Processing techniques which can be rather costly have hindered the growth of second generation biofuels as first generation feedstock deriving from sugarcane and corn are cheaper to create. Swiss scientists have developed a method for streamlining biofuel production using chemical engineering to consolidate fundamental stages in the production chain.
One way to make the process more cost effective is the integration of several process steps into one step (called consolidated bioprocessing), ideally combined with the elimination of washing and detoxification steps. This molecular biology approach involves the engineering of one superior genetically modified microorganism that is able to produce the hydrolytic enzymes as well as ferment the derived sugars into ethanol. Though undoubtedly a highly attractive approach, it is still an open question whether such a highly engineered organism could withstand the rigours of a large-scale industrial process. Furthermore, the use of such biocatalysts might lead to considerable disposal costs.
Bern University of Applied Sciences (BFH-HAFL) in Zollikofen Dr. Michael Studer and his team at the Swiss Federal Institute of Technology (ETH) are developing a consolidated bioprocessing technique using a mixture of robust industrial microbial strains growing in one reactor. A special membrane reactor was developed to counter varying oxygen requirements, where the researchers layered the involved groups of microorganisms in a biofilm atop each other, creating a reactor in which both catalysts function simultaneously. Studer said, “Yields are around 80% if we’re converting pure cellulose into ethanol. Using pre-treated, non-detoxified wheat straw as a raw material, the yield is only slightly lower – around 70%.”
The researchers anticipate that the new process will be compatible with existing facilities, and could be realized using new modules that conveniently function within current infrastructures. Within three to five years, the team aims to establish an industrial pilot to assess its practical merits.
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