ISCF WAVE 1 IB Process intensification of cellulosic biofuel production using continuous product extraction with microbubble technology
Lead Research Organisation:
University of Bath
Department Name: Biology and Biochemistry
Abstract
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Technical Summary
Perlemax has developed and patented the concept of microbubble generation by virtue of fluidic oscillation which has advantages over current methods of microbubble generation due to its very low power input. This opens up the field of microbubble technology to a much wider range of applications, including addressing processes where mass-transfer is a limitation. We intend to address the issue of ethanol removal from thermophilic (60-65C) fermentation broths to improve cellulosic biofuel production. Batch production of bioethanol by the thermophilic bacterium Geobacillus thermoglucosidasius is limited by moderate (cf yeast) concentrations of bio-ethanol which significantly limits the possibility for process intensification and volumetric productivity. This can be improved by gas-stripping but the volumetric throughput of gas using normal sparger aeration would be impractical in a commercial process. As a practical and economic solution to this problem we will continuously extract fermentation products from the bioreactor by using pre-heated microbubbles using the Perlemax energy efficient microbubble generation technique. Availability of high interfacial area for mass transfer and intense internal mixing within the microbubbles will be key features in this approach.
While the rationale for the approach should be self-evident, the effect of microbubbles on the production organisms needs to be established. Microbubbles could potentially damage bacteria when rupturing at the top of the reactor. Therefore, after an initial optimisation using simulated broths, to establish the useful operating range, we will investigate the physiology of bacteria during experiments and adjust the operating parameters to find the most suitable conditions. Additionally, we will develop a computational model to assist scaling up the process and assess economic viability.
While the rationale for the approach should be self-evident, the effect of microbubbles on the production organisms needs to be established. Microbubbles could potentially damage bacteria when rupturing at the top of the reactor. Therefore, after an initial optimisation using simulated broths, to establish the useful operating range, we will investigate the physiology of bacteria during experiments and adjust the operating parameters to find the most suitable conditions. Additionally, we will develop a computational model to assist scaling up the process and assess economic viability.
Planned Impact
As described in proposal submitted to TSB
Organisations
People |
ORCID iD |
| David Jonathan Leak (Principal Investigator) |
Publications
Calverley J
(2021)
Continuous removal of ethanol from dilute ethanol-water mixtures using hot microbubbles.
in Chemical engineering journal (Lausanne, Switzerland : 1996)
Calverley J
(2020)
Hot Microbubble Air Stripping of Dilute Ethanol-Water Mixtures
in Industrial & Engineering Chemistry Research
Wright A
(2018)
Dielectric barrier discharge plasma microbubble reactor for pretreatment of lignocellulosic biomass.
in AIChE journal. American Institute of Chemical Engineers
| Description | The project aimed to establish that microbubble extraction can be used to strip ethanol from a bioreactor such that the ethanol concentrations in the reactor can be maintained at sub-toxic levels. Initial we showed using ex-situ studies that a) the principle on which this is based works in practice and it is possible to strip ethanol continuously from a stream at 10% v/v ethanol and maintain an output of <1% v/v at steady state, b) that cells of Parageobacillus thermoglucosidasius can tolerate the stripping conditions used and c) ethanol produced in a bioreactor at a nominal 6% (v/v), which exceeds toxic levels, can be stripped from the culture in an ex-situ (recirculating) device. Subsequently (and with considerable "inventiveness") we combined the two and managed to show that we could grow P thermoglucosidasius under continuous culture conditions that would generate a nominal 7%(v/v) ethanol but maintain the culture concentration at less that 2%(v/v) which is sub-toxic. The additional ethanol was stripped in the gas stream at practical gas flow rates. If replicated at a large scale this is consistent with commercial production. |
| Exploitation Route | This has the potential for commercial exploitation |
| Sectors | Energy Manufacturing including Industrial Biotechology |