Team:British Columbia/Human Practices/Industry


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British Columbia -

The Applications and Applicability of Engineered Microbial Consortia

Our project sets a foundational advance by engineering microbial consortia with the purpose of distributing metabolic pathways to increase their efficiency, whereby they become more desirable from a biotech standpoint. We thus set out to find the following information from our industrial partners:
  1. What are some potential industrial applications of engineered microbial consortia?
  2. What advantages are there to employing biological methods versus current chemical methods?
  3. How feasible is it to implement biological methods?
  4. Are Research & Development sectors of current organizations/companies interested in pursuing synthetic biology options?

Our Approach

Our team contacted Chevron and arranged a visit to the Chevron refinery in Burnaby, BC, Canada. We communicated with Chevron representatives to find out more about the existing methods of desulfurization and costs of refining crude oil.

We connected with Alberta Innovates – Technology Futures (AITF) representative Karen Budwill and Oil Sands Leadership Initiative (OSLI) representatives John Vidmar and Nicolas Choquette-Levy to discuss the progress of our project and obtain some industrial insights.

Industrial Insights

From our Chevron visit, we learned:
  1. How refinery desulfurization works:
    • Sulfur-rich fuels are catalytically hydrogenated (hydrotreated) at high pressure (700 psi) and temperature (800 °F), creating H2S gas.
    • The H2S gas is absorbed from the fuel stream by being contacted with amines at high pressure.
    • The amines are then heated to release the H2S gas to the two-step Claus process.
    • In the first step of the Claus process, the H2S gas is partially combusted, creating water, elemental sulfur and sulfur oxides.
    • The Claus process's second step catalytically reacts the combustion products with more H2S, creating water and elemental sulfur with very high yields.
  2. Industrial-scale desulfurization is massive. The diesel hydrotreater at Chevron Burnaby treats 18000 barrels of diesel fuel every day, removing 99.5% of the sulfur and taking it from around 500 ppm to less than 15 ppm sulfur at a cost of about $2 per barrel.
  3. Sulfur content in fuel is regulated by governments because sulfur-containing fuels lead to acid rain. As time has gone on, the permitted sulfur content has decreased. The kinetics of conventional hydrotreatment cause the cost of treating 100 ppm sulfur fuel down to 15 ppm to require more extreme process conditions and thus be substantially more expensive than treating 500 ppm sulfur fuel to 100 ppm.
From our correspondence with AITF-OSLI, we learned:
  1. In Alberta, upgrading and refining processes aim to reduce viscosity and desulfurize crude oil to facilitate transport by pipeline.
  2. Presently, the industry does not possess infrastructure for the utilization of biological systems such as bioreactors or emulsifiers. However, this is an area of interest for them and could be implemented in a time span of approximately 5 years. There is also an interest in screening tailings ponds for new organisms or genes encoding parts capable of refining crude oil.
  3. Our AITF and OSLI collaborators are currently looking into the economic and environmental costs of refining oil, as well as our project's potential impact on industry and applications other than desulfurization. They will get in touch with us within a few weeks once they have this information.

Biocatalytic desulfurization of dibenzothiophene: Hypothetical Bioreactor Design

After talking with our industrial collaborators we had a good idea about what the industry was looking for in terms of bio-desulfurization. The next step was to devise a hypothetical design for a small scale bio-desulfurization plant. The general schematic of this plant can be found below (Diagram 1):

Diagram 1. General layout and flow of a bio-desulfurization unit.