Industrial cheese whey processing comprises the isolation of proteins and lactose, but the residual delactosed whey permeate (DWP) still contains 10 % lactose of the original content. Additional valorization is difficult though, because the high salt concentration in DWP inhibits the metabolism of yeast, which convert the remaining lactose to valuable bioethanol.
Christopher Wagner, Leibniz University, Hanover, Germany, and colleagues tested three different methods to lower salt content in DWP: simple dilution, nanofiltration, and electrodialysis. Dilution is the easiest and cheapest way to reach ethanol concentrations of > 6.5 % alcohol by volume (AbV) which are suitable for subsequent distillation. Nanofiltration and electrodialysis lead to shorter fermentation times and higher concentrations of > 8 % AbV and > 10 % AbV, respectively. Unfortunately, both methods are very expensive and only difficult to include into an industrial process.
Overall, desalination enhances ethanol production from DWP but the researchers suggest an alternative optimization strategy by redesigning the whole process from milk to DWP with an earlier desalination step.
- Enhancing bioethanol production from delactosed whey permeate by upstream desalination techniques,
Christopher Wagner, Christian Benecke, Heinrich Buchholz, Sascha Beutel,
Engineering in Life Sciences 2014.