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Abstract: The present study proposes the use of market rejected and waste vegetables as a supplement for improved acetone–ethanol–butanol (ABE) solvent production. In the present study, three different perishable vegetables were evaluated as supplements for ABE fermentation. These vegetables were found to stimulate the solvent production at as low as 1% (w/v) concentration. The supplementation showed improved production of solvents using 4-fold diluted SO2–ethanol–water (SEW) spent liquor supplemented with 25g/l glucose as a substrate. The maximum total solvent production obtained with 5% (w/v) supplementation of carrot, cabbage and tomato was 9.96g/l, 10.49g/l and 10.65g/l, respectively as compared to the control value of 7.43g/l. The applicability of vegetables was successfully evaluated as a complex medium for solvent production. [Copyright &y& Elsevier]

Highlights: [•] Oil palm empty fruit bunches (OPEFB) are fractionated by SO2–ethanol–water mixture. [•] Fractionation of OPEFB feedstock produces cellulosic fibers and spent liquor. [•] Spent liquor contains dissolved hemicellulose sugars (mostly monomers) and lignin. [•] Fractionation and sugar hydrolysis is hindered by the high cation content of OPEFB. [•] Acidic leaching of OPEFB only partly removes cations; more intense deashing needed. [Copyright &y& Elsevier]

The biomass obtained after the extraction of forskolin from the roots of Coleus forskohlii was evaluated as a substrate for the production of acetone-butanol-ethanol (ABE). The spent biomass constituting more than 90% of the raw material showed 50–70% carbohydrates with starch and cellulose being the major constituents. This study was undertaken to optimize enzymatic hydrolysis of C. forskohlii roots for maximum release of fermentable sugars and subsequent fermentation to ABE. The root biomass was hydrolyzed using the Stargen ® 002 and Accellerase ® 1500. Cocktail of both enzymes (16U Stargen ® 002 and 60 FPU Accellerase ® 1500) could produce 41.2 g/l of total reducing sugars (glucose equivalent to 32.33 g/l). The production of ABE was optimized in a batch fermentation using Clostridium acetobutylicum NCIM 2877. The maximum ABE production using the root hydrolysates was 0.55 g/l. Pretreatment with lime and Amberlite XAD-4 increased the production of total solvent to 5.33 g/l. [ABSTRACT FROM AUTHOR]

Highlights: [•] Study suggests the preference of biomass feedstocks appropriate for ABE-fermentation. [•] Effect of varying lignocellulosic sugar concentrations in continuous column reactor. [•] Multi linear regression (MLR) modeling successfully used for continuous production of solvents. [•] Scale up of column reactor is successfully demonstrated. [Copyright &y& Elsevier]