Team:Calgary/HP/Silver
Human Practices Silver
safety
Visit our safety page to learn in detail how we adapted our project to fulfill various safety considerations. First, we looked into best practices of engineering system controls and considered applied design safety on Mars by identifying likely points of failure. Next, we considered the various biohazard concerns on the International Space Station and Mars, focusing on both physical and genetic forms of biocontainment. To ensure our own safety, team received full biosafety lab training before commencing any wet lab work and followed all safety protocols.
Engagement
Click the link to learn about how we gave back to our community by hosting workshops and developing teaching and learning tools regarding synthetic biology, iGEM in general, and specific aspects of our project.
Collaborations
Click the link to read an issue of our Canadian iGEM Newsletter organized by our team member Helen Wang, as well as our wet lab collaboration with McMasterU where we tested their DNAzyme and GLOWzyme.
Choosing an application
We wanted our system of PHB production and secretion to be applied in the real world, but were unsure where it could be best implemented. W knew our project had real demand in many areas concerning human waste management, upcycling, and creating biodegradable plastics, and narrowed down the scope of our search to four applications which seemed to have theoretical support:
- sewage from wastewater treatment plants
- sewage in developing countries
- fermented liquid runoff known as landfill leachate, and
- solid human waste collected during missions in outer space.
After consultations with industry, discussions with advisors and experts, and a tour of the Pine Creek Wastewater Treatment Plant in Calgary, we decided to evaluate the demand, cost, impact, and available resources of each of these applications could have. Most importantly, we used the findings for each application to carefully consider whether or not synthetic biology was the best approach. Ultimately, we decided that applying our design to long-term interplanetary space missions of the future would be the most valuable use of our system. Our findings and reasoning are summarized below.
Table 1: Comparing different applications of our engineered E. coli . Click on each coloured link to learn more:
Wastewater Treatment
Small-Scale Wastewater Treatment in Developing Countries
Landfill Leachate Treatment
Outer Space
Demand
Moderate
High
Low
High
Costs
High
Moderate
Moderate
Low
Impact (safety, environment, society, economy)
Low
High
Low
Moderate
Available resources and industry contacts
Many
Some
Few
Many
Is synthetic biology best?
Not yet
Not yet
Not yet
Yes
Figure 1: Our team after a tour of the Pine Creek Wastewater Treatment facility in Calgary!
WASTEWATER TREATMENT
Demand
According to Polyferm, a Canadian polymer company, bioplastics are not in high demand due to high cost of production. If they were produced at a cost and efficiency similar to petroleum-based plastics, demand would increase. To rephrase, there will be a demand for bioplastics once an efficient large-scale process is developed. This application would thus only make sense if our E. coli produce PHB with high efficiency.
Cost
The cost of implementing pure cultures into current wastewater treatment systems is extremely high, as this process would require new, separate systems. Currently, the Pine Creek Wastewater Treatment Plant in Calgary processes about 1 million cubic meters of waste per day. The chemical oxygen demand (COD) and PHB yield were assumed to be 1000 mg/L and 0.11 kg of PHB per kg of COD, respectively, for our calculations. We estimated that 28,100,000 kg of PHB would be produced per year for wastewater treatment facilities in Calgary. With a price of $5 per kg of PHB (Choi & Lee, 1997), we estimated revenues of $140-141 million.
Impact
There is limited impact felt by the average consumer, and municipal taxes may actually increase to account for the costs in implement this system. However, if successful, this system could help PHB become a desirable alternative to traditional petroleum-based plastics. PHB is also a higher-value product than the biogas already produced in wastewater treatment plants.
Is synthetic biology the best solution?
Not yet. The low viability of pure cultures of PHB-producing bacteria in wastewater has been deemed too costly. Current research indicates mixed cultures best balance efficiency and cost. Our engineered E. coli could not survive in a mixed culture, as they would likely be outcompeted for resources.
DEVELOPING COUNTRIES
Demand
In developing countries, our team envisioned PHB production incorporated into smaller-scale wastewater treatment systems in communities that lacked established treatment methods. There is a large demand for wastewater treatment of any kind in developing countries. Current waste management strategies in some areas of the developing world are a hazard to human health. Thus, implementing our system in developing countries would improve sanitation, as the waste can be remediated after our E. coli use it. In addition, biodegradable plastic would help with the problem of plastic waste disposal in these countries (as bioplastics would degrade without need for landfill space, while current petroleum-based plastics are a major pollutant worldwide).
