Aalborg Universitet

Butyric acid fermentation with in-situ products separation

Baroi, George Nabin; Skiadas, Ioannis; Westermann, Peter; Gavala, Hariklia N.

Publication date:2014

Document VersionAccepted author manuscript, peer reviewed version

Link to publication from Aalborg University

Citation for published version (APA):Baroi, G. N., Skiadas, I., Westermann, P., & Gavala, H. N. (2014). Butyric acid fermentation with in-situ productsseparation. Poster presented at Tomorrow’s biorefineries in Europe, Brussels, Belgium.

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Butyric acid fermentation with in-situ products separation

Baroi G.N 1, Skiadas I.V. 1, Westermann P. 1, Gavala H.N1. 1Aalborg University Copenhagen (AAU-Cph), Department of Biotechnology, Chemistry and Environmental Engineering, A C Meyers Vænge 15, DK 2450 Copenhagen SV Denmark.

Background Butyric acid and its esters are used as food supplements, as artificial flavours, as solvent and even its potential beneficial effects in intestinal and extra intestinal diseases and sickle cell disease have been reported. Another potential use of butyric acid is to produce butanol via catalytic hydrogenation. The demand of the butyric acid is approximately 50,000 ton/year. The main bottlenecks of commercialization of biological production of acids ( in overall) are: (1) utilization of cheap feed stocks (2) Proper strain selection &/or improvement (3) Process development for higher productivity (4) Downstream processing The first three aspects were successfully considered for biological butyric acid production from pretreated and hydrolysed wheat straw (PHWS) by C.tyrobutyricum. Continuous fermentation and in-situ separation of butyric acid increased C6 and C5 consumption and butyric acid production rates compared to batch fermentation without in-situ products removal. The process efficiency was verified in pilot-scale as well. However, further improvement of downstream process required.

Acknowledgement

The authors wish to thank the Commission of the European Communities for the financial support of this work under SUPRABIO project (FP7-cooperationproject no 241640).

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glucose xylose butyric acid acetic acid

Rat

e (

g/d

ay)

Remain in the fermentor

Product extracted by REED

metabolized

Acid from Feedflow extracted by REED

In-s

itu

pro

du

ct

sep

arat

ion

at

Pilo

t sc

ale

(20

L)

Pretreatment Enzymatic hydrolysis

Strain selection and development

Process development

In-situ product separation at lab scale

(3L)

Process model of butyric acid production from wheat straw

Conclusion • Fermentation coupled with REED in-situ separation of PHWS with the adapted C. tyrobutyricum gave a higher

(28 to 58%) butyric acid yield compared to synthetic medium fermentation. • Continuous fermentation exhibited much higher (>600% for 60% PHWS) sugars consumption rates compared

to batch fermentations • With REED in-situ acid seperation results higher sugars consumption rate and C4 production rates (> 46%) • Fermentation coupled with REED in-situ separation of 100% PHWS continued unhindered with just urea and

K2HPO4 added reaching a productivity of 1,31 g/l/h butyric acid production and 97% sugars utilization

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60% 70% 80% 100% 60%

With REED Without REED

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pro

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ate

(g

/L/h

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Glucose Xylose Acetic acid Butyric acid Hydrogen

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DL

ED

Eff.

REED Membrane Reactor

Infl = Inflow; Eff.= Effluent ;ED = Electrolyte; DL= Dyalyzate

Schematic diagram of the experimental setup Rates of synthetic medium ( mixed glucose and xylose) based fermentation with and without in-situ acids separation by REED at HRT 1 day

Rates of PHWS based fermentation with and without in-situ acids separation by REED at HRT 1 day

Continuous fermenation of 100% PHWS with REED

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A B C

With REED Without REEDCo

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ate

(g

/L/h

)

Glucose Xylose Acetic acid Butyric acid Hydrogen

Glucose and Xylose concentrations (g/L) for A (38 , 22), B (54, 34) and C (38, 22)

% (v/v) PHWS in a medium with

Re

sult

s