Team:Kyoto/Human Practices/Gold2
Summary
Our first idea was to collect microplastics included in washing wastewater with a biological filter. In order to optimize our plan of using a filtering system, we interviewed a Japanese textile company "T" and gained a lot of knowledge about synthetic fibers. We learned that synthetic fibers are very small and light that might go through the filter. Then, we decided to visit a wastewater treatment plant to see how wastewater is actually treated. Here we found that almost all wastewater treatment plants collect wastes by settling then not filtering. This is because it will cost a lot of money and need frequent maintenance. After visiting, we decided to change the method to precipitate microplastics with biological tools similar to what is done in the treatment plant. To realize this plan from the perspective of synthetic biology, we visited Japanese chemical industry "S" which produces flocculants used in cleaning water. We learned that a flocculant is a polymer and has numerous binding sites that bind to substances that don’t carry electric charge. Looking for such a biological polymer protein to use as a device, we found an ideal flocculant-like protein,” Encapsulin” . Without integrated human practice work, we might haven’t reached to this protein.
First Idea
Interview -Japanese Textile Company “T” -
We thought we need to know more about synthetic fibers before we began the experiment. Thus, we interviewed a Japanese textile company “T” and was able to know the properties of synthetic fibers. According to the staff, microfibers are so small and light that microfibers probably go through a wastewater treatment plant and not be collected. The staff recommended us to go to the treatment plant to know more about the feature of the filtering system. They also gave us samples of synthetic fibers which we used in our experiments(link/experiment-result). The fibers were the best materials to see how effective our devices were.
Visiting -A Wastewater Treatment Plant-
Next, we visited a local wastewater treatment plant to know how they treat wastewater. The staff said that most of the wastewater treatment plants have been collecting wastes by settling them and then degraded by various kinds of bacteria. It was a surprising fact for us because we thought the filtration system would be the major method. They said that the filtration system costs a lot and takes time to maintain for sustainable use. They said it would be difficult to establish the filtration system since the amount of wastewater is too big and it takes a long time to process that many. Furthermore, we learned that the concentration of microfibers in wastewater is very low. This human practice had a good impact not only on the idea of the device but also modeling part because they taught us concrete velocity of sewage and how long it takes to process wastewater. (link/modeling)
Second Idea
Since we found there were several challenges from previous human practice work, we needed to come up with a better way than the filtration system. As mentioned in the previous part, wastewater treatment plants collect wastes with bacterial degradation by settling them and we had an inspiration from that. However, microfibers in wastewater are too low for them to get precipitated so in order to settle microfibers down, we have to aggregate them in a bigger size. General wastes are usually aggregated by using flocculants. so applying this system to biological devices that can aggregate microfibers, that we could collect them as precipitations in wastewater treatment plants.
Visiting - Japanese Chemical Industry “S” -
Although we decided to collect microfibers by settling them as precipitations, we had no idea what we were going to use. Then, a staff of the wastewater treatment plant introduced us Japanese chemical industry "S" which produces flocculants. According to the staff, flocculants are polymers and therefore have numerous binding sites, and few flocculants can bind to substances which don’t have an electric charge. We thought if we find some protein which has a flocculant-like property, we would be able to precipitate microfibers by protein-like flocculants.
Third Idea
To realize our plan, we found an ideal protein which has a property like that of flocculants, Encapsulin. Encapsulin is a protein-made capsule-like nanostructure and we can attach any protein to both of its outside and inside of its surface. It can aggregate microfibers efficiently because it can have much more plastic-binding proteins to its surface than other monomer or dimer proteins . In addition to the flocculant-like property, it is not a genetically engineered organism, but just a protein, which makes it biologically safe to use at home. To sum up, encapsulin, which has plastic-binding protein is the most suitable tools to settle microfibers as precipitation. In order to apply it to our device and put it into practice, we should consider the price of the device and the place it should be attached to. As for the price, we took questions about the cost of our device to the visitors of Kyoto University Academic day 2019 to decide a proper price.(link/HP silver) Next, regarding the place, the human practice to the wastewater treatment plant help us come up with an appropriate way. In order to aggregate fibers efficiently, we have to apply the protein to washing water where the concentration of fibers is higher. According to the staff of the plant, the concentration of microfibers in wastewater treatment plants is very low. Thus, we thought the best way is to apply the protein dissolution to a drain pipe of a washing machine and settling the protein-microfiber complex as precipitation. Finally, we decided to attach our device to the drainpipe of washing machines.(link/hardware)
