural resources in Iași municipal wastewater treatment plants is negligible (1.71% of the total plant emergy budget), as compared to that of the purchased resources (98.29% of the total plant emergy budget) mainly processed with the support of fossil fuels’ generated energy. The unit emegy value was, also, calculated and compared to other studies relevant for wastewater treatment plants. The analysis suggests that the large amount of emergy that wastewater contains is proportional to the number of resources employed for wastewater treatment and the extensive effects on surrounding ecosystems, where wastewater is discharged.

Global Research Trends in Emergy and Wastewater Treatment: A Bibliometric Analysis

“…It is observed that 8 of the 10 most cited documents correspond to the period before 2010 and only two were published after 2015. Research reports emergy analysis in different scenarios: constructed wetlands (Arias and Brown, 2009;Chen et al, 2009;Siracusa and la Rosa, 2006;Zhou et al, 2009), municipal wastewater (Björklund et al, 2001;Ciobanu et al, 2022), organization system (Bastianoni and Marchettini, 1997) and specifically water treatment with microalgae (Grönlund et al, 2004).…”

“…This is what is really important to treat wastewater from different activities using technology. Furthermore, it is necessary to apply some environmental management instruments to quantify the activities of humans that cause direct and indirect effects on the environment, to enable decision-makers to track and measure progress towards sustainability goals and outcomes (Ciobanu et al, 2022). Some of these instruments could be Life Cycle Assessment (LCA) (Bonton et al, 2012;Raghuvanshi et al, 2017), water footprint (Huang et al, 2022;Johnson and Mehrvar, 2019;Romeiko, 2019), exergy analysis (Li et al, 2021) and emergy analysis (Ciobanu et al, 2022;Liu et al, 2022).…”

“…A method that is suitable from the sustainable development perspective has to consider all interactions between environmental, social, and economic impacts of wastewater treatment systems. Emergy could provide a holistic approach and a unified measurement for sustainability evaluation (Ciobanu et al, 2022).…”

Assessing the Quality of Treated Wastewater for Irrigation: A Case Study of Ain Sefra Wastewater Treatment Plant

“…Currently, there is a growing global interest in the reuse of wastewater as a strategy to ensure a consistent water supply for agriculture [23,24]. Many studies have been conducted to evaluate the effectiveness of this technique [25,26].…”