Sustainability assessment of urban and peri-urban sanitation systems relevant in the Bolivian context

The report introduces a technology-neutral sustainability assessment method based on five pillars: social, environmental, economic, health and hygiene, and technical/institutional sustainability. Applying this to Montero, Bolivia, the study compares four systems: conventional gravity-fed sewers (System 1), condominial sewers (System 2), septic tanks with soak pits (System 3), and urine-diverting dry toilets (UDDTs) (System 4). Findings indicate that while conventional systems have high social acceptability, they are the least affordable and most vulnerable to water scarcity and flooding. System 4 (UDDTs) performs best in health, water use, and climate resilience. Optimization—such as adding inlet screens, using personal protection equipment (PPE), and implementing scheduled emptying—generally improves health and environmental outcomes but increases technical complexity and reduces economic sustainability. The report argues for a city-wide inclusive sanitation approach using a mix of these systems to balance trade-offs between cost, health, and environmental protection.

• The proposed sustainability assessment method is technology-neutral and utilizes a multi-criteria assessment approach with strong stakeholder involvement to identify strengths and weaknesses across the sanitation service chain.
• In the Montero case study, System 1 (conventional gravity-fed sewers) is characterized by high social acceptability and technical complexity but suffers from low household affordability, high vulnerability to flooding and water scarcity, and poor economic sustainability.
• System 4 (Urine-diverting dry toilets) demonstrated the highest performance in health and hygiene, water use, and resilience to water scarcity among the evaluated systems.
• None of the existing sanitation systems in Montero remove nutrients (total nitrogen and total phosphorus) and biological oxygen demand (BOD5) to a satisfactory level.
• Optimizing systems through low-cost interventions, such as the use of personal protection equipment (PPE) and improved operation and maintenance routines, increases health and hygiene sustainability.
• Optimized System 4, which includes urine collection services, achieves the highest environmental protection of all systems but experiences a significant drop in economic sustainability.
• Conventional sewered systems (Systems 1 and 2) exhibit inherent technical inflexibility, making it difficult to improve their vulnerability to flooding, water scarcity, and household affordability through optimization.
• System 1 is heavily subsidized compared to other options, and the report argues that all sanitation system types should have access to similar financing mechanisms and subsidy levels.
• Innovations such as Up-flow anaerobic sludge blanket (UASB) reactors and chemical precipitation can improve effluent quality and increase plant capacity for System 1, though they increase technical complexity and costs.
• For System 2, replacing gravel filters with submerged aerated filters (SAF) can significantly improve the removal of organic matter (BOD or COD) by up to 90%.
• The use of urea treatment for faecal sludge in System 3 creates an alkaline environment that inactivates pathogens, producing a safer product for agricultural reuse.
• Innovations for System 4, including urine stabilization at the household level and solar-powered urine drying, can reduce the mass of urine by 90% while maintaining high nutrient levels for fertilizer.

APA

Kvarnström, E., Ahlström, M., Andersson, K., & Heredia, G. (2023). Sustainability assessment of urban and peri-urban sanitation systems relevant in the Bolivian context. Stockholm Environment Institute. https://www.sei.org/wp-content/uploads/2023/01/montero-sanitation-sei2023.003.pdf

Chicago

Kvarnström, Elisabeth, Markus Ahlström, Kim Andersson, and Gustavo Heredia. Sustainability assessment of urban and peri-urban sanitation systems relevant in the Bolivian context. Stockholm Environment Institute, 2023. https://www.sei.org/wp-content/uploads/2023/01/montero-sanitation-sei2023.003.pdf.

Wikipedia

{{cite report |last1=Kvarnström |first1=Elisabeth |last2=Ahlström |first2=Markus |last3=Andersson |first3=Kim |last4=Heredia |first4=Gustavo |title=Sustainability assessment of urban and peri-urban sanitation systems relevant in the Bolivian context |publisher=Stockholm Environment Institute |date=January 2023 |url=https://www.sei.org/wp-content/uploads/2023/01/montero-sanitation-sei2023.003.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{kvarnstrm2023sustainability, author = {Kvarnström, Elisabeth and Ahlström, Markus and Andersson, Kim and Heredia, Gustavo}, title = {{Sustainability assessment of urban and peri-urban sanitation systems relevant in the Bolivian context}}, institution = {Stockholm Environment Institute}, year = {2023}, month = jan, url = {https://www.sei.org/wp-content/uploads/2023/01/montero-sanitation-sei2023.003.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }