Team:Calgary/Human Practices
Human Practices
The team focused on evaluating the feasibility of four proposed project applications: integrating PHB production with landfill leachate treatment, integrating PHB production in a wastewater treatment plant, integrating PHB production in developing countries, and the production of PHB on Mars from human waste.
Landfills
Landfill leachate treatment is an avenue that we considered when looking at possible applications of our project on Earth. Leachate is the fermented runoff liquid that accumulates underground at landfills, and as a feedstock, it is rich in organic matter. It is highly toxic and becomes dangerous to the environment when left untreated as it can leak into nearby groundwater, causing contamination.
Conventional technologies used in leachate treatment do not include the production of value-added products, and current technologies appear to be concerned with the simple removal of toxic, undesired components. Leachate transfer methods include recycling and combining it with the treatment of domestic sewage, biodegradation for waste decomposition, and chemical and physical methods involving oxidation, adsorption, chemical precipitation, coagulation/flocculation, sedimentation/flotation and air stripping. Integrating a PHB-producing stage into conventional leachate treatment would facilitate the production of PHB out of the waste, cutting down the cost of treatment and allowing the facilities to become profitable. One problem associated with this feedstock is can be contaminated with heavy metals, which decreases the rate of growth and PHB production in our bacteria. This would mean that the leachate would have to be treated to remove heavy metals prior to fermentation with our bacteria, and is a costly process.
Wastewater Treatment Plants
Our project also had the potential to provide a method by which wastewater treatment facilities could take the biological material in wastewater and transform it into a value-added product. Part of our Integrated Human Practices included a visit to our local wastewater treatment facility. Pine Creek is a new wastewater treatment facility in Calgary, which treats sludge to produce methane and uses the treated sludge as a fertilizer.
This tour served the purpose to gather information regarding this application. Sludge produced during conventional municipal wastewater treatment is a nutrient-rich material that looks promising for the PHB production industry. Currently, sludge is treated to remove organic matter and toxins. Removal of organic matter is achieved by fermentation, where the organic matter is broken down into volatile fatty acids (VFAs) and is afterward digested by bacteria to produce methane and carbon dioxide. We researched on the use of sludge as a feedstock for PHB production and showed the process to be feasible, but not yet economical. One of the major downsides of industrial-scale PHB production is the use of toxic chemicals - chloroform in the extraction and purification of PHB bioplastic. We also found that along with the extraction and purification expenses, the profitability of this option was not ideal.
Developing Countries
After learning that wastewater treatment was not profitable, we turned our focus to developing countries. Since the first two applications we considered were of greater concern in the developing world than in areas where effective wastewater treatment and plastic recycling already exist, we decided to look into implementing our system as a small-scale wastewater treatment option for communities in the developing world. Selling PHB would provide a monetary incentive to construct a wastewater treatment system, which, in turn, will reduce the incidence of water-borne disease. Challenges arise concerning the cost of our product and the lack of a user-friendly platform.
Space
While the previously-mentioned wastewater feedstock is a promising source of VFAs, the cost of implementation in current treatment facilities is high. In addition, the control of naturally-existing bacteria in the wastewater is inadequate, meaning a pure culture of our engineered E. coli would be outcompeted.
The implementation of our PHB production process in space is a novel solution in the treatment of the solid human waste. Currently, human waste is left untreated and is transported back to Earth where it burns upon re-entering the Earth's atmosphere. NASA has been investigating different ways of utilizing human waste during space expeditions and on Mars, yet the use of human stool in the production of PHB was not yet discussed. This encouraged us to look at the project idea as a novel idea worthy of investigation. Furthermore, the high level of sterility of the process supports the growth of pure bacterial culture. Even more, the PHB produced in space can then be used in Selective Laser Sintering (SLS) 3D printing necessary tools on demand.
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