Doctoral Student: Sensing and Controlling the Large-Scale Anaerobic Digestion of Human Excreta to Minimize Health Risks and Carbon Emissions

The Global Health Engineering (GHE) group, part of the Department of Mechanical and Process Engineering at ETH Zürich, invites applications for a doctoral student position focused on optimising biogas production and effluent treatment. Our diverse team of environmental and mechanical engineers, economists, and social scientists is dedicated to addressing engineering challenges related to environmental and human health in resource-constrained countries. Guided by the UN's Sustainable Development Goals (SDGs), our research emphasises clean water and sanitation (SDG 6), sustainable cities and communities (SDG 11), and responsible consumption and production (SDG 12).

Recently, the commercialisation of low-cost, modular anaerobic digesters (also known as “biogas digesters” or “biogas plants”) has increased demand for this well-established, but far from optimised, technology. Much of the interest associated with the new systems comes from the need for the methane-rich biogas, which can be used as a sustainable source of cooking fuel. Components for pressurising, storing, and burning biogas have also become plentiful. However, the resulting effluent contains harmful concentrations of pathogens and must be treated further before it is safe for handling or disposal.

Biogas systems are in demand for their ability to produce biogas, a sustainable cooking fuel. However, the effluent from these digesters contains harmful pathogens and requires further treatment before it is safe for agricultural use.

This research will utilise at least 3, full scale (40 m3) anaerobic (biogas) digesters in Kenya and/or Malawi where the feedstock is excreta from school toilet blocks. By employing the same technology at multiple locations, the researcher will be able to test and compare multiple technical interventions at full scale. The goals are to 1) identify the sensors and control mechanisms to optimise biogas production, considering variable feedstock (quality and quantity); and 2) design, test and optimise low-cost technologies capable of destroying all pathogens in the resulting effluent.  Pilot studies on solar- and biogas-fuelled technologies are underway, but must be verified at scale.  

Direct motivation for this project is article 6 of the Paris Agreement which encourages international cooperation and allows high-income, high-polluting countries to meet their carbon reduction commitments affordably by funding carbon reducing activities in lower-income countries and claiming the carbon reductions for themselves. Specifically, Switzerland, under its CO2 Act aims to offset about 40 million tonnes of CO2 by 2030 – 10% of its national emissions – with over half of these offsets occurring abroad. One upcoming collaboration, helping to achieve this goal, is with Malawi and involves distributing 10,000 household biogas digesters to dairy farmers.

This role involves technology development and optimization, extensive sensor piloting (for methane, effluent, and Volatile Fatty Acids), large-scale data management, complex stakeholder interactions, and long-term research stays in sub-Saharan Africa. Developed technologies are expected to have a direct impact on solutions adopted by Switzerland and throughout the world (i.e., India, sub-Saharan Africa).

We seek a candidate who is equally passionate about scientific discovery and sanitation. The ideal candidate will have:

• Master's degree in environmental or mechanical engineering.
• Experience with environmental sampling, laboratory analysis, and sensors.
• Passion for prototyping, designing, and building.
• Willingness to travel and work in challenging conditions.
• Proficiency in a programming language (R, Python, Julia, JavaScript) for data analysis.
• Curious mind, positive attitude, and love for research.
• Excellent critical thinking and problem-solving skills.
• Desirable but not required: work experience in Sub-Saharan Africa and/or knowledge of Swahili.

We are a tight-knit team of about ten members who value transparency, openness, and the sharing of knowledge beyond traditional publications. Our commitment to open science means we share data, code, and designs under permissive licences, enabling others to build upon our work freely. We continuously reflect on and improve our work, driven by the belief that open dissemination can lead to global improvements.