Membrane filtration of spent sulfite liquor model compounds as an upstream process for fermentation
Sprache des Vortragstitels:
Minisymposium der Verfahrenstechnik 2019
Sprache des Tagungstitel:
Spent sulfite liquor (SSL) is a valuable byproduct stream of wood pulping processes. Depending on the wood type, pulping method and process parameters, different compositions of SSL are produced. In pulping mills the SSL is usually thickened by evaporation and burned in the recovery boiler to produce energy and to recover pulping chemicals.
A partial material use of SSL leads to higher process efficiency in terms of bio-refinery. For beech wood derived SSL, highly efficient concepts for isolation of various compounds (e.g. acetic acid, furfural) are already implemented. Using other types of wood, the composition of the SSL changes significantly and therefore, other concepts for downstream processing are necessary. Membrane processes (e.g. ultrafiltration and nanofiltration) show promising results in different separation steps during this downstream processing .
A promising way of utilization of SSL derived sugars (such as mannose, glucose and xylose) in a consecutive conversion process is the production of platform chemicals. Beside different types of sugars and aldonic acids, lignosulphonates, acetic acid, furfural and hydroxyl methyl furfural (HMF) are the main compounds of the softwood SSL. Especially acetic acid, furfural and HMF are well known as fermentation inhibitors for many microorganisms . A membrane separation process should separate sugars from inhibitors enabling a subsequent metabolization by microorganisms.