Process intensification of biofuel production
Lead Research Organisation:
Loughborough University
Department Name: Chemical Engineering
Abstract
The main objective of this project is to investigate the continuous extraction capabilities of microbubbles in a fermentation reactor operated at 60-65C, to improve cellulosic biofuel production. One of the main issues pertaining to fermentation of sugars to alcohol is the decline in performance of fermentative organisms at high product concentrations, due to the inhibitory effects of the product on the producing organism. This is particularly true with thermophilic bacteria which grow at relatively high temperatures (50-70C). However, some of these bacteria are particularly well suited to growth on renewable, lignocellulosic feedstocks, so an effective way to continuously remove the alcohol from the fermentation broth would make the lignocellulose to ethanol process more economic. When using a gas to strip alcohol from a liquid, the most important feature for determining the mass transfer rate is the ratio of bubble surface area to volume. For the same volume of gas, smaller bubbles will have a higher surface area than larger bubbles and should therefore be more effective at stripping ethanol from a solution. However, smaller bubbles could potentially be more damaging to the bacteria, so their overall benefits cannot be assumed. In this PhD project we will develop a reactor/stripping unit to allow continuous extraction of ethanol using microbubbles and develop a mathematical model to predict performance.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509516/1 | 01/10/2016 | 30/09/2021 | |||
| 1808885 | Studentship | EP/N509516/1 | 01/10/2016 | 21/04/2020 | Joseph Calverley |
| Description | Using air to partially evaporation liquids, in order to increase their concentration in the liquid phase or to recover vapour at a higher concentration, is a mature subject but with some important knowledge gaps. Recently, by using bubbles with diameters in the range of 50-200 um, it has been shown that the stripping quality can go beyond what would be expected using a conventional bubble size distribution. This project has demonstrated this effect in the application of bioethanol production at elevated temperatures, as so called thermophilic microorganisms often have the ability to ferment a broad range of sugars, such as those which are produced during the pretreatment of cellulose, which as a biofuel feedstock does not compete with food for land use because it makes up much of the waste material produced during food farming. This project simulates continuous style experiments which show that ethanol concentrations can be maintained in a liquid below the levels to which they would be harmful the fermenting organism, which is a significant discovery as these microorganisms often suffer from severe ethanol inhibition. Additionally, work has been undertaken which demonstrates the role the gas temperature plays on the evaporation, which is normally neglected in favour of the the liquid temperature as normally these processes are effectively at thermal equilibrium. |
| Exploitation Route | While this project has focused on a single example of a thermophilic organism with which to demonstrate in-situ continuous ethanol recovery from a fermenter, there are a large number of available alternatives which suffer from extreme ethanol inhibition. Therefore, these could be used with this technology to provide energy efficient and financially viable ethanol production facilities which benefit from the increased ethanol production rate at higher temperatures, which allow some fermenting organisms to use non-traditional feedstocks such as cellulosic food wastes. Additionally, there is no reason to think that other volatile biofuels could not be recovered in the same way. It would be of interest to see the quality of butanol extraction, for example. |
| Sectors | Energy,Environment |
| URL | https://www.lboro.ac.uk/departments/chemical/news/2018/a-step-towards-cellulosic-biofuel-production-.html |
| Description | During this project, a working partnership with an industrial partner has evolved. This has involved us working cooperatively on a project, along with another university, to bring together the different technologies in which we specialise (microbubble stripping from Loughborough, thermophilic fermentation from the university partner and lab scale microbubble generation from the industrial partner) to simulate a full lab-scale continuous thermophilic fermentation with in-situ ethanol recovery. This builds on previous work where the fermentation was simulated by adding the fermentation products into a microbubble stripping process. |
| First Year Of Impact | 2018 |
| Sector | Energy,Environment |
| Impact Types | Economic |