Cost
To gauge cost, we compared PHB production between genetically engineered bacteria and natural bacterial communities in sludge, which have been previously used to feasibly produce PHB. Assuming a community size of 2000 people, solid waste generation of 3.113 x 10-3 m3/day/person (Palanivel & Sulaiman, 2014), COD content of 601 mg/L, COD to PHB conversion of 0.11 for mixed cultures and 0.88 for pure cultures (Rhu et al., 2003) and a price of $5 per kg of PHB (Choi & Lee, 1997), we found that using pure cultures results in additional $2,000 in revenues. However, the cost of sterilization of the waste stream before inoculation with pure culture was estimated at $100,000 (Choi & Lee, 1997).
Is synthetic biology the best solution?
Not yet. PHB secretion may make the process more user-friendly, but the costs of sterilization and maintaining a pure culture will be too high. Thus, a small-scale PHB production and wastewater treatment plant will not be able to profit from the current process.
LANDFILL LEACHATE TREATMENT
Demand
According to PolyFerm, bioplastics are not in very high demand due to high cost of production. If they were produced at a cost and efficiency similar to petroleum-based plastics, demand would increase. Treatment of landfill leachate is also a very niche field; we have only identified one project dealing with this issue (the Calgary Leachate Pilot Project). The integration of PHB production in leachate treatment would likely be unfeasible due to low volumes of leachate that are usually produced at landfills (see "Cost" section for a detailed breakdown of the calculations which led us to make this statement). Since the environmental problem and the manufacturing problem are both not urgent in this application, the overall demand for our E. coli in leachate treatment is very low.
Cost
In Calgary, a single landfill generates about 100,000 L of leachate per day. Although COD content in leachate is higher than in wastewater, the estimated amount of PHB produced in Calgary was about 8000 kg/year, based on COD content of 1977 mg/L in Calgary leachate (Kashef & Lungue, 2016). In addition, a new system will need to be implemented to collect VFAs in fermenters and process them in bioreactors. The estimated cost of such a system is $140-215 million. If done on-site at the Calgary Pilot Leachate Treatment Plant, there would be reduced transportation costs, as leachate would not need to be transferred from landfills to treatment plants. Our system must compete economically with deep-well injections. Potential revenues for estimated amounts of PHB that can be produced per year in various locations are as follows:
- Calgary: $40,000
- Hong Kong: $4.5-15 million
- Vancouver: $16 million
Based on our calculations, it would be more feasible to implement our system in cities like Hong Kong and Vancouver.
Impact
By using landfill leachate, we could reduce leachate holding times, which could reduce the chance of leachate leaking into groundwater and prevent toxins (e.g. ammonia) from forming. Less toxins reduces overall leachate treatment costs while mitigating negative impacts it may have on nearby groundwater and the surrounding environment.
Figure 2: A screenshot of the Skype call we had with Col. Christ Hadfield to discuss the possibilities of applying our project in space!
OUTER SPACE
Demand
Waste management is an issue in space, as future interplanetary travellers will be producing waste over long periods of time. Storage of the waste is not the best solution, and ejecting it into space cannot occur when astronauts are on the surface of another planet like Mars. Burying human waste raises the ethical issue of possibly polluting a foreign environment; therefore, remediation of the waste is the best option. With regards to the material produced after the remediation, bioplastics can be used in space the same way that traditional petroleum-based plastics can. One benefit to utilizing bioplastics such as PHB in space is that powdered PHB can be used to 3D-print materials needed by astronauts. In addition, byproducts like water can be remediated to product potable sources, and solid waste can be converted to char via torrefaction for use as radiation shielding, building materials, or food substrates.
Cost
There is a high cost associated with developing an entire waste-to-product system from scratch. However, creating a larger bioplastic production system for human colonies on Mars would ultimately decrease the cost of raw material that needs to be shipped into space. According to NASA, the cost of shipping supplies to space using SpaceX Dragon spacecraft is $27,000 per pound. The costs saved by producing 41 kg of PHB in space would then be about $2,440,000. Our team contacted a 3D printing company called 4G Vision Tech that uses selective laser sintering (SLS), which can be used to 3D print with PHB (Pereira et al., 2012). Howard from 4G Vision Tech approximated that the predicted amount of PHB can be used to create approximately 50 hydroponic systems and 20 general tools like wrenches, hammers, and scissors. Currently, Made In Space Inc. has tested out the use of 3D printers on the International Space Station, and SLS 3D printing would be feasible on the surface of Mars.
Impact
This project could help a future Mars colony achieve greater independence. In addition, managing solid human waste is a pressing need that NASA is currently trying to address. So far, most methods of waste disposal have been deemed unfeasible. There is a less direct impact to most people on Earth in the present time. However, our system can prove to be an important development in NASA's endeavours towards Mars colonization.
WORKS CITED
Choi, J., & Lee, S. (1997). Process analysis and economic evaluation for Poly(3-hydroxybutyrate) production by fermentation. Bioprocess Engineering, 17(6), 335-342
Coats, E., VandeVoort, K., Darby, J., & Loge, f. (2011). Toward Polyhydroxyalkanoate Production Concurrent with Municipal Wastewater Treatment in a Sequencing Batch Reactor System. Journal Of Environmental Engineering, 137(1)
Kashef, O., & Lungue, L. (2016). Successes of The City of Calgary’s Leachate Treatment Pilot Plant, and Use of Treated Leachate to Build a Greener Future. Presentation.
Leachate treatment in China: Technologies and Import Opportunities", 2015
Palanivel, T., & Sulaiman, H. (2014). Generation and Composition of Municipal Solid Waste (MSW) in Muscat, Sultanate of Oman. APCBEE Procedia
Pereira, T., Oliveira, M., Maia, I., Silva, J., Costa, M., & Thiré, R. (2012). 3D Printing of Poly(3-hydroxybutyrate) Porous Structures Using Selective Laser Sintering. Macromolecular Symposia, 319(1), 64-73. http://dx.doi.org/10.1002/masy.201100237
Rhu, D., Lee, W., Kim, J., & Choi, E. (2003). Polyhydroxyalkanoate (PHA) production from waste. Water Science & Technology, 48(8), 221-228
Rose, C., Parker, A., Jefferson, B., & Cartmell, E. (2015). The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology. Critical Reviews In Environmental Science And Technology, 45(17), 1827-1879. http://dx.doi.org/10.1080/10643389.2014.1000761
Vancouver landfill 2016 annual report. (2017)
Zhang, Ylikorpi, T., & Pepe, G. (2015). Biomass-based Fuel Cells for Manned Space Exploration Final Report
safety
Visit our safety page to learn in detail how we adapted our project to fulfill various safety considerations. First, we looked into best practices of engineering system controls and considered applied design safety on Mars by identifying likely points of failure. Next, we considered the various biohazard concerns on the International Space Station and Mars, focusing on both physical and genetic forms of biocontainment. To ensure our own safety, team received full biosafety lab training before commencing any wet lab work and followed all safety protocols.
Engagement
Click the link to learn about how we gave back to our community by hosting workshops and developing teaching and learning tools regarding synthetic biology, iGEM in general, and specific aspects of our project.
Collaborations
Click the link to read an issue of our Canadian iGEM Newsletter organized by our team member Helen Wang, as well as our wet lab collaboration with McMasterU where we tested their DNAzyme and GLOWzyme.
Choosing an application
We wanted our system of PHB production and secretion to be applied in the real world, but were unsure where it could be best implemented. W knew our project had real demand in many areas concerning human waste management, upcycling, and creating biodegradable plastics, and narrowed down the scope of our search to four applications which seemed to have theoretical support:
- sewage from wastewater treatment plants
- sewage in developing countries
- fermented liquid runoff known as landfill leachate, and
- solid human waste collected during missions in outer space.
After consultations with industry, discussions with advisors and experts, and a tour of the Pine Creek Wastewater Treatment Plant in Calgary, we decided to evaluate the demand, cost, impact, and available resources of each of these applications could have. Most importantly, we used the findings for each application to carefully consider whether or not synthetic biology was the best approach. Ultimately, we decided that applying our design to long-term interplanetary space missions of the future would be the most valuable use of our system. Our findings and reasoning are summarized below.
Table 1: Comparing different applications of our engineered E. coli . Click on each coloured link to learn more:
Wastewater Treatment
Small-Scale Wastewater Treatment in Developing Countries
Landfill Leachate Treatment
Outer Space
Demand
Moderate
High
Low
High
Costs
High
Moderate
Moderate
Low
Impact (safety, environment, society, economy)
Low
High
Low
Moderate
Available resources and industry contacts
Many
Some
Few
Many
Is synthetic biology best?
