A Journey towards Sustainable Small Wastewater Treatment Systems in Low and Lower–Middle Income Countries
Doctoral thesis, 2020

The sustainability of small wastewater treatment systems (WWTSs) in low and lower-middle income countries represents a challenge in terms of functionality and optimal performance in the ongoing effort to treat wastewater sufficiently to enable safe discharge or reuse. The reuse of wastewater is a common practice in these countries, especially where water resources are scarce. However, current practice does not always ensure that public health risks are avoided. The sustainable development goals (SDGs) include the target of halving the proportion of untreated wastewater by 2030 (SDG 6.3). To achieve this, it is crucial to identify and understand the challenge of having sustainable WWTSs that operate optimally, and to support the formulation of effective strategies for implementing more sustainable systems. In this thesis, a case study approach was used to investigate nine small WWTSs in Cochabamba, Bolivia. A WWTS consists of the collection system, i.e. the sewer network, and the wastewater treatment plant (WWTP). Quantitative data was collected in the field from the WWTPs and qualitative data was collected regarding the sewer network and the users. A body of knowledge was built up dealing with the specific difficulties experienced at these WWTSs in achieving optimal performance and how the actual performance impacts on human health and ecological risks in areas where wastewater irrigation is practised. This body of knowledge was used to acquire a greater understanding of how the sustainability of small WWTSs can be assessed. Systematization of standard sustainability indicators was used and contextualized further with the aid of participatory methods involving local stakeholders. A key finding was that a lack of institutional capacity to implement adequate treatment systems and provide local technical expertise, along with a lack of financial resources, prevented the WWTPs from performing optimally. The performance of the WWTPs was also affected by issues in the sewer network resulting from design problems or inadequate use. In this context there were five relevant sustainability dimensions for assessment of small WWTSs: institutional, social, economic, technical, and environmental. The list of contextualized sustainability indicators and the knowledge acquired led to the development of a sustainability assessment tool, EVAS (Evaluation of Sustainability/Evaluación de Sostenibilidad), for small WWTSs during the operational stage. The aim of the EVAS tool is to enable managers of small WWTSs and local decision-makers to assess the current status of their WWTSs and support the formulation of strategies to improve their sustainability.

sustainability assessment

sustainability indicators

low and lower-middle income countries

performance assessment

institutional dimension

EVAS tool (EVAluation of Sustainability)

Wastewater treatment system

operation and maintenance

local stakeholders

resource recovery

Opponent: Associate Professor Miller Alonso Camargo-Valero, School of Civil Engineering, University of Leeds, UK


Claudia Cossio Grageda

Chalmers, Architecture and Civil Engineering, GeoEngineering

Wastewater management in small towns - understanding the failure of small treatment plants in Bolivia

Environmental Technology (United Kingdom),; Vol. 39(2018)p. 1393-1403

Journal article

Manuscript-Claudia Cossio, Jennifer R. McConville, Ann Mattsson, Alvaro Mercado, and Jenny Norrman. Developing a tool for sustainability assessment of small wastewater treatment systems in low and lower-middle-income countries.

Sustainable wastewater treatment is crucial to safeguard human health and the environment. Wastewater treatment can also promote environmental sustainability through the recovery of resources from the wastewater such as water, biofertilizer and energy. Sustainable Development Goal 6 – Clean Water and Sanitation aims to ensure global availability and sustainable management of water and sanitation. More specifically, target 6.3 aims to halve the proportion of untreated wastewater by 2030, which will require effective management of wastewater treatment systems (WWTSs) to be achieved. In low and lower-middle income countries, 80% of the wastewater produced is discharged without treatment. In this thesis, the specific difficulties encountered in small WWTSs in Bolivia, a lower-middle income country were analysed, along with the effects on the systems’ performance and the potential ecological and human health risks associated with wastewater irrigation. Based on these studies, the EVAS tool (EVAluation of Sustainability/EVAluación de Sostenibilidad) was developed to assess the sustainability of small WWTSs. The tool includes five sustainability dimensions (technical, environmental, social, economic, and institutional): each dimension includes sustainability indicators adapted to the context of low and lower-middle income countries. The institutional dimension was considered to be particularly critical by local stakeholders as it enables technical performance, achieving environmental goals, positive social interaction, acceptability, and financial viability. The assessment results can be used to support managers and local decision-makers regarding the formulation of strategies for improvement of small WWTSs.

Integrated Water Resource Management (IRWM) – Water Quality, Pollution and Treatment

SIDA, 2018-06-30 -- 2019-12-31.

SIDA, 2013-04-01 -- 2017-12-31.

Driving Forces

Sustainable development

Subject Categories

Other Engineering and Technologies

Environmental Engineering



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4748


Chalmers University of Technology



Opponent: Associate Professor Miller Alonso Camargo-Valero, School of Civil Engineering, University of Leeds, UK

More information

Latest update

6/3/2020 9