Separation of post-fermentation glycerol solution by nanofiltration membrane distillation system

Abstract

The fermentation process generates a broth containing the metabolites, residual substrates and mineral salts. Various unit operations are required for the separation, purification and concentration of organic compounds from the fermentation broth. In this work, nanofiltration (NF) and membrane distillation (MD) were proposed as a method for the preparation of preliminary separated concentrates for a further separation by other processes, such as rectification. The study was carried out using the real broths obtained from the fermentation of glycerol solutions with the Leuconostoc mesenteroides and Citrobacter freundii bacteria. The obtained broths were subjected to the pretreatment by microfiltration, followed by a further separation with NF. The NF270 membrane was used for NF process, and the rejection of citric acid and multivalent ions close to 100% was achieved. The permeate and retentate from NF process were subsequently concentrated about four to five times using membrane distillation. The membrane fouling during the NF and MD processes was observed.