Not yet
Not yet
Not yet
Yes
Figure 1: Our team after a tour of the Pine Creek Wastewater Treatment facility in Calgary!
WASTEWATER TREATMENT
Demand
According to Polyferm, a Canadian polymer company, bioplastics are not in high demand due to high cost of production. If they were produced at a cost and efficiency similar to petroleum-based plastics, demand would increase. To rephrase, there will be a demand for bioplastics once an efficient large-scale process is developed. This application would thus only make sense if our E. coli produce PHB with high efficiency.
Cost
The cost of implementing pure cultures into current wastewater treatment systems is extremely high, as this process would require new, separate systems. Currently, the Pine Creek Wastewater Treatment Plant in Calgary processes about 1 million cubic meters of waste per day. The chemical oxygen demand (COD) and PHB yield were assumed to be 1000 mg/L and 0.11 kg of PHB per kg of COD, respectively, for our calculations. We estimated that 28,100,000 kg of PHB would be produced per year for wastewater treatment facilities in Calgary. With a price of $5 per kg of PHB (Choi & Lee, 1997), we estimated revenues of $140-141 million.
Impact
There is limited impact felt by the average consumer, and municipal taxes may actually increase to account for the costs in implement this system. However, if successful, this system could help PHB become a desirable alternative to traditional petroleum-based plastics. PHB is also a higher-value product than the biogas already produced in wastewater treatment plants.
Is synthetic biology the best solution?
Not yet. The low viability of pure cultures of PHB-producing bacteria in wastewater has been deemed too costly. Current research indicates mixed cultures best balance efficiency and cost. Our engineered E. coli could not survive in a mixed culture, as they would likely be outcompeted for resources.
DEVELOPING COUNTRIES
Demand
In developing countries, our team envisioned PHB production incorporated into smaller-scale wastewater treatment systems in communities that lacked established treatment methods. There is a large demand for wastewater treatment of any kind in developing countries. Current waste management strategies in some areas of the developing world are a hazard to human health. Thus, implementing our system in developing countries would improve sanitation, as the waste can be remediated after our E. coli use it. In addition, biodegradable plastic would help with the problem of plastic waste disposal in these countries (as bioplastics would degrade without need for landfill space, while current petroleum-based plastics are a major pollutant worldwide).
Cost
To gauge cost, we compared PHB production between genetically engineered bacteria and natural bacterial communities in sludge, which have been previously used to feasibly produce PHB. Assuming a community size of 2000 people, solid waste generation of 3.113 x 10-3 m3/day/person (Palanivel & Sulaiman, 2014), COD content of 601 mg/L, COD to PHB conversion of 0.11 for mixed cultures and 0.88 for pure cultures (Rhu et al., 2003) and a price of $5 per kg of PHB (Choi & Lee, 1997), we found that using pure cultures results in additional $2,000 in revenues. However, the cost of sterilization of the waste stream before inoculation with pure culture was estimated at $100,000 (Choi & Lee, 1997).
Is synthetic biology the best solution?
Not yet. PHB secretion may make the process more user-friendly, but the costs of sterilization and maintaining a pure culture will be too high. Thus, a small-scale PHB production and wastewater treatment plant will not be able to profit from the current process.
LANDFILL LEACHATE TREATMENT
Demand
According to PolyFerm, bioplastics are not in very high demand due to high cost of production. If they were produced at a cost and efficiency similar to petroleum-based plastics, demand would increase. Treatment of landfill leachate is also a very niche field; we have only identified one project dealing with this issue (the Calgary Leachate Pilot Project). The integration of PHB production in leachate treatment would likely be unfeasible due to low volumes of leachate that are usually produced at landfills (see "Cost" section for a detailed breakdown of the calculations which led us to make this statement). Since the environmental problem and the manufacturing problem are both not urgent in this application, the overall demand for our E. coli in leachate treatment is very low.
Cost
In Calgary, a single landfill generates about 100,000 L of leachate per day. Although COD content in leachate is higher than in wastewater, the estimated amount of PHB produced in Calgary was about 8000 kg/year, based on COD content of 1977 mg/L in Calgary leachate (Kashef & Lungue, 2016). In addition, a new system will need to be implemented to collect VFAs in fermenters and process them in bioreactors. The estimated cost of such a system is $140-215 million. If done on-site at the Calgary Pilot Leachate Treatment Plant, there would be reduced transportation costs, as leachate would not need to be transferred from landfills to treatment plants. Our system must compete economically with deep-well injections. Potential revenues for estimated amounts of PHB that can be produced per year in various locations are as follows:
- Calgary: $40,000
- Hong Kong: $4.5-15 million
- Vancouver: $16 million
Based on our calculations, it would be more feasible to implement our system in cities like Hong Kong and Vancouver.
