Resource-oriented sanitation: Identifying appropriate technologies and environmental gains by coupling Santiago software and life cycle assessment in a Brazilian case study

Abstract

Implementation of resource recovery technologies is becoming increasingly important, as humans are exhausting the world's natural resources. Recovering nutrients and water from wastewater treatment systems will play an important role in changing the current trends towards a circular economy. However, guidance is still needed to determine the most appropriate way to do this. In this study two decision-support tools, sanitation planning software (Santiago) and life cycle assessment (LCA), were applied to identify appropriate technologies and their environmental impacts. As a case study, current and alternative scenarios for a wastewater treatment plant (WWTP) in Campo Grande, west-central Brazil, were used. Among 12 scenarios provided by Santiago for efficient nutrient recovery, eight were selected for further assessment. The current WWTP system (UASB reactors) resulted in the highest negative impacts in two of nine assessment categories (freshwater and marine eutrophication), due to nutrient discharge to water. A source separation scenario with urine stored in a urine bank and co-composting of feces showed best overall performance. Electricity consumption played a crucial role for impacts in several categories, while water consumption was not significantly affected by choice of toilet. One Santiago scenario matched the most appropriate scenario with the best environmental performance, but the other seven scenarios were not as beneficial, indicating a need for some adjustments in the software. These results highlight the importance of performing LCA to compare alternative scenarios, even when using a tool designed to identify locally appropriate technologies. The results also indicate that the current wastewater treatment system has reasonable environmental performance, but could be improved if measures were taken to recover energy and reuse water.

Keywords: Decision-making; Environmental burden; Nutrient recovery; Wastewater treatment plant (WWTP).