Butanol production from sweet sorghum bagasse with high solids content: Part I—comparison of liquid hot water pretreatment with dilute sulfuric acid

Abstract

In these studies, we pretreated sweet sorghum bagasse (SSB) using liquid hot water (LHW) or dilute H SO (2 g L ) at 190°C for zero min (as soon as temperature reached 190°C, cooling was started) to reduce generation of sugar degradation fermentation inhibiting products such as furfural and hydroxymethyl furfural (HMF). The solids loading were 250-300 g L . This was followed by enzymatic hydrolysis. After hydrolysis, 89.0 g L sugars, 7.60 g L acetic acid, 0.33 g L furfural, and 0.07 g L HMF were released. This pretreatment and hydrolysis resulted in the release of 57.9% sugars. This was followed by second hydrolysis of the fibrous biomass which resulted in the release of 43.64 g L additional sugars, 2.40 g L acetic acid, zero g L furfural, and zero g L HMF. In both the hydrolyzates, 86.3% sugars present in SSB were released. Fermentation of the hydrolyzate I resulted in poor acetone-butanol-ethanol (ABE) fermentation. However, fermentation of the hydrolyzate II was successful and produced 13.43 g L ABE of which butanol was the main product. Use of 2 g L H SO as a pretreatment medium followed by enzymatic hydrolysis resulted in the release of 100.6-93.8% (w/w) sugars from 250 to 300 g L SSB, respectively. LHW or dilute H SO were used to economize production of cellulosic sugars from SSB. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:960-966, 2018.

Yellow top (Physaria fendleri) presscake: A novel substrate for butanol production and reduction in environmental pollution

“…The culture could not use all the glucose because it reached butanol/ABE tolerance level. In this fermentation, a productivity of 0.42 gL −1 h −1 and an ABE yield of 0.36 were achieved …”

“…The possible reasons for poor fermentation were either lack of nutrients or lack of sugars in the medium. Control fermentation experiment with glucose and same amount of nutrients suggested that there was no lack of nutrients thus leaving behind the only option of sugar limitation, which further strengthened (see below paragraph) that the culture was not able to hydrolyze the Yellow Top presscake without pretreatment.…”

“…Acetone, butanol, ethanol, acetic acid, and butyric acid were measured by GC chromatography as described elsewhere . Sugars were estimated using HPLC (Agilent Technologies, Santa Clara, CA) equipped with a refractive index detector and an auto sampler.…”

“…Cost of the feedstocks is of high importance and for that reason economically available agriculturally based feedstocks including cellulosic biomass (e.g., wheat straw, barley straw, corn stover, switchgrass, miscanthus, dry distillers grains and solubles, sweet sorghum bagasse, sugarcane bagasse, and so forth) should be used. As compared to corn ($158 ton −1 ), cost of these feedstocks is expected to be much lower ($24–58 ton −1 ) . Furthermore, we investigated the use of zero‐cost substrates such as food waste, orchard waste including apple pomace, pear drops, and starch‐based packing peanuts .…”

Global View of Biofuel Butanol and Economics of Its Production by Fermentation from Sweet Sorghum Bagasse, Food Waste, and Yellow Top Presscake: Application of Novel Technologies

“…In previous studies, we investigated the use of SSB, food waste, and YTP to produce bio-butanol [12,29,31]. However, it is important to consider additional factors such as the costs of enzymes, plant size, and consumption of steam and cooling water, all of which affect the cost of producing butanol from the SSB, FW, and YTP.…”