Impact
By using landfill leachate, we could reduce leachate holding times, which could reduce the chance of leachate leaking into groundwater and prevent toxins (e.g. ammonia) from forming. Less toxins reduces overall leachate treatment costs while mitigating negative impacts it may have on nearby groundwater and the surrounding environment.
Figure 2: A screenshot of the Skype call we had with Col. Christ Hadfield to discuss the possibilities of applying our project in space!
OUTER SPACE
Demand
Waste management is an issue in space, as future interplanetary travellers will be producing waste over long periods of time. Storage of the waste is not the best solution, and ejecting it into space cannot occur when astronauts are on the surface of another planet like Mars. Burying human waste raises the ethical issue of possibly polluting a foreign environment; therefore, remediation of the waste is the best option. With regards to the material produced after the remediation, bioplastics can be used in space the same way that traditional petroleum-based plastics can. One benefit to utilizing bioplastics such as PHB in space is that powdered PHB can be used to 3D-print materials needed by astronauts. In addition, byproducts like water can be remediated to product potable sources, and solid waste can be converted to char via torrefaction for use as radiation shielding, building materials, or food substrates.
Cost
There is a high cost associated with developing an entire waste-to-product system from scratch. However, creating a larger bioplastic production system for human colonies on Mars would ultimately decrease the cost of raw material that needs to be shipped into space. According to NASA, the cost of shipping supplies to space using SpaceX Dragon spacecraft is $27,000 per pound. The costs saved by producing 41 kg of PHB in space would then be about $2,440,000. Our team contacted a 3D printing company called 4G Vision Tech that uses selective laser sintering (SLS), which can be used to 3D print with PHB (Pereira et al., 2012). Howard from 4G Vision Tech approximated that the predicted amount of PHB can be used to create approximately 50 hydroponic systems and 20 general tools like wrenches, hammers, and scissors. Currently, Made In Space Inc. has tested out the use of 3D printers on the International Space Station, and SLS 3D printing would be feasible on the surface of Mars.
Impact
This project could help a future Mars colony achieve greater independence. In addition, managing solid human waste is a pressing need that NASA is currently trying to address. So far, most methods of waste disposal have been deemed unfeasible. There is a less direct impact to most people on Earth in the present time. However, our system can prove to be an important development in NASA's endeavours towards Mars colonization.
WORKS CITED
Choi, J., & Lee, S. (1997). Process analysis and economic evaluation for Poly(3-hydroxybutyrate) production by fermentation. Bioprocess Engineering, 17(6), 335-342
Coats, E., VandeVoort, K., Darby, J., & Loge, f. (2011). Toward Polyhydroxyalkanoate Production Concurrent with Municipal Wastewater Treatment in a Sequencing Batch Reactor System. Journal Of Environmental Engineering, 137(1)
Kashef, O., & Lungue, L. (2016). Successes of The City of Calgary’s Leachate Treatment Pilot Plant, and Use of Treated Leachate to Build a Greener Future. Presentation.
Leachate treatment in China: Technologies and Import Opportunities", 2015
Palanivel, T., & Sulaiman, H. (2014). Generation and Composition of Municipal Solid Waste (MSW) in Muscat, Sultanate of Oman. APCBEE Procedia
Pereira, T., Oliveira, M., Maia, I., Silva, J., Costa, M., & Thiré, R. (2012). 3D Printing of Poly(3-hydroxybutyrate) Porous Structures Using Selective Laser Sintering. Macromolecular Symposia, 319(1), 64-73. http://dx.doi.org/10.1002/masy.201100237
Rhu, D., Lee, W., Kim, J., & Choi, E. (2003). Polyhydroxyalkanoate (PHA) production from waste. Water Science & Technology, 48(8), 221-228
Rose, C., Parker, A., Jefferson, B., & Cartmell, E. (2015). The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology. Critical Reviews In Environmental Science And Technology, 45(17), 1827-1879. http://dx.doi.org/10.1080/10643389.2014.1000761
Vancouver landfill 2016 annual report. (2017)
Zhang, Ylikorpi, T., & Pepe, G. (2015). Biomass-based Fuel Cells for Manned Space Exploration Final Report
Engagement
Click the link to learn about how we gave back to our community by hosting workshops and developing teaching and learning tools regarding synthetic biology, iGEM in general, and specific aspects of our project.
