Inspiration

In our motherland, Taiwan, the color in the sky often turns gray from blue. The PM2.5 which has attracted increasing attention is not just a local issue but also a global problem. Those who are sensitive to air pollution usually feel uncomfortable and wear a face mask all the time. However, indoor air quality was proved to 10 times worse than outdoors and often ignored by people. Modern people stay much more time inside the house or a closed area. Thus, it’s emergent to solve these problems. Moreover, we want to do human practices to raise the awareness of indoor air quality.

Indoor Air Quality

Poor air quality significantly affects our daily lives. Gases, chemicals, and other pollutants in the air can cause us headaches, eye irritations, allergies, fatigue, etc. The direct way to improve indoor air quality is to simply open the window, but sometimes the air outdoors is even worse than the air indoors, and therefore we cannot open the window in these kinds of situations due to a plentiful amount of pollutants such as toxic gases and PM (particulate matter) particles outdoors.

Air Purifiers

The air purifiers can help a little by filtering some of these particles, but there are still issues with CO2 and toxic gases such as volatile organic compounds (VOCs), which air purifiers cannot remove all kinds of them through filtering.

CO2 and VOCs investigation and their effects

CO2 and some kinds of VOCs, which can hardly be dealt with through air purifiers, can cause problems to our health. High concentration of CO2 indoors links to a direct adverse effect on human performance, while a small amount of VOCs can easily cause a negative impact on us.

We measured the CO2 concentrations of the common places indoors and learned a lot about the relationship of how people feel about indoor air quality through human practices research,

• 450~700 ppm: the air is fresh, and it doesn’t cause any effects to people
• 700~1000 ppm: people feel stiffness and have more complaints
• 1000~2500 ppm: people sense that the air is turbid and start feeling drowsy
• 2500~5000 ppm: people get headache, lethargy, sluggishness, heartbeat hasten, and mild nausea
• above 5000 ppm: it may cause severe hypoxia or coma

More CO2 concentration analysis of our work in commonplaces of our daily lives (e.g., the classroom, auditorium, table-tennis room, school bus, gym and the vehicle) was presented in Human Practices page.
For VOCs as benzene and chloroform, a little of them will make people eye, nose and throat irritation, while inhaled excess of them will damage to liver, kidney and central nervous system. A brief exposure to 3000 ppm of benzene will make people headache, 10000~20000 ppm will result in confusion and heart rate going rapid and long exposure may cause death. Accordingly, the indoor concentrations of benzene ranged upto 3.4 times the outdoor concentrations, which is a crucial problem in our lives because people spend more and more time indoors.
The problem of excessive CO​2 and VOCs​ indoors is indeed widely existing in our daily life and may have severely influenced our health. So we must come up with a solution to solve these problems.

Our Goal

We have gone to National Chung Hsing University, Taichung, Taiwan to search for current methods and come up with a better way.

Physics-Physical absorption:

• Using organic or inorganic solvents(For example: Propylene Carbonate,, and ocean water.) as absorbents
• Using solid absorbents, such as carbon or Zeollte to absorb carbon dioxide
• Disadvantages:
  1. The absorption is deteriorated due to the sulfide, causing the number of regeneration to lessen.
  2. The absorption isn't effective

Chemistry-​Chemical absorption:

• The chemical reaction between the absorbent and carbon dioxide is used to recycle CO​2​,and the reverse reaction is used to regenerate the absorbent.
• Disadvantage: There are many operational variables, making it more cumbersome to operate.

Biology-Biological absorption:

Our approach:

Since the solubility of CO​2​ is low in water, we combine biology and chemistry method, inserting the gene that can produce carbonic anhydrase(CA, which can increase the solubility of CO​2​ in water) into ​bacillus subtilis. T​hen use light and high photosynthesis efficiency algae to purify the water quality.

Comparison:

Physics and chemical methods must be done in lab, while our approach can be used in any place. The physics method needs very large space in the application place especially, comparing to our device, it’s light and portable.

Experiment design

We use Bacillus to secrete enzymes out of the bacteria to achieve continuous production of CA enzyme without destroying the cell wall. As for algae, we choose cyanobacteria to match the appropriate temperature and illuminance to achieve better result.

Procedure:

1. Insert the gene that can produce carbonic anhydrase(CA) into ​bacillus subtilis​
2. Use light and high photosynthesis efficiency algae to purify the water quality.

pBS0EP​liaI ​ promoter / pBS0E
BGSCID: ​ECE742
PliaI is an inducible promoter from B. subtilis, and it was first developed in The Bacillus BioBrick Box 2.0​.We have got this part from BGSC(​http://www.bgsc.org/​).

shine dalgarno / pSB1C3
Sequence:AAAGGAGGAA
It’s within the primer we designed to replicate the CA (Synpcc1792_1388 & Sypcc1447) sequence.

CA (​Synpcc7942_1388​ & ​Synpcc7942_1447​)
We have got the algae which has the CA sequence from National Chiao Tung University, Taiwan. With PCR(Polymerase chain reaction), the CA part is able to connect with the primer. To compare the different rate of dissolving carbon dioxide, we used Synpcc7942_1388 & Synpcc7942_1447 sequence respectively.

Terminator / pSB1C3
part: ​BBa_B0015
This is the most commonly used terminator in gene cloning with the consisting of Double terminator BBa_B0010 and BBa_B0012. We also get this part from iGEM Jamboree in its Spring 2019 Distribution-2019 Kit Plate 3.

• reduce the concentration of CO​2​ in enclosed space efficiently
• portable
• moderately sized
• intelligence control is available (IoT)
• algae in the device can be used again

In order to solve the high concentration of carbon dioxide in enclosed space, we invented our product to deal with the problem simply (without special equipments). The followings are the methods and the advantages of our device.

Application

Since our device is portable, it can be used everywhere.The followings are the places that often contains high CO​2 ​concentration and can be easily improve by using our device.

• public transportation
• classroom
• gym
• office
• cafeteria
• house

• Differ from physics or chemistry way, our product can work without special experimental equipments
• Portable and can be used everywhere
• The device operates in a circulation way and is easy to clean up
• The algae we produce can be used in different aspects(ex.fertilizer)
• Improve indoor air quality in an environmentally friendly way

Chen, P.H., Liu, H.L., Chen, Y.J., Cheng, H., Lin, W.L., Yeh, C.H., Chang, C.H., 2012. Enhancing CO2 bio-mitigation by genetic engineering of cyanobacteria. Energy and Environmental Science 5, 8318–8327.