High solid fed‐batch butanol fermentation with simultaneous product recovery: Part II—process integration

Abstract

In these studies, liquid hot water (LHW) pretreated and enzymatically hydrolyzed Sweet Sorghum Bagasse (SSB) hydrolyzates were fermented in a fed-batch reactor. As reported in the preceding paper, the culture was not able to ferment the hydrolyzate I in a batch process due to presence of high level of toxic chemicals, in particular acetic acid released from SSB during the hydrolytic process. To be able to ferment the hydrolyzate I obtained from 250 g L SSB hydrolysis, a fed-batch reactor with in situ butanol recovery was devised. The process was started with the hydrolyzate II and when good cell growth and vigorous fermentation were observed, the hydrolyzate I was slowly fed to the reactor. In this manner the culture was able to ferment all the sugars present in both the hydrolyzates to acetone butanol ethanol (ABE). In a control batch reactor in which ABE was produced from glucose, ABE productivity and yield of 0.42 g L h and 0.36 were obtained, respectively. In the fed-batch reactor fed with SSB hydrolyzates, these productivity and yield values were 0.44 g L h and 0.45, respectively. ABE yield in the integrated system was high due to utilization of acetic acid to convert to ABE. In summary we were able to utilize both the hydrolyzates obtained from LHW pretreated and enzymatically hydrolyzed SSB (250 g L ) and convert them to ABE. Complete fermentation was possible due to simultaneous recovery of ABE by vacuum. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:967-972, 2018.

Production of acetone–butanol–ethanol (ABE) from concentrated yellow top presscake using Clostridium beijerinckii P260

“…However, that was not the case. These fermentation times were comparable to the control fermentation where glucose was used as substrate . In all three YT fermentations, approximately 96–97% conversions were obtained.…”

“…The experiment resulted in a productivity of 0.49 g L −1 h −1 . This productivity is higher than the productivity obtained in glucose‐based control fermentation (0.42 g L −1 h −1 ) . In this experiment, the highest cell concentration was 1.00 g L −1 at 24 h, after which it declined (Fig.…”

“…This suggested that cell growth inhibition occurred. However, the culture was still able to produce 20.20 g L −1 ABE, which is higher than obtained in glucose fermentation …”

“…A). A control fermentation, where 60 g L −1 glucose was used, resulted in a productivity of 0.42 g L −1 h −1 . The productivity obtained at 125 g L −1 YT is 67% higher than that of the control experiment.…”

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

“…Neither of the hydrolyzates (Process C) were fermented successfully. It is suggested that acetate be removed from the hydrolyzates prior to fermentation by adsorption or a fed batch system be used to ferment both the hydrolyzates as in the following paper . We have achieved the objectives as outlined in the introduction section of this article.…”