Collaborations
Click the link to read an issue of our Canadian iGEM Newsletter organized by our team member Helen Wang, as well as our wet lab collaboration with McMasterU where we tested their DNAzyme and GLOWzyme.
Choosing an application
Collaborations
Click the link to read an issue of our Canadian iGEM Newsletter organized by our team member Helen Wang, as well as our wet lab collaboration with McMasterU where we tested their DNAzyme and GLOWzyme.
We wanted our system of PHB production and secretion to be applied in the real world, but were unsure where it could be best implemented. W knew our project had real demand in many areas concerning human waste management, upcycling, and creating biodegradable plastics, and narrowed down the scope of our search to four applications which seemed to have theoretical support:
- sewage from wastewater treatment plants
- sewage in developing countries
- fermented liquid runoff known as landfill leachate, and
- solid human waste collected during missions in outer space.
After consultations with industry, discussions with advisors and experts, and a tour of the Pine Creek Wastewater Treatment Plant in Calgary, we decided to evaluate the demand, cost, impact, and available resources of each of these applications could have. Most importantly, we used the findings for each application to carefully consider whether or not synthetic biology was the best approach. Ultimately, we decided that applying our design to long-term interplanetary space missions of the future would be the most valuable use of our system. Our findings and reasoning are summarized below.
| Wastewater Treatment | Small-Scale Wastewater Treatment in Developing Countries | Landfill Leachate Treatment | Outer Space | |
|---|---|---|---|---|
| Demand | Moderate | High | Low | High |
| Costs | High | Moderate | Moderate | Low |
| Impact (safety, environment, society, economy) | Low | High | Low | Moderate |
| Available resources and industry contacts | Many | Some | Few | Many |
| Is synthetic biology best? | Not yet | Not yet | Not yet | Yes |
WASTEWATER TREATMENT
Demand
According to Polyferm, a Canadian polymer company, bioplastics are not in high demand due to high cost of production. If they were produced at a cost and efficiency similar to petroleum-based plastics, demand would increase. To rephrase, there will be a demand for bioplastics once an efficient large-scale process is developed. This application would thus only make sense if our E. coli produce PHB with high efficiency.
Cost
The cost of implementing pure cultures into current wastewater treatment systems is extremely high, as this process would require new, separate systems. Currently, the Pine Creek Wastewater Treatment Plant in Calgary processes about 1 million cubic meters of waste per day. The chemical oxygen demand (COD) and PHB yield were assumed to be 1000 mg/L and 0.11 kg of PHB per kg of COD, respectively, for our calculations. We estimated that 28,100,000 kg of PHB would be produced per year for wastewater treatment facilities in Calgary. With a price of $5 per kg of PHB (Choi & Lee, 1997), we estimated revenues of $140-141 million.
Impact
There is limited impact felt by the average consumer, and municipal taxes may actually increase to account for the costs in implement this system. However, if successful, this system could help PHB become a desirable alternative to traditional petroleum-based plastics. PHB is also a higher-value product than the biogas already produced in wastewater treatment plants.
Is synthetic biology the best solution?
Not yet. The low viability of pure cultures of PHB-producing bacteria in wastewater has been deemed too costly. Current research indicates mixed cultures best balance efficiency and cost. Our engineered E. coli could not survive in a mixed culture, as they would likely be outcompeted for resources.
DEVELOPING COUNTRIES
Demand
In developing countries, our team envisioned PHB production incorporated into smaller-scale wastewater treatment systems in communities that lacked established treatment methods. There is a large demand for wastewater treatment of any kind in developing countries. Current waste management strategies in some areas of the developing world are a hazard to human health. Thus, implementing our system in developing countries would improve sanitation, as the waste can be remediated after our E. coli use it. In addition, biodegradable plastic would help with the problem of plastic waste disposal in these countries (as bioplastics would degrade without need for landfill space, while current petroleum-based plastics are a major pollutant worldwide).
