A multi-criteria decision framework for circular wastewater systems in emerging megacities of the Global South

Andre Torre; Ian Vázquez-Rowe; Eduardo Parodi; Ramzy Kahhat

doi:10.1016/j.scitotenv.2023.169085

A multi-criteria decision framework for circular wastewater systems in emerging megacities of the Global South

Sci Total Environ. 2024 Feb 20:912:169085. doi: 10.1016/j.scitotenv.2023.169085. Epub 2023 Dec 5.

Authors

Andre Torre¹, Ian Vázquez-Rowe², Eduardo Parodi¹, Ramzy Kahhat¹

Affiliations

¹ Peruvian LCA & Industrial Ecology Network (PELCAN), Department of Engineering, Pontificia Universidad Católica del Perú, Avenida Universitaria 1801, San Miguel 15088, Lima, Peru.
² Peruvian LCA & Industrial Ecology Network (PELCAN), Department of Engineering, Pontificia Universidad Católica del Perú, Avenida Universitaria 1801, San Miguel 15088, Lima, Peru. Electronic address: ian.vazquez@pucp.edu.pe.

PMID: 38056636
DOI: 10.1016/j.scitotenv.2023.169085

Abstract

Lima faces increasing water stress due to demographic growth, climate change and outdated water management infrastructure. Moreover, its highly centralized wastewater management system is currently unable to recover water or other resources. Hence, the primary aim of this study is to identify suitable wastewater treatment alternatives for both eutrophication mitigation and indirect potable reuse (IPR). For eutrophication mitigation, we examined MLE, Bardenpho, Step-feed, HF-MBR, and FS-MBR. For IPR, we considered secondary treatment+UF + RO + AOP or MBR + RO + AOP. These alternatives form part of a WWTP network at a district level, aiding Lima's pursuit of a circular economy approach. This perspective allows reducing environmental impacts through resource recovery, making the system more resilient to disasters and future water shortages. The methods used to assess these scenarios were Life Cycle Assessment for the environmental dimension; Life Cycle Costing for the economic perspective; and Multi-Criteria Decision Analysis to integrate both the quantitative tools aforementioned and qualitative criteria for social and techno-operational dimensions, which combined, strengthen the decision-making process. The decision-making steered towards Bardenpho for eutrophication abatement when environmental and economic criteria were prioritized or when the four criteria were equally weighted, while HF-MBR was the preferred option when techno-operational and social aspects were emphasized. In this scenario, global warming (GW) impacts ranged from 0.23 to 0.27 kg CO₂eq, eutrophication mitigation varied from 6.44 to 7.29 g PO₄^- equivalent, and costs ranged between 0.12 and 0.17 €/m³. Conversely, HF-MBR + RO + AOP showed the best performance when IPR was sought from the outset. In the IPR scenario, GW impacts were significantly higher, at 0.46-0.51 kg CO₂eq, eutrophication abatement was above 98 % and costs increased to ca. 0.44 €/m³.

Keywords: Circular economy; Climate change; Decentralization; Eutrophication; Life cycle assessment; MCDA.