Hardware

In our first proposal, we followed the idea of protecting the environment by minimizing the natural resources we utilize while maximizing the scope of application. Thus, our first design does not require electricity and minimizes the cost of human and physical capital.

Our inspiration came from the buoy structure of leaf collectors that float on water without any physical support. We try to mimic that buoyancy of the leaf collector by making the bioreactor hollow in the middle with two openings on the sides, allowing water to flow into the reactor at a controlled rate. We included a filter with each opening less than one microliter to prevent cyanobacteria from leaking into the ocean. Aside from that, we also considered the possibility of Cyanobacteria floating upwards out of the reactor. Therefore, we increased the size of the opening at the bottom to ensure that the water inflow at the top is less than the water outflow at the bottom, achieving biosafety.

After confirming our design, we made a model to prepare for 3D printing. Focusing on our low-cost goal, the components required for the building are minimal, only including material with high buoyancy to build the shell and a 1-micrometer filter in the middle.

After finishing the modeling, we contacted our school to create 3D printing of our product to gain a direct idea of what improvements needed to be made.

Through discussion and tests with the basic inflow and outflow of the reactor, we realized that this design is unsuitable to reproduce and lacks stability in its function. The first problem with this design is that, to ensure the functioning and align with our core target, we need to be highly selective for this version’s material: The material needs to buoyant, doesn't rust easily, and is not made by PET. This means that the starting material for this design is limited, making it unsuited for reproduction and wider spread. Another problem with this is that when testing the buoyancy, we realized that the reactor is susceptible to severe weather or other changes in the environment.

This version lacked stability, and it does not guarantee biosafety. Therefore, we decided to improve the existing version by making it land-based instead of water-based to increase its stability and efficiency.

As microplastic pollution affects marine ecosystems, it also impacts human health. Microplastic inhalation can cause oxidative damage, DNA damage and mutation, which are known risks for cancer development [1]. Therefore, we thought of building a life-based design that cuts off its harm from the source by preventing the microplastic particles from entering the body.

We wanted to make our products convenient for the public to use in their daily lives, so we chose to design a bioreactor that could be attached to plastic bottles, a common source of microplastic intake in people’s daily lives. Screwing a cap off a plastic bottle brings about 500 microplastic particles. In average we consume about 16000 microplastic particles in a single year from bottled water [2] This data reflects how targeting plastic bottles is an effective way of reducing the harm of microplastic pollution on people’s health.

The filter includes a valve above the plastic bottle that ensures the colonies of Cyanobacteria and Rhodococcus can be isolated from the water before being used. There will be a space above the valve for Cyanobacteria and Rhodococcus to survive. Above the cultivation area, there is an extra filter to ensure that bacteria will not be exposed to the environment. When used, the valve will open, and the Cyanobacteria and Rhodococcus can filter and degrade microplastics in water. As our consumers drink or pour out water, the filter layer will trap the Cyanobacteria and Rhodococcus to prevent it from going out, violating biosafety guidelines.

We bought a shower filter to build the live base. We chopped off the “head” of the shower filter used to connect to a pipe. Then adding a plastic bottle cap to the shower filter. It took a lot of time to polish the shower filter after we chopped off the “head” because, without a smooth surface, it would be hard to glue the plastic bottle cap on the filter. We cultivated Cyanobacteria and Rhodococcus in the cavity of the filter. Lastly, we added nano-filtration, which can ensure that Cyanobacteria and Rhodococcus will not be exposed to our environment.

The low cost to create one reactor reflects its effective minimization of input, especially as the starting materials are bought at market price to create one single product. It would cost even less if it was produced wholesale. This contributes to realizing the goal of wide production with low cost.

Because of the long growth period of cyanobacteria, we decided to test only the ability of the reactor to filter microplastic particles. To test the function of this reactor, we mixed microplastic particles which could be identified by our eyes. After the solution went through the filter, the microplastic particles are filtered out of, proving the testing to be successful. Aside from the scientific testing, we also received feedback from our team members on this design. They told us, when they knew that Cyanobacteria and Rhodococcus would directly contact with the water they drink, they would feel disgusted by it. This feedback helped us to reflect on areas that needed improvement.

The low level of acceptance reflected the need for a wider spread of how our reactor works. We concluded that it is necessary to help our potential customers and understand that behind this design is a scientific and safe theory for both the human body and environment.

Our goal for the bioreactor is still degrading down microplastic. Therefore, we continued to improve on the 1st version that emphasizes solving environmental microplastic contamination. Considering the potential need of energy, we decide to utilize the energy from nature — tides.

The average height of tide can reach roughly 91cm (about 2.99 ft), which can provide natural energy that can allow the water to flow from high to low. This enables the water to go through all the Cyanobacteria and Rhodococcus that produce protein to degrade microplastic while being ecofriendly. The ocean water would flow from the top of the reactor and will be stored in the reactor. As ocean water reaches a certain amount, the protein produced by and Rhodococcus will come out of the pores of the Cyanobacteria incubator and be released into the water tank. The protein will then degrade microplastic in the water tank and after a certain time, it will be released and go back into the ocean.

We made a 3D model for the ocean wave bioreactor.Materials we need

• Acrylic plate/organic glass as the outer shell
• Tubes that contain holes with nano filter to ensure that only enzymes and water come out, not the cyanobacteria
• Water pump to gain fresh water
• Air pump to ensure the input of air for cyanobacteria

The most important testing involves the feasibility of utilizing tide wave as a source of water input, therefore, we used a bottle of water to test this. With the strong force of the tide pushing, the gate was able to open and collect amounts of water. We also tested the pipeline system, where enzymes could go through the minute pores and protein can be released.

Our previous design, working on mechanism, over-relied on the strength of tides, making it unstable and inefficient when regarding water inflow. Moreover, we consider the inclusion of Rhodococcus in our system to further break down TPA into CO₂, also providing a source of input to Cyanobacteria. Therefore, a separation will need to take place while allowing Rhodococcus to have direct contact with the TPA.

Through research and investigations, we have decided to also make further improvements to the pervasiveness of the product. More specifically, we decided to create a product that could fit in both salt and freshwater environments. To achieve this, we must consider how to edit our system to keep cyanobacteria functioning under salt water. Therefore, we have two sub-versions.

For this version, we focused on creating a self-sustained system applied in wetlands with fresh water with the use of cyanobacteria and rhodococcus sequentially.

The bioreactor is designed to be set above the wetland. Water with microplastics gets pumped from the environment into the bioreactor through the water pump. Being pulled down by gravity, water flows through the first layer of filter with cyanobacteria, which breaks PET down into EG and TPA. Water with TPA then flows down through the second layer of filter with rhodococcus, breaking TPA and EG down into CO₂ and H₂O. The filtered water is then released back into the environment with CO₂ and H₂O acting as the reactants of photosynthesis, creating a self-sustained system of degrading.

For building, we decided to proceed with the modeling to gain a concise view when building the bioreactor.

Material Includes:

• Organic glass to be the main components of bioreactor's shell and central structure.
• 1 micrometer filters
• Water pump to transport freshwater from the environment could be wetlands, rivers etc.

The design for our saltwater bioreactor is based on freshwater design. Our cyanobacteria (Synechococcus elongatus PCC 7942) are freshwater cyanobacteria which cannot survive in saltwater conditions. We decided to utilize this property to apply a self-suicide system.

We utilized a timing motor system and two water pumps to create this self-suicide system. Our first water pump is connected to the box containing cyanobacteria and Rhodococcus seeds. Our timing system will keep the water gate closed for 2 weeks to cultivate cyanobacteria and enable enzyme release. Once the 2-week period is over, our timing system will open the water gate between the cultivation area and the degrading area, releasing the cyanobacteria and the enzyme produced by the cyanobacteria, at the same time, the water gate of the water pump connecting the outer environment and the reactor will also open, allowing the seawater containing microplastic particles to flush inside killing the cyanobacteria while the enzyme. This process is also given a 2-week period, and the cycle goes on.

The structure is based on the freshwater version with the attachment of one more water pump, a storage tank holding freshwater and cyanobacteria seeds, and a timer that motivates the water gates connected to the water pumps.

The completed final version is the combination of our lessons learned from our past versions. We will be implementing this into further testing and production. If this version of design is proven to function with efficiency and stability, we are prepared and confident to introduce this product to the market and increase our influence on society with our knowledge and strength.