Development of new biological desulfurization processing schemes

In the transition from fossil fuel to renewable energy, sulfur will become a scarce resource. Currently, the worldwide sulfur market is determined by the recovery of sulfur as a by-product when oil and gas are exploited. This project focuses on the removal of H2S from (bio)gas streams and conversion into usable elemental sulfur using recently discovered features of a community of chemolithotrophic sulfide oxidizing bacteria (SOB). Biologically produced elemental sulfur is commonly recovered as crystals with hydrophilic properties. This is distinctively different when compared to chemical produced sulfur and can be beneficial, e.g., for agricultural purposes. A challenge in biological sulfur conversion is to limit the unwanted production of sulfate. It has been recently found that SOB possess shuttling capacity, thanks to which bacteria can (i) remove sulfide under anaerobic conditions from process solution and (ii) can reduce oxygen under sulfide free conditions. This shuttling capacity is stimulated when SOB are grown under alternating conditions, i.e., "anaerobic-sulfide rich" or "aerobic–sulfide free". This capacity has the potential to maximize recovery efficiency of elemental sulfur.

Given these recent findings, the main objective of the proposal is to investigate and develop novel processing schemes for the operation, monitoring and control of the biological desulfurization process. These schemes should be scalable and controllable. Consequently, a combined experimental and modeling approach is required. On the one hand, process modeling should give a basis for scale-up and control, while on the other hand, experimental work should give proofs of the concept and facilitate model validation.