During anaerobic digestion of organic residual streams, the core process in the production of biogas, sulfur-based compounds are often co-products. Especially hydrogen sulfide (H2S), which is unwanted since it is toxic for the workers on site and the environment. Therefore, some desulfurization strategies were developed to efficiently remove such compound from the biogas mixture.
One strategy currently developed in a project we are working on with partners is the catalytic oxidation of H2S into elemental sulfur (S0). This allows a clean separation resulting into a recovered stream of solid sulfur that can be further valorized into other products, such as sulfuric acid (H2SO4), which is a useful chemical to be used within the biogas facility itself. To make the biogas facility more circular our task within the project is to develop the step from S0 to H2SO4.
Some microorganisms, such as Acidithiobacillus thiooxidans can perform this bioconversion, while also fixation of carbon dioxide (CO2). This organism is known to be able to grow under extremely low pH. A nessessity when your product is a strong acid such as H2SO4.
In this project, the biological production of H2SO4 by Acidithiobacillus thiooxidans from S0 will be assessed and optimized under controlled laboratory conditions. The fermentation experiments will take place in shake flasks of different sizes, with predefined growth media. Different process parameters will be analyzed and compared, such as pH, sulfur particle size, and batch versus sequencing batch set up.
Analytical methods consist of spectrophotometry for microbial growth, and the development of an adequate protocol for measurements of produced H2SO4 through turbidity tests (spectrophotometry) or titration.
At some point in the project the need for microbial identification by DNA techniques might also be investigated.
If you have experience with fermentation and have an open and curious mind, you are in the right place. HBO students with a suitable background are welcome to apply.
You will be working for the research group Biobased Resources & Energy within the center of expertise MNEXT – Material and Energy Transition. MNEXT is powered by the Avans and HZ Universities of Applied Sciences and helps businesses achieve their biobased goals by working with them to modernize higher professional education and to carry out applied research that makes a difference. The Biobased Resource & Energy research group is focused on valorizing residual streams from nature, agriculture or industrial sources, and the production and use of biobased energy.
You will be provided with a monthly payment of €350.