Bio electrochemical degradation of organosulfur compounds

The treatment of thiols has been challenging for the petrol industry over the past decades. The combustion of natural gas containing thiols (organ sulphur compounds) forms SO2, resulting in adverse health effects, the formation of acid rain and dry acid deposition. Conventional treatment methods focus on the oxidation of thiols. However, this treatment strategies are not widely applied due to low efficiencies and high installation and operational costs. Bio electrochemical systems (BES) have proven themselves capable of treating complex organic materials at high rates and deep treatment of organic pollutants. BES may potentially be used as new removal strategy for the reduction of thiols.

Technological challenge

Bio electrochemical systems are characterized by the separation of oxidation and reduction reactions at the anode and cathode. In these systems at least one of the reactions is bio catalyzed. Electrons flow through an external circuit from the anode to the cathode and reaction rates can be stimulated by changing the electrode potential or current density. Microorganisms can donate electrons to the anode or utilize electrons from the cathode to perform otherwise thermodynamically unfavorable reactions.

Preliminary studies showed that thiols were successfully reduced to sulfide and methane when a small electric current was supplied. During these tests, arbitrarily operating parameters were chosen. To secure a robust technology various aspects need to be evaluated. Currently the involved reaction mechanisms are unknown. The need for cosubstrates, the microorganisms involved, pH and toxicity limits have to be studied. A balance between fast reaction rates and energy efficiency needs to be obtained.

In this study, we will explore the possibility of stimulating anaerobic biodegradation of thiols in BES and its potential to form a safe, low cost and sustainable technology.



Elzinga, M., Liu, D., Klok, J. B., Roman, P., Buisman, C. J., & ter Heijne, A. (2020). Microbial reduction of organosulfur compounds at cathodes in bioelectrochemical systems. Environmental Science and Ecotechnology1, 100009.