Addressing the rural wastewater treatment dilemma: A techno-environmental-economic analysis

• Rural areas face challenges in expanding costly urban sewer systems. • Decentralized wastewater treatment (DWT) offers a viable, sustainable alternative. • Life cycle assessment reveals DWT’s environmental benefits. • DWT saves 900 to 1300 €/PE over centralized treatment. • Our study guides decision-makers on sustainable wastewater solutions. Rural wastewater treatment presents a significant challenge, particularly in areas without sewer connections. The decision between onsite decentralized wastewater treatment (DWWT) and offsite sewer-based centralized wastewater treatment (CWWT) has been the subject of long-term debate in rural area. The complexity of rural wastewater treatment is influenced not only by the technological feasibility of DWWT for various rural wastewater streams but also by local wastewater legislation, geographic conditions, and economic factors, all of which contribute to the intricacies of rural wastewater treatment decision-making. For instance, the most common type of DWWT system—a septic tank with a drainfield (subsurface discharge)—is prohibited in Flanders due to concerns over groundwater contamination. Leveraging the demonstrated technological prowess of three DWWT systems in three representive rural wastewater streams, this study employs a life cycle assessment (LCA) framework to ascertain the environmental viability of these DWWTs as alternatives in Flanders’ rural areas. The LCA-based decision support tool offers a comprehensive means of comparing decentralized wastewater treatment (DWWT) and centralized wastewater treatment (CWWT) systems, particularly for remote and sparsely populated areas in Flanders. This tool takes into account variables such as the length of linking sewers and the volume of wastewater generated. The findings indicate that DWWT is a more sustainable option from both environmental and economic perspectives. The primary advantages of DWWT arise from avoiding the need for extensive sewer construction. When considering both capital and operational expenditures, DWWT presents significant cost savings, ranging from 900 to 1300 €/PE, compared to CWWT. This study makes a significant contribution to identifying tools for rural decision-making and development, thereby enhancing the sustainability and cost-efficiency of wastewater infrastructure.