Research Project Summary Information
Microporous Ceramic Composite Membrane for Biofuels Production(ST10229-1)
The Hilliard Corporation
Many biorefinery processes have a fermentation step followed by separation of the microbes from the broth. High speed stainless steel centrifuges are often used for separation, but they are expensive, complex, and energy intensive. Tangential flow filtration devices are an alternative, but the polymeric membranes used in them often have a limited lifespan, are sensitive to harsh chemicals, and are damaged by grit and steam sterilization. Corning has developed a durable ceramic composite membrane that is marketed in other filtration applications, but has not been tested in fermentation settings. Corning has partnered with Hilliard, engineers and manufacturers of filtration devices, using Corning membranes.
1) study two microbes and two biorefinery processes: ethanol from 5-carbon sugars and polyhydroxyalkanoates from 5-carbon sugars, each using specific microbes
2) design and demonstrate the process at two scales: 10 liter and 400 liter
3) measure energy consumption of filtration, while varying transmembrane pressure and shear rate (velocity) across the membrane surface
4) measure energy consumption of a typical centrifuge
5) compare energy consumption results of the membrane and centrifuge with those expected from a polymeric membrane
6) evaluate performance, manufacturing cost, and energy savings, and
7) provide recommendations as to the suitability and economic competitiveness of the system.
This study demonstrated the usefulness of the Hilliard filtration system with Corning filter elements in the separation of cells from fermentation broth. The market for fermentation separation systems is more than $100 million/year in the US, and $250 million worldwide. A 10% market share of the US market, assuming 20% profit, would allow the firms to hire 20-30 workers. Other New York State firms that separate cells from broth would benefit as well. It is hoped that the results will attract potential customers with specific fermentation broth testing needs.
The energy consumed per unit volume of supernatant/permeate was compared to centrifugation and to a polymeric membrane system. The Hilliard system was comparable to a decanter bowl centrifuge, but less efficient than several other types of centrifuges. The system was also much less efficient than a competing brand’s tangential flow system, likely because the other system had a variable speed pump, but the Hilliard system had a large fixed speed pump that consumed energy at a constant rate regardless of the permeate flow rate. Further testing with a variable speed pump is needed.
The energy efficiency of the system was directly proportional to the permeate flow rate. Although energy usage is an important metric for comparing separation technologies, there are tradeoffs. For example, the product of ethanol fermentation is extracellular. Removing all of the cells with a membrane avoids fouling the downstream distillation system. On the other hand, recombinant proteins produced in E. coli are intracellular, and it is less important if some cells remain, so centrifugation may be used. In general, centrifugation concentrates the cell suspension more than tangential flow filtration systems, so centrifugation is advantageous when cells need drying. Other considerations include the higher capital cost of centrifuges, the higher consumable costs for filtration membrane replacement, and the relative ease of scale-up of filtration systems compared to centrifuges.
The Hilliard Corporation
100 W 4th St
Elmira, NY 14901
SUNY Upstate Medical University
SUNY College of Environmental Science an
NYSERDA Contact Information
R&D - Environment & Energy Res