Team:SCUT-China A/Integrated Practices/applied design
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Sulfur Killer
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South China University of tecnology
GuangZhou,China
Overview
In order to get a comprehensive assessment of our project on the application of biodesulfurization, we have accomplished our human practices mainly on the following five aspects of work.
First of all, we made a statistical analysis of all the iGEM projects related to environmental issues in recent years and expressed our expectations. Overall, we hope to explore the full potential of biodesulfurization and spare no efforts to promote it. Also, based on our knowledge of the current situation of oil desulfurization combined with relevant data analysis, we put forward an idea of designing a project with BIODESULFURIZATION as its theme. When we generally finished designing the project framework, we used online survey to get a better understanding of how people are aware of and concerned about the BIODESULFURIZATION, and we will try to come up with corresponding solutions to dispel their concerns.
Secondly, we communicated with professor Liu Zehua on several questions raised in our questionnaire. Professor Liu gave us lots of good advice, and pointed out some new problems that we need to solve.
Thirdly, we compared the cost estimation of using E.coli for desulfurization, which was calculated based on collected data, to that of other oil desulfurization methods, and it turned out that our project has significant advantages on economic benefits. Consequently because of the prominent economic efficiency, biodesulfurization using engineered E.coli would be a good choice for enterprises as well as for oil production.
Fourthly, we confirmed the feasibility of our project on industrial production, and designed a specific industrial desulfurizing procedure.
Last, we have made a proposed policy about bio-safety. Then we succeed arranging a meeting with the Guangzhou Environmental Protection Administration, from whom we want to obtain good suggestions for reference to finalize our program and ensure the bio-safety of our product application.
Pre-investigations and Formulation of our project
First of all, we made a data pool, which is the statistics of all environmental projects in iGEM from 2008 to 2015, to stress the increasing importance of environmental protection.
There are some representative data.
Table 1 The data of all environmental projects in iGEM from 2008 to 2015
Figure 1 The number of environmental projects each year
Figure 1 indicates the tendency of the increasing number of all iGEM projects and environmental projects over time. While in 2013, the number of all iGEM projects obviously decreased, and in 2014, the number of environmental projects obviously decreased. The highest proportion is in 2013.
It means that the attention iGEM teams draw on environment is stabilized. They try to protect environment using synthetic biology, but there aren’t many feasible ideas for this part.
Table 2 The number of environmental projects in six continents from 2008 to 2015
Figure 2 The number of environmental projects in six continents from 2008 to 2015
Table 2 & Figure 2 count the number of environmental projects from six continents during these 8 years. We can find that the number is similar among Europe, Asia and North America.
Table 3 The number of different types of environmental projects
Figure 3 The number of different types of environmental projects
Figure 3 lists out all the number of different kinds of environmental projects respectively. As the data shows evidently, the water pollution draws the largest attention. And most projects are focused on the treatment of heavy metal in water.
Through this data pool, we got a whole picture of iGEMteams’ awareness of environmental protection all over the world. And contrast to teams in Europe, Asia and North America, we can draw a conclusion that other continents’ people perhaps pay less attention to environmental protection. The reason maybe that countries in these continents still focus on developing economics and industry. We hope that more international aid would be served to those countries to help them, which would also have profound meaning to our only home—the earth.
Previously we learned that sulfur pollution has great negative effect on environment. However, we found that few of the previous iGEM projects were really related to oil desulfurization, even in those projects about air pollution treatments. Therefore, our project with the theme of oil desulfurization, aimed at protecting the environment, becomes a brand new idea among all the environmental protection-related iGEM projects.
Questionnaire
1.What do you think are the causes of acid rain and haze?
2.What do you think are the most urgent environmental problems to be solved?
Acid rain and haze have adverse impact on people's life and health, to which the exhaust emission of petroleum refinery is considered to be the main cause.
3.Do you think it is necessary to raise the current standard of sulfur emission?
the standard of sulfate emission is thought to be raised.
4.What do you concern about BDS?
We will continue further study after we succeed in constructing the bacteria.
We plan to improve our project by designing a system that is able to collect and kill those bacteria after their enzymes are inactive in oil-processing plant.
And in the option of "other", some people raise a concern that during the fermentation the E.coli will produce an odor even if they don’t in the process of biodesulfurization, which will affect the people living near the fermentation factories. And we will try to find some ways to solve this problem.
Communication
Communication with Professor Liu from SCUT Department of Environment and Energy
After hearing our project, he expressed his worries about the potential threats of our project to the environment, and suggested that a suicidal mechanism should be built for our engineered bacteria, for which an efflux pump is recommended.
Also, professor Liu pointed out that the economic benefits of our project may not be so great even if our project is able to improve the quality of oil. Because commonly the tail gas produced by oil burning will pass a filter device that blocks the sulfur gases from entering the atmosphere. Therefore, in his opinion, we should make a comprehensive assessment of our project comparing to the current sulfur filter device, in order to pursue the optimal economic efficiency.
