Biogas and cement from carbon dioxide

While working as a PhD student in the Department of Biotechnology (Faculty of Applied Sciences), Dr Shiva Salek developed a process that combines wastewater treatment and CO2 fixation with the sustainable production of methane and cement. She received the Lettinga Award for this research.

Salek was the only participant at the Congress on Anaerobic Digestion (Santiago de Compostella, 2013) to have succeeded in using fermentation to produce raw materials plus CO2 fixation, for which she received the Lettinga Award with a value of € 25 ,000. Salek currently works as a product engineer at Lely Industries in Maassluis. The greenhouse gas carbon dioxide (CO2) is the main driver of climate change. As a PhD student, Dr Shiva Salek developed a process that fixes CO2, while also making use of sewage water and ground limestone. The end products are clean water, methane and raw materials for biocement, fertilisers or fillers (grout).

Step by step, calcium silicate (from limestone) is converted into calcium carbonate (CaCO3) by fixing CO2.

Calcium carbonate is a raw material used in the cement industry. The first step, dissolving the silicate, requires acidic conditions, while the second step, calcium carbonate precipitation, requires alkaline conditions.

Salek uses organic decomposition (anaerobic digestion) and the production of fatty acids to create acidic conditions and dissolve the calcium silicate. The production of methane at a later stage in the process increases the pH so that the calcium carbonate precipitates in alkaline conditions.


Shiva S. Salek et al., Mineral CO2 sequestration by environmental biotechnological processes, Trends in Biotechnology, March 2013.

Stay informed about the research

Receive the Delft Outlook newsletter 4 times a year