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William Tarpeh
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Assistant Professor of Chemical Engineering

William Tarpeh

Faculty Affiliate
King Center on Global Development

Assistant Professor
Department of Chemical Engineering

Assistant Professor (by courtesy)
Department of Civil and Environmental Engineering

Center Fellow
Woods Institute for the Environment

William Tarpeh is an assistant professor of chemical engineering and an assistant professor by courtesy of civil and environmental engineering at Stanford. He is also a fellow of the Woods Institute for the Environment and a member of Bio-X. He holds a BS in chemical engineering from Stanford University and MS and PhD degrees in environmental engineering from the University of California, Berkeley. 

Tarpeh’s research is concerned with reimagining liquid waste streams as resources, with the goal of discovering more efficient, less costly approaches to reducing harmful discharges to the environment. His lab, the Tarpeh Lab, develops and evaluates novel approaches to resource recovery from “waste” waters at several synergistic scales. With the Lab, he leverages electrochemistry, separations, thermodynamics, kinetics, and reactor design to preferentially recover resources from waste. These molecular-scale insights are applied to increase the sustainability of engineered processes in terms of energy, environmental impact, and cost.


King Center Supported Research

2020 - 2021 Academic Year | Junior Faculty Research Grant

Reimagining Excreta as a Resource: Developing and Evaluating Techniques to Valorize Urine and Accelerate Sustainable Sanitation Access

Reimagining liquid waste streams as resources can lead to recovery of valuable products and more efficient, less costly approaches to reducing harmful discharges to the environment. Pollutants in effluent streams can be captured and used as valuable inputs to other processes. For example, municipal wastewater contains resources like energy, water, nutrients, and metals. The Tarpeh Lab develops and evaluates novel approaches to resource recovery from “waste” waters at several synergistic scales: molecular mechanisms of chemical transport and transformation; novel unit processes that increase resource efficiency; and systems-level assessments that identify optimization opportunities. We employ understanding of electrochemistry, separations, thermodynamics, kinetics, and reactor design to preferentially recover resources from waste. We leverage these molecular-scale insights to increase the sustainability of engineered processes in terms of energy, environmental impact, and cost.

2019 - 2020 Academic Year | Junior Faculty Research Grant

Wastewater Mining: Detecting SARS-CoV-2 and Extracting Marketable Disinfectant from Fecal Sludge in Dakar, Senegal

Globally, over one billion people live in informal settlements, where population growth outpaces essential infrastructure services such as water, electricity, and sanitation. Residents of informal settlements are especially vulnerable to the spread of COVID-19. In this research, the Tarpeh Lab leverages an existing network of fecal sludge treatment plants as a source of COVID-related disinfectants and diagnostics, reimagining excreta as a source of information rather than waste. The lab anticipates that its findings will improve public health in informal settlements by slowing the spread of COVID-19, and shortening the time for public health measure implementation using commonly overlooked information contained in fecal sludge.

2018 - 2019 Academic Year | Junior Faculty Research Grant

Engineering Agricultural Resilience After Natural Disasters: Deployable Fertilizer Production to Rehabilitate Arable Land

Cyclone Idai, which destroyed over 750,000 hectares of arable land in Mozambique, Malawi, and Zimbabwe, was one of the worst weather-related disasters in one of the poorest regions of the world. Globally, climate change increases the frequency and severity of natural disasters, which wreak disproportionate impacts on the lives and livelihoods of burgeoning populations in developing regions. Recovering fertilizer from waste accelerates rehabilitation of communities affected by natural disasters by increasing agricultural productivity, reducing diarrheal disease, and generating income. The objective of this research is to support fertilizer production for natural disaster rehabilitation. The project includes efforts to create field-ready devices, demonstrate on-site fertilizer production from excreta at scale, and solicit feedback from potential users. Work in each of these areas overlaps to enrich laboratory development with field insights and vice versa.

2019 - 2020 Academic Year | Capacity Building and Policy Engagement Grant

Building Capacity for Circular Economy Sanitation Research and Practice in Senegal

Sustainable sanitation access is one of the world’s most formidable development challenges. While 40% of the world’s population lacks regular access to toilets, 4.1 billion people’s health, livelihoods, and environments are compromised by limited access to excreta treatment. Creating value from waste can generate revenue and reduce healthcare and productivity costs while preventing diarrheal deaths. This project aims to build local capacity to develop and evaluate circular economy technologies for sustainable sanitation access in Dakar, Senegal. This goal is achieved through three major activities, including courses for policymakers, policy meetings, and partnership building.