Swedish Scientist Presents Biorefinery Seminar at UKZN

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UKZN’s School of Engineering hosted a seminar presented by Sweden’s Dr Adnak Cavka which was the first in a biorefinery series.

Cavka, currently a post-doctoral researcher in a group headed by Professor Leif Jonsson at Umea University in Sweden, was invited by Professor Anne Stark of the SMRI Sugarcane Biorefinery Research Chair.

His talk, titled: “Biorefining of Lignocellulose - Detoxification, On-site Enzyme Production and Thecno-Economic Evaluation”, dealt with a new approach to achieve efficient detoxification of inhibitory lignocellulosic slurries and hydrolysates using reducing agents, such as sodium dithionite, sodium sulfite and sodium borohydride.

Results from laboratory and demonstration scale experiments indicate that additions of as low as 10-15 mM of reducing agents may considerably improve the fermentability of lignocellulosic hydrolysates, even under mild reaction conditions (20- 25oC, pH 5.5-6.0, and 5-10 min.). Improvements in fermentability achieved with reducing agents under these conditions are similar to those achieved with more complex alkali detoxification methods (55oC, pH 9.0, and 3h).

The possibility of producing enzyme on-site as co-products with production of biofuels using recombinant Aspergillus niger and low-value residual streams, such as stillage, was also presented and discussed. Experimental results showed that fermentations performed with nutrient-poor industrial stillages from processes based on waste fibre sludge yielded similar xylanase and cellulase activities as fermentations performed with nutrient–rich synthetic media (10% glucose).  Results from a techno-economic evaluation performed on the above described detoxification methods were also presented with emphasis on lower yeast and enzymes loads, as well as its impact on operating costs and capital expenditure.

Cavka holds a PhD in technical chemistry as well as an MSc in analytical chemistry, an MBA in management and an MSc in business and economics.  He was one of 10 PhD candidates selected and trained in an industrial executive programme at Umea University.  His project was funded by SEKAB E-Technology, and performed in close collaboration with the forest biorefinery in Ornskoldsvik, Sweden.