The biofactory : implementing a life cycle sustainability assessment decision making tool for quantifying integral sustainability benefits of the wastewater circular economy in Chile.

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Theses / Dissertations
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Thesis discipline
Civil Engineering
Degree name
Doctor of Philosophy
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Language
English
Date
2023
Authors
Furness, Madeline
Abstract

The “Biofactory” is a circular economy-based concept for wastewater treatment that improves water quality, promotes efficient use of materials and energy, recovering resources, generating stakeholder collaboration, and decreasing both emissions and costs. This proposes a solution for the global challenge of integrated water and sanitation management. Due to socio-economic bottlenecks, such as typical high costs and low public acceptance of novel resource recovery scenarios in wastewater treatment, realizing the Biofactory goals becomes a difficult task. Decision makers are currently unable to appreciate the environmental and social benefits of the Biofactory, as most decision-making tools focus on mainly technical and economic aspects. This research is the first to quantify integral sustainability benefits of co-product recovery of treated effluent, biosolids, biogas and nutrient in two full-scale “Biofactory” wastewater circular economies in Chile. Life Cycle Sustainability Assessment (LCSA) was implemented, combining Life Cycle Assessment (LCA), Social Life Cycle Assessment (SLCA) and Life Cycle Costing (LCC) with a Multi-criteria Decision Making (MCDM) model to quantify integral environmental, socio-cultural, and economic sustainability impacts of two Plants, A and B. Three scenarios for each plant were considered, discharge of wastewater without treatment, conventional wastewater treatment with no resource recovery, and biofactory wastewater circular economy configurations, to determine if each plant decrease impacts and determine which had better performance. LCA results showed Plant A decreased overall environmental impact by -37 % compared to baseline conventional scenarios, while Plant B -31 %. SLCA results showed Plant A decreased social impacts – 56 %, while Plant B – 18 %, therefore, Plant A had better overall environmental and social performance. However, Plant B decreased economic impacts by -48 % compared to an increase of 20 % in Plant A. Therefore, when combining scores using a MCDM model, Plant A decreased total sustainability impacts by -30 % and Plant B by -58 %, therefore, the resource recovery systems implemented in Plant B had better overall sustainability performance. These results were discussed across process contributions to environmental, social, and economic benefits. Model limitations were discussed, and recommendations were made for future applications of this research. The investigation demonstrated that the transition to WW-CEs improved integral sustainability according to the LCSAMCDM model implemented in both Plants. The urgent need to adopt sustainable decision-making models was highlighted and discussed, to not only improve sanitation coverage, but also improve sustainability performance of the sanitation industry across the globe.

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