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Team:Alberta/HumanPractices/Bioreactor
From 2011.igem.org
Bioreactor Design
At the outset of our project, Team Alberta possessed a vision of communities having the ability to utilize our created fuel for various applications. To make this vision a reality, our team focused much of its efforts on the design of a bioreactor, a self-contained apparatus that would be able to carry out all the processes needed for our fuel's production. Our bioreactor concept is based on a modular, compact, efficient and safe device, which allows individuals and communities to produce a supply of their own biodiesel using garden wastes, such as grass clippings, as the inputs for production.
The design process has allowed our team to proceed from the abstract to the qualitative. Largely an iterative process, as alluded to by Suh et al. (2005), at each step in design new information is generated and it is necessary to evaluate the results in terms of the preceding step. Our team applied these insights and carried out several phases of design that progressively will allow us to engineer a functional apparatus.
Process Flow Mapping
In the first stage of design, the processes that would be required to be carried out within our bioreactor were determined. Through completing a process-flow map, we were able to determine the required order of various processes, their relation to one another, and the required inputs and resultant outputs of each. This stage further allowed our team to visually see the progression of our biodiesel synthesis.
Design Specifications
Next, we used this created map to determine the components that would be required within our bioreactor to successfully carry out these processes. Efficiency considerations were of most importance throughout this next stage of design. Where possible, we incorporated the reuse of reagents. Moreover, considerations of safe and environmental waste disposal were taken into account. The following is a representative diagram of our initial sketches of the required components of our bioreactor proceeded by descriptions of each part.
| Reactor Part | Description |
|---|---|
| Growth/ Reaction Chamber | This is an all in one chamber in which the N. Crassa is grown, and later reacted with Methanol and HCl to produce our biodesiel. |
| Air Inflow | Allows oxygen to be given to N. Crassa during growth |
| Medium Input | Allows the addition of growth substrates (waste biomass) |
| Drainer with Filter | Removes media from the N. Crassa before esterification. The filter does not have to be small because N. Crassa forms a mat that is easily seperated from liquid media |
| Methanolic HCl Input | Adds methanolic HCl for the esterification Reaction |
| Water Input | After the reaction is finished, adds water to help better separate the non-polar methyl ester product (our biodesiel) |
| Hexane Input | Adds Hexane to solubilize the biodiesel |
| Mixing arms | Mixes the water and hexane for more efficient extraction |
| Liquid-liquid separator | Separates the water layer from the hexane layer |
| Vapour-liquid separator | Vaporizes the hexane (which is recycled) and leaves the raw biodesiel (which can be incorporated as a mixture in conventional desiels, or used on it's own depending on chain length of the methyl ester) |
| Neutralizer/Condenser | Neutralizes the acidic water layer, and allows methanol to be distilled (which is then recycled) |
| Waste Sump | Cleans the water by getting rid of extra organic components from N. Crassa using bacteria (much like a sewage treatment plant) |
Product Design
In the final stage of our product development, our team plans to transfer our design specifications into an industry-standard blueprint that can used in the building of our bioreactor. Outside the scope of our specialties, our team has been in correspondence and plans to work with Lisa Brown, a Ph. D. student in the Faculty of Engineering, to assist us with these efforts. Our team has also been in correspondence with several undergraduate engineering clubs at the University of Alberta, which have offered their assistance in the building of a prototype. Should we be given the opportunity to present our project at the iGEM World Finals at MIT, we hope to then unveil a working model of our bioreactor.
To help illustrate what we envision our bioreactor to look like, we enlisted the help of design student, Skye Olsen-Cormack, who kindly was able to provide us with a sketch of how our finished product might appear. Four top inlets are present for chemical (hexane, methanol, methanolic HCl) and biomass input; two side outlets are present for biodiesel and liquid waste collection. A solar panel is also depicted on the top of our apparatus, which will provide the energy required.
Considerations
Safety
The use of some of the chemicals in our production process may potentially create safety issues. Some of these chemicals can be volatile and corrosive, and so care must be taken for their storage and large-scale use.
Organism Release
Release of Neurospora does not pose a significant safety threat. Please refer to our safety page for a full description of Neurospora safety and specific corresponding environmental considerations.
Environmental Impact
Water usage is an important factor in considering the environmental impact of our bioreactor. We would like to recycle as many production components as possible, including water, so that they may be returned back to the environment without any harmful effects. For starters, water has to be neutralized and the methanol distilled off. The methanol can then be recycled back into the process. At this point though, the water will still contain dead matter and thus requires further processing, probably through a waste management system.
Scale Up
A cheaper way to extract the FAMES would be to use gasoline (octane) instead of hexane, resulting in a biodiesel enriched gasoline product. Other ways of extracting the FAMES without using fossil fuel products include using chloroform and removing it using a nitrogen stream. To increase efficiency, a non-polar solvent with a boiling point above the reaction temperature could be added to the reaction, for example toluene. However, the problem of removing this solvent after the reaction is complete would arise.
References
- Kumar AV, Suh NP, Arakere NK, Kim NH: Engineering Design. CRC Press LLC; 2005.
- Magnetrol Industries: http://us.magnetrol.com/industries.aspx?industry=4&button=3
