Restructuring the Conventional Sugar Beet Industry into a Novel Biorefinery: Fractionation and Bioconversion of Sugar Beet Pulp into Succinic Acid and Value-Added Coproducts

Abstract

Sustainable chemical production should rely on the valorization of crude renewable resources. Waste biomass refining complies with bioeconomy and circular economy initiatives. In this regard, sugar beet pulp (SBP) was efficiently fractionated into pectins, phenolic compounds, and a sugar-rich hydrolysate that was subsequently used as fermentation feedstock for succinic acid production. Phenolic compounds were separated via acidified aqueous ethanol extraction, while pectins were obtained via sequential treatment with HCl, NH3·H2O and ethanol. Hydrolysis of cellulose and hemicellulose was optimized in laboratory and pilot scales leading to 45 g/L of total sugars with glucose and arabinose being the predominant ones. Laboratory-scale fed-batch fermentations were carried out with the bacterial strain Actinobacillus succinogenes cultivated on SBP hydrolysate resulting in the production of 30 g/L of succinic acid concentration with productivity of 0.62 g/L/h and yield of 0.8 g/g. Similar fermentation efficiency was also demonstrated in 50 L bioreactor cultures. Succinic acid crystals were purified from the fermentation broth by two alternative downstream separation processes on the basis of either semipilot scale bipolar membrane electrodialysis with product purity and yield of 79% and 21.2% or acidification of succinate salts using cation exchange resins with product purity and yield of 95% and 80.1%, respectively. The novel biorefinery concept led to 78.6 g of phenolic-rich extract, 303.1 g of a pectin-rich isolate, 268 g of succinic acid, and 208.4 g of remaining solids with 20% protein content from 1 kg of SBP.

Evaluation of organic fractions of municipal solid waste as renewable feedstock for succinic acid production

“…The experimental succinic acid crystal purity achieved in this study using the fermentation broth derived from OFMSW-based cultures was more than 99%. Individual DSP stages resulted in similar mass balances to the ones reported by Alexandri et al [50]. The UniSim software was used for the estimation of mass and energy balances to design and simulate the whole bioprocess.…”

“…The total number of bioreactors required per batch cycle, the volume of each bioreactor and the minimum bioreactor cost were estimated based on the study of Koutinas et al [49] and Dheskali et al [41] using the optimal succinic acid production efficiencies in batch and continuous cultures. The DSP used in this study has been presented by Alexandri et al [50]. The experimental succinic acid crystal purity achieved in this study using the fermentation broth derived from OFMSW-based cultures was more than 99%.…”

“…The effect of initial sugar concentration (30,50, 80 g/L) was evaluated in batch fermentations using both OFMSW hydrolysate and synthetic medium containing commercial carbon sources in a similar ratio (sucrose 4.3%, glucose 73.2%, fructose 18.4%, mannose 0.9%, arabinose 1.8%, galactose 0.3% and glycerol 1.2%) as the one contained on average in OFMSW hydrolysate. The latter medium was used as control experiment.…”

Valorising Agro-industrial Wastes within the Circular Bioeconomy Concept: the Case of Defatted Rice Bran with Emphasis on Bioconversion Strategies

“…Various acids (organic and inorganic) have been proposed in the literature, such as sulphuric acid, hydrochloric acid, phosphoric acid, and citric acid, as efficient means for hemicellulose solubilisation [33]. Dilute sulphuric acid hydrolysis has been successfully employed in a variety of biomasses, including sugar beet pulp [34], coffee pulp and coffee mucilage [35,36] among others. The main disadvantage of this method is the production of inhibitory compounds (acetic acid, furfural, 5-hydrolxymethylfurfural (HMF)) that could hamper the fermentability of the produced hydrolysate.…”

Two-Stage Crystallization Combining Direct Succinimide Synthesis for the Recovery of Succinic Acid From Fermentation Broth

“…Succinic acid is an important renewable four-carbon building block chemical that is prevalent in humans, animals, plants, and microorganisms (Li et al, 2010;Alexandri et al, 2019). Succinic acid has been widely used in medicine, food, the chemical industry, and agriculture (Delhomme et al, 2009).…”