Cost
To gauge cost, we compared PHB production between genetically engineered bacteria and natural bacterial communities in sludge, which have been previously used to feasibly produce PHB. Assuming a community size of 2000 people, solid waste generation of 3.113 x 10-3 m3/day/person (Palanivel & Sulaiman, 2014), COD content of 601 mg/L, COD to PHB conversion of 0.11 for mixed cultures and 0.88 for pure cultures (Rhu et al., 2003) and a price of $5 per kg of PHB (Choi & Lee, 1997), we found that using pure cultures results in additional $2,000 in revenues. However, the cost of sterilization of the waste stream before inoculation with pure culture was estimated at $100,000 (Choi & Lee, 1997).
Is synthetic biology the best solution?
Not yet. PHB secretion may make the process more user-friendly, but the costs of sterilization and maintaining a pure culture will be too high. Thus, a small-scale PHB production and wastewater treatment plant will not be able to profit from the current process.
LANDFILL LEACHATE TREATMENT
Demand
According to PolyFerm, bioplastics are not in very high demand due to high cost of production. If they were produced at a cost and efficiency similar to petroleum-based plastics, demand would increase. Treatment of landfill leachate is also a very niche field; we have only identified one project dealing with this issue (the Calgary Leachate Pilot Project). The integration of PHB production in leachate treatment would likely be unfeasible due to low volumes of leachate that are usually produced at landfills (see "Cost" section for a detailed breakdown of the calculations which led us to make this statement). Since the environmental problem and the manufacturing problem are both not urgent in this application, the overall demand for our E. coli in leachate treatment is very low.
Cost
In Calgary, a single landfill generates about 100,000 L of leachate per day. Although COD content in leachate is higher than in wastewater, the estimated amount of PHB produced in Calgary was about 8000 kg/year, based on COD content of 1977 mg/L in Calgary leachate (Kashef & Lungue, 2016). In addition, a new system will need to be implemented to collect VFAs in fermenters and process them in bioreactors. The estimated cost of such a system is $140-215 million. If done on-site at the Calgary Pilot Leachate Treatment Plant, there would be reduced transportation costs, as leachate would not need to be transferred from landfills to treatment plants. Our system must compete economically with deep-well injections. Potential revenues for estimated amounts of PHB that can be produced per year in various locations are as follows:
- Calgary: $40,000
- Hong Kong: $4.5-15 million
- Vancouver: $16 million
Based on our calculations, it would be more feasible to implement our system in cities like Hong Kong and Vancouver.
Impact
By using landfill leachate, we could reduce leachate holding times, which could reduce the chance of leachate leaking into groundwater and prevent toxins (e.g. ammonia) from forming. Less toxins reduces overall leachate treatment costs while mitigating negative impacts it may have on nearby groundwater and the surrounding environment.
OUTER SPACE
Demand
Waste management is an issue in space, as future interplanetary travellers will be producing waste over long periods of time. Storage of the waste is not the best solution, and ejecting it into space cannot occur when astronauts are on the surface of another planet like Mars. Burying human waste raises the ethical issue of possibly polluting a foreign environment; therefore, remediation of the waste is the best option. With regards to the material produced after the remediation, bioplastics can be used in space the same way that traditional petroleum-based plastics can. One benefit to utilizing bioplastics such as PHB in space is that powdered PHB can be used to 3D-print materials needed by astronauts. In addition, byproducts like water can be remediated to product potable sources, and solid waste can be converted to char via torrefaction for use as radiation shielding, building materials, or food substrates.
Cost
There is a high cost associated with developing an entire waste-to-product system from scratch. However, creating a larger bioplastic production system for human colonies on Mars would ultimately decrease the cost of raw material that needs to be shipped into space. According to NASA, the cost of shipping supplies to space using SpaceX Dragon spacecraft is $27,000 per pound. The costs saved by producing 41 kg of PHB in space would then be about $2,440,000. Our team contacted a 3D printing company called 4G Vision Tech that uses selective laser sintering (SLS), which can be used to 3D print with PHB (Pereira et al., 2012). Howard from 4G Vision Tech approximated that the predicted amount of PHB can be used to create approximately 50 hydroponic systems and 20 general tools like wrenches, hammers, and scissors. Currently, Made In Space Inc. has tested out the use of 3D printers on the International Space Station, and SLS 3D printing would be feasible on the surface of Mars.
Impact
This project could help a future Mars colony achieve greater independence. In addition, managing solid human waste is a pressing need that NASA is currently trying to address. So far, most methods of waste disposal have been deemed unfeasible. There is a less direct impact to most people on Earth in the present time. However, our system can prove to be an important development in NASA's endeavours towards Mars colonization.
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