Extraction of phenolic compounds and succinic acid production from spent sulphite liquor

Abstract

BACKGROUND: Spent sulphite liquor (SSL), the by-product stream of the acidic sulphite pulping process, contains fermentable sugars (derived from hemicellulose degradation) and various phenolic compounds.

Detoxification of a Lignocellulosic Waste from a Pulp Mill to Enhance Its Fermentation Prospects

“…Furthermore, these compounds can be recovered from the regenerated solution for valorization purposes. For instance, low molecular phenolics are high-value added by-products with strong antioxidant capacities [23,24]. Therefore, six cycles of regeneration are recommended in this paper.…”

“…The experimental results obtained in this paper together with the fermentation requirements of a specific microorganism permit to establish the detoxification possibilities that might be implemented in different case studies. It should be noted that the study cases represented in Figure 5b belong to hydrolyzates similar to the industrial liquors used in this work such as hardwood hydrolyzates [22,46], softwood hydrolyzates [9,17] and spent sulfite liquors [19,23,35,47]. Main SSL inhibitors can be classified into weak acids, furan derivatives and phenolics among others [48,49].…”

“…In many cases, phenolic compounds are considered the major inhibitors in lignocellulosic hydrolyzates, even more than weak acids and furfurals [32]. This behavior becomes significant when working with bacterial strains for succinic acid production [23], PHA production [52], ABE fermentation [32] or bacterial cellulose [17]. Alexandri et al [23] observed an increase of 62% on succinic acid production when fermenting with two wild-type bacteria strains after SSL organic solvent detoxification which partially removed phenolic compounds.…”

“…This behavior becomes significant when working with bacterial strains for succinic acid production [23], PHA production [52], ABE fermentation [32] or bacterial cellulose [17]. Alexandri et al [23] observed an increase of 62% on succinic acid production when fermenting with two wild-type bacteria strains after SSL organic solvent detoxification which partially removed phenolic compounds. In the case of the SSL phenolics are problematic for fermentation purposes because of the initial concentrations of 12.6 g/L.…”

“…As a result, it was possible to devise an approach for determining the best detoxification technique or combination of techniques suitable in every single case from a technical point of view. In recent years, many publications have studied a single detoxification technique coupled with a specific fermentation scenario [2,9,16,19,23,35]. Other papers have studied the combination of detoxification techniques experimentally [10,17,18,20,21,36,37] or from a theoretical viewpoint [26,31,38,39].…”