Design, Numerical Optimization and Implementation of a Sludge Pasteurization System


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Date

2025-10-13

Publication Type

Master Thesis

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yes

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Abstract

In Malawi, access to basic sanitation is still not guaranteed for all citizens. As a result, basic human hygiene cannot be ensured, which poses risks to public health. The aim of this thesis is to develop an anaerobic digestion pasteurization system for a specific Sistema.bio digestion reactor, such that it can be operated exclusively with self-produced biogas from the digestion in order to eliminate 90 % of harmful pathogens in fecal sludge, which can then be used as safe fertilizer. With the use of analytical calculations for chemical reactions, heating power, volumes, and heat transfer efficiencies, each component (heat exchanger, pasteurizer tank, burner and buffer tank) is designed to accommodate the digester. Subsequently, numerical flow simulations were used to optimize and theoretically verify the function and interaction of each system part. Finally, with a test setup, some of the components were tested in a controlled environment. To accommodate the Sistema.bio digesters, a final pasteurization tank with a volume of 80 Liter, a plate heat exchanger, and biogas burner were designed. With the simulated and tested efficiencies, the self-produced biogas is sufficient to operate the system, with some unutilized biogas left for other applications. As far as the theory and the tested components go, the system will work, but further work with prototyping is required to end the test phase.

Publication status

published

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ETH Zurich

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Subject

Sludge Pasteurization System; Malawi; Sanitation

Organisational unit

09746 - Tilley, Elizabeth / Tilley, Elizabeth check_circle

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