As for the environment, the higher efficiency of oil desulfurization means better quality petroleum, which means less pollution.
Professor Liu also provided many valuable suggestions on the preciseness of the experiment part, including making blank control to ensure that the degradation of DBT to HBP is the work of our engineered bacteria rather than other inorganic factors. Besides, he gave us some guidance on how to evaluate the cost of our project.
From the communication, we were provided with expert advice and suggested that we should pay more attention to both safety and economic benefit to ensure the feasibility of the industrial productive application of our product.
Assessment of Economic Benefit
On the problem concerning economic benefit, we compared the cost among traditional hydrodesulfurization, biodesulfurization by B4 strain, and biodesulfurization by engineered E.coli, which is our project.
In traditional hydrodesulfurization, the cost of the devices of hydrodesulfurization which need to sustain more than 300 centigrade degree temperature and 2000 kpa pressure is averagely 50 million yuan, in some cases even up to 300 million yuan. Regardless of other expense, HDS still costs a lot more than biodusulfurization.
As for biodesulfurization using Rhodococcus erythropolis IGTS8 strain which is cultivated only in lab, the price of the culture medium is 66.7 yuan per liter, while the culture medium for E.coli strain cultivation in industry costs averagely 0.0308 yuan per liter. It is obvious that using E.coli strain for biodesulfurization is much more cheaper than using Rhodococcus erythropolis IGTS8 strain.
In summary, our product has remarkable advantage on the aspect of economic efficiency.
For the problem of the calorific value of oil, during the experiment we find that E.coli can remove the toxic HBP to a certain extent with its own efflux system.
Industrial Application Aesign
Application Design
To combine our product with the practical oil production, we think it is appropriate to put the biodusulfurizing procedure upstream of oil deusulfurization.
In the BDS pathway, we first add IPTG-induced engineered bacteria, which is our product, into the mixure of oil and water, and the bacteria would stay in the oil and water interface. Keep stirring for about three hours. During the mixing the HBP will enter the oil phase, while bacteria come back into the water phase. Then by using centrifugation the oil and water are layered. The upper layer is oil, and the water and bacteria are retained in the lower layer. Finally the oil will be dehydrated and then enter the fractionating device for distillation. Finally the oil will be dehydrated and then enter the fractionating device for distillation, and the bacteria in the water will be treated in postprocessing.
For the biological safety, our application design of setting the BDS before hydrodesulfurization (Please turn to apply design to learn more about it.) could help reduce the risk of biological pollution. Even if there will be germs survived and remaining in the oil phase,they will be killed during the process of hydrodesulfurization. If a suicidal system is thought to be safer, we will also consider importing one into our engineered bacteria..
Safety of BDS Industrial Application and The Policy
We did some researches on laws of environment in China, learning the standard of oil sulfur and the regulations of refining petroleum. Then, based on the data measured in the lab, we put forward some policies about the standard of oil sulfur, regulations of industrial applications, and ensurance of biological safety.
For the concerns about biological safety, not only will we import suicidal mechanism into our engineered bacteria, but also we’ve put forward specific regulations and policies shown as below:
A.Detect the content of thiophene compound in refined oil products.
B.Monitor the cycle and processing of waste water produced by desulfurization.
C.Detect the amount of waste water germs.
D.Refineries that discharge untreated waste water without permission will be ordered to suspend operations for rectification.
We want to discuss our proposed policy with officers of Guangzhou environmental protection administration to obtain some expert advice that could help with our project. We’ve been contacting them, and we are waiting for their response, hoping to arrange a formal meeting and discuss about our project.
The standard is possible to be changed after industrial test.
We think the policies we proposed can also be used by others as a good example.
Supplements For Policy & System Of Oil Development
We hope that through our project, we could raise people’s awareness of some current policy and system defects. Therefore, to promote the coordinated development of eco-environmental protection and enterprise, we appeal to the government and relevant departments to take the following measures mainly on three aspects.
①The government should improve the legal system of environmental protection for oil development，and implement permit system in the market of oil development，cut down the consumption of oil resources as much as possible, introduce certain economic instruments such as enforcing environmental performance bonds payment and practicing compulsory insurance system in environmental duty, to regulate the development of oil companies.
②Enhance public awareness of environmental protection by strengthening environmental education. People safeguard their own rights and interests of the environment and express their wishes to government and enterprises in view of the environmental information disclosure, taking part in environmental protection organizations and using legal means.
③During production process, oil companies should take into account the requirements of the public, develop programs of environmental-friendly production in accordance with the Government's environmental laws and regulations. Promote cleaner production and pollution control technique in the production process, in order to improve oil energy efficiency.
Communication with FAFU Team
After the CCIC, a special strain of E.coli that has the odour gene knocked out was sent to us by FAFU team, to help with our bacterium stinking problem, which is considered to be a big obstacle to the industrial applications of our engineered bacteria. We succeed to solve the odor problem.
The Proposed Policy about Bio-safety We Make
