Department Sanitation, Water and Solid Waste for Development
Carbonization of Urban Bio-waste
Slow pyrolysis refers to the thermal decomposition (breakdown under heat) of biomass into a carbon-rich solid residue (char), with gases and liquids as by-products. This process does not require highly complex engineered systems and has already been applied to transform agricultural waste into char. Our projects target urban bio-waste treatment by slow pyrolysis.
The project “Carbonization of Urban Bio-waste in Dar es Salaam” is a research collaboration with the University of Dar es Salaam (College of Engineering and Technology) in Tanzania. The overall objective is to explore the potential of slow pyrolysis as a treatment and valorisation method for organic solid waste.
Publications Slow Pyrolysis
- Pyrolysis of Biowaste in Low and Middle Income Settings. A Step-by-Step Manual.Zabaleta I., Bulant N., Pfyffer B., Rohr M., Ivumbi E., Mwamlima P., Rajabu H.M., Zurbrügg C. (2018). This publication provides knowledge on a low-tech and cheap technology alternative for slow pyrolysis of urban biowaste. The output, the char, can be used as renewable fuel but also as soil amendment (biochar). This manual is for practical use. It lists all materials, equipment and actions that are required to build and operate a reactor.[19.2MB]
- Char fuel production in developing countries – A review of urban biowaste carbonization.Ch. Lohri, H.M. Rajabu, D. J. Sweeney, Ch. Zurbrügg (2016) This article reviews existing carbonization technologies and explores the potential of char production to tackle both solid waste and cooking fuel challenges simultaneously.[644KB]
- Carbonization of urban biowaste in Dar es Salaam (Tanzania) Phase III. Pfyffer, B. (2016)[3.4MB]
- Slow Pyrolysis of Urban Biowaste in Tanzania – An Analysis of the Technical and Socio-Economic Potential. Zabaleta, I., Rohr, M., Zermin, F., Mtoro Rajabu, H., Zurbrügg, C. (2016)[836KB]
- Lohri, C.R., Sweeney, D., Rajabu, H.M. (2015): Carbonizing urban biowaste for low-cost char production in developing countries – A review of knowledge, practices and technologies. Joint report by Eawag, MIT D-Lab and UDSM.
- Lohri, C.R., Faraji, A., Ephata, E., Rajabu H.M., Zurbrügg, C. (2015): Urban biowaste for solid fuel production: Waste suitability assessment and experimental carbonization in Dar es Salaam, Tanzania. Waste Management & Research, Vol. 33(2), 175-182.
Hydrothermal Carbonization (HTC) is a thermochemical reaction that occurs in a pressurized reactor when a mix of organic matter and water is heated for several hours. In contrast to dry pyrolysis, HTC can process substrate that has a high moisture content, making it suitable for the wet fraction of municipal organic solid waste.
For experimental purposes, a bench scale prototype reactor that can handle 20 litres has been conceived, constructed, and is presently being tested. Current objectives are: i) to define optimal operational parameters and ii) to explore measures to increase the energy efficiency and autonomy of the HTC process.
Publications HTC
- Improving the energy-related aspects of biowaste treatment in an experimental hydrothermal carbonization reactorLohri, C.R., Zabaleta, I., Rohr, M., Baier, U., Zurbrügg, C. (2016). This article presents the merits of mild hydrothermal carbonization and provides information for energy optimization of an HTC system[793KB]
- Robbiani, Z. (2013). Hydrothermal carbonization of bio-waste/faecal sludge.
Conception and construction of a HTC prototype research unit for developing countries. Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland. (MSc Thesis, ETH) - Dea Marchetti, P. (2014). Hydrothermal carbonization of food waste.
Testing of an HTC prototype research unit for developing countries. (MSc Thesis, Sandec/University of Pavia).