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DEVELOPMENT OF HIGH RATE, LOW ENERGY INPUT BIO REACTOR FOR ETHANOL PRODUCTION

Objective

THE AIM OF THIS R&D WORK ARE TO DEVELOP A NEW HIGH RATE ETHANOL FERMENTER AND TO APPLY THIS TECHNOLOGY TO NOVEL ETHANOL FERMENTINGORGANISMS IN ORDER TO IMPROVE ETHANOL THE YIELD AND PRODUCTIVITY. THE DEVELOPMENT OF THE NOVEL BIOREACTOR WILL CONTINUE THE PRELIMINARY STUDIES PREVIOUSLY CARRIED OUT BY THE TWO INSTITUTES, SHOWING THAT A SIGNIFICANT IMPROVEMENT IN THE ETHANOL PRODUCTIVITY COULD BE OBTAINED WHEN USING PACKED BED REACTORS AND CONVENTIONAL PACKING MATERIAL AS COMPARED TO BATCH FERMENTATION. THE PERFORMANCE WAS FURTHERMORE CONSIDERABLY IMPROVED WHEN USING NOVEL REACTOR PACKING. FERMENTATION TIMES BELOW 1HR WAS ACHIEVED WITH 150 G/L GLUCOSE.
THE LONG TERM STABILITY OF THE PROCESS WAS HOWEVER HOWER, WITH A DECREASE IN ETHANOL PRODUCTIVITY AFTER 50 DAYS OF RUNNING. SUCH A DECREASE WAS NOT NOTICED IN THE FERMENTER WITH THE LOWER PRODUCTION RATE. THE WORK UNDER THIS PROJECT WILL BE DIVIDED INTO THREE RELATED PARTS, COVERING RESEARCH INTO ENGINEERING ORIENTATED PROBLEMS OF THE FERMENTER; THE APPLICATION OF THIS FERMENTER TECHNOLOGY TO NOVEL FERMENTATIONS; AND THE MICROBIOLOGY OF THESE FERMENTATIONS.

PILOT PLANT EXPERIMENTS WILL BE CARRIED OUT AT IRCHA RESEARCHING THE ENGINEERING ASPECTS OF THE REACTOR. THE EXPERIMENTS WILL INVESTIGATE THE EFFECT OF PACKING DENSITY AND REACTOR GEOMETRY ON THE PERFORMANCE AND LONG TERM STABILITY OF THE PROCESS. USING THE NOVEL PACKING MATERIAL OF POLYESTER FIBER PREVIOUSLY FOUND TO BE HIGHLY SUITABLE, THE R&D WORK WILL INITIALLY BE TO OPTIMISE THE ETHANOL PRODUCTION RATE AND YIELD AS WELL AS THE SUGAR UTILISATION. HAVING OBTAINED THESE GOALS, THE PROBLEMS OF LONG TERM STABILITY WILL BE INVESTIGATED. THE WORK WILL BE CARRIED OUT ON THE PILOT PLANT SCALE, USING ONE 50-100 LITER FERMENTER, A SYNTHETIC NONSTERILE SUCROSE BASED MEDIUM, AND TRADITIONAL OPERATING CONDITIONS. WORK AT STRATHCLYDE UNIVERSITY WILL BE CARRIED OUT AT THE LABORATORY SCALE. IT WILL CONCENTRATE ON THE APPLICATION OF THIS FERMENTER TECHNOLOGY TO THE NOVEL YEAST PACHYSOLEN TANNOPHILUS. THIS YEAST WILL FERMENT PENTOSES DERIVED FROM HEMI-CELLULOSE TO ETHANOL. PREVIOUS WORK HAS INDICATED THAT HIS ORGANISMS WILL FERMENT, BUT NOT GROW, ON XYLOSE UNDER ANAEROBIC CONDITIONS. HOWEVER EVEN UNDER MICROAEROBIC CONDITIONS, EXCEPTIONALLY LONG FERMENTATION TIMES ARE REQUIRED, UP TO 7 DAYS IF USING SOFT-WOOD HYDROLYSATE. THE APPLICATION OF PACKED BED TECHNOLOGY SHOULD HAVE THE POTENTIAL TO REDUCE THIS CONSIDERABLY IF DIRECT COMPARISON WITH GLUCOSE OR MOLASSES FERMENTATIONS CAN BE MADE. THE R&D WORK WILL THEREFORE BE TO INVESTIGATE THE APPLICATION OF SUCH REACTORS TO THIS FERMENTATION. INITIAL WORK WILL BE CARRIED OUT ON DEFINED XYLOSE MEDIA, INVESTIGATING THE EFFECT OF LIQUID RESIDENCE TIME, FERMENTATION TEMPERATURE AND MEDIUM PH, AND PACKING DENSITY, USING A PRE-SELECTED STRAIN OF THE YEAST. HAVING IDENTIFIED THE BEST OPERATING CONDITIONS, EXPERIMENTS WILL BE CARRIED OUT USING SYNTHETIC SOFT-WOOD HEMICELLULOSE HYDROLYSATE, TO ESTABLISH OPERATING PERFORMANCE ON MIXED SUGAR MEDIUM AND WHEN SOME OF THE GROWTH INHIBITORS OF WOOD HYDROLYSATE ARE PRESENT. A SECONDARY AIM WILL BE TO INVESTIGATE THE VIABILITY OF THE YEAST UNDER PROLONGED ANAEROBIC CONDITIONS, AND TO SEE IF ANY LOSS OF VIABILITY CAN BE RECOVERED BY THE ADDITION OF OXYGEN.

RESEARCH ON IRCHA ON THE SECOND AIM WILL BE CONCENTRATED ON THE BACTERIA ZYMONAS MOBILIS AND SUCROSE FERMENTATIONS. INITIAL WORK WILL BE ON SCREENING THE ORGANISM, TO OBTAIN THE BEST STRAIN, AND TO OPTIMISE THE MEDIUM TO OBTAIN HIGH ETHANOL YIELD AND PRODUCTIVITY. THE INITIAL WORK WILL BE CARRIED OUT IN FERMENTERS. THE WORK WILL BE FOLLOWED BY A STUDY OF THE FERMENTATION USING A CONTINUOUS FERMENTER SYSTEM BASED ON THE NOVEL BIOREACTOR DEVELOPED IN THE MAIN PART OF THE PROGRAM. DURING THIS WORK COMPARATIVE FERMENTATIONS WILL BE CARRIED OUT USING BATCH AND CONTINUOUS FERMENTERS. A SEARCH FOR MORE EFFICIENT STRAINS OF THE ORGANISM WILL CONTINUE THROUGHOUT THE PROJECT IN COLLABORATION WITH PROF J BARATTI OF CNRS MARSEILLE.
THE TIME SCHEDULE FOR THIS WORK IS THREE YEARS, WITH THE THREE INTEGRAL PARTS OF THE PROGRAM WORKING IN PARALLEL.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Institut National de Recherche Chimique Appliquée
Address

91710 Vert-le-petit
France

Participants (1)

UNIVERSITY OF STRATHCLYDE
United Kingdom
Address

G1 1XQ Glasgow