Research School for Socio-Economic and
Natural Sciences of the Environment
Research School for Socio-Economic and
Natural Sciences of the Environment

Mark Roghair

Date: 16 November 2018
Time: 16:00 - 17:30
Location: Aula, building 362, Gen. Foulkesweg 1, Wageningen

Dissertation title: 

Control strategies for ethanol-based chain elongation processes

Group: Wageningen University, Environmental Technology
Promotors: C.J.N. Buisman
Copromotors: D.P.B.T.B. Strik and dr. R.A. Weusthuis

Extra information:


Chain elongation is an open-culture fermentation process that facilitates conversion of organic residues with an additional electron donor, such as ethanol, into valuable n-caproate. Open-culture processes are catalyzed by a consortium of microorganisms which typically also bring undesired (competing) processes. Inhibition of competing processes, such as excessive ethanol oxidation (EEO), will lead to a more efficient chain elongation process. In this thesis, we show that EEO is dependent on hydrogenotrophic methanogenesis and that the overall reaction can be referred to as syntrophic ethanol oxidation. The rate of syntrophic ethanol oxidation was found to be limited (i.e. controlled) by the CO2 availability in the reactor and also at high n-caproate concentrations. Although chain elongation can effectively produce n-caproate from organic residues, ethanol and base use need to be further reduced to lower the operational costs and environmental impact.

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