Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with an annual of almost 70 million tons manufactured worldwide. It is widely used in packaging, construction, electrical and other industries, such as beverage bottles, films, and engineering plastics . As the public is actively recycling plastic materials, the effect is also limited, abundant of plastic waste is still burned, landfill, recycling into the ecosystem, which not only affects the ecological environment, but also endangers human body. Moreover, there are also quite a few issues in the existing production process of recycled PET products.
Since many PET products are for one-time use and are inexpensive, the amount of waste is large. At the same time, it has good mechanical properties, is difficult to degrade in the nature, as consumes a large amount of industrial processing, and it is easy to cause environmental pollution during the processing process, so the recycling cost is high, resulting in the recycling volume of PET has been maintained at about 30%, the recycling volume is small, and a large number of PET products cannot be recycled when exposed to the environment and unable to be degraded naturally for a long time. Therefore, it is the best way to find an environmentally friendly and efficient degradation method to reduce recycling costs.
In recent years, bio-recycling has been favored because it can provide a "green way" for the recycling of PET. So far, many PET degrading enzymes have been discovered, and these enzymes can indeed depolymerize amorphous or low crystallinity PET to a certain extent. However, they lack the ability to crack the high crystallinity PET commonly used in the production of beverage bottles.
Our project this year improves the thermal stability of PET to increase its catalytic efficiency for PET. If this bio-enzyme we modified can be used in industry in large quantities, it will solve the problem of high cost, difficult degradation and low utilization of PET products, environmental pollution and a series of problems.
End users we proposed
End users: companies and some environmental organizations that recycle and reuse PET products.
For this purpose, we visited a PET bottle production company, Tianjin Industrial Zijiang Packaging Co., Ltd. We learned a series of data and information about plastic bottle production from the company, and learned that they produce 170 million Coca-Cola bottles every year. They believed that the current plastic pollution is very serious since they manufactured a large amount of PET products every year while the recycling is so limited. Therefore, we introduced the biodegradation method to the staff of the company, they thought that it is a good way to solve the plastic pollution. And they also hope to promote it vigorously if it can be effective.
We also consulted Tianjin COFCO Coca-Cola Co., Ltd., a company that uses abundant PET products every year. We learned that Coca-Cola has raised the slogan of "World Without Waste", it also committed to promoting the closed-loop economy of PET packaging products, and has cooperated with some foreign companies to develop the recyclable plastic (RPET). However, the traditional physical and chemical method, currently used recycling and degradation method, still has problems like high cost and mechanical loss. So the number of the RPET products they obtained are limited and the price is too high, which makes it difficult to promote on a large scale.
At the same time, we also introduced the biodegradation method to the staff, elaborated the specificity of PETase for high crystallinity PET and our commitment on improving its thermal stability will promote the industrial application of the PETase, and show that the enzymatic hydrolysis method will further promote the realization of the PET closed-loop economy, which has aroused great interest to the staff. They expressed their interest in our project and are willing to provide corresponding hcPET materials for our experiment in the coming year. Learn more about in the HP-Enterprise visits
Finally we consulted a company specializing in PET recycling, Yingchuang Recycling. It is understood that their current method of recycling PET is still the traditional way. After listening to the introduction of our project, they showed their willing to develop in-depth with us if our result is finally verified to be feasible. In the meantime, they pointed out that the biodegradation method is not only of great significance to their company, but also to the entire PET recycling industry. They are looking forward to our results to greatly save their expenses and increase their efficiency of recycling.
When consulting relevant organizations majoring in the environmental protection, we study that the pollution of microplastic in the marine has developed into a desperate and urgent problem. Through the communication, we came up with a new idea that we can use the PETase we modified in the degradation facilities. They agreed with our idea and thought it of huge market application value, and they are also willing to cooperate closely with us in our subsequent experiments.
The way others use this project in our vision
We will upload our achievements on relevant websites, and contact some PET recycling enterprises with the intention of cooperation to provide our solutions. After our advanced PETase is made, we will donate or sell the finished product to them.
The implement of our project in the real world
Due to the impact of COVID-19, we were unable to access the school laboratory. We plan to produce several good results of our advanced PETase that we have screened and modified, use hcPET to measure their catalytic activity and select the one with the best performance for batch production. Then, we will give it to the above three companies we have contacted before, and make further modifications according to their feedback. Finally, we will carry out mass production of the transformed PETase, and truly put it into the market, so as to make a practical contribution to the cause of world environmental protection.
In the subsequent experiment, we will test whether the modified enzyme is harmful to the environment, whether it will aggravate the environmental pollution and do harm to other energy sources, whether it will cause some damage to the human body and cause some other diseases, or if it raises other security issues that are not been considered at present. We will put it into use after the biological safety of the enzyme is verified.
Other challenges we consider
We sent a questionnaire to the public around the world before and in the middle of the project. Although the final results are very optimistic, there are still a small number of people do not agree with the use of biodegradation, refuse to use gene and protein editing technology, and some think the biodegradation method is unnecessary. Therefore, the promotion of our biodegradation and the use of biodegradable enzymes may be hindered to a certain extent. Many people have raised concerns about the biosafety of the modified enzymes, so it is necessary for us to prove the biosafety of our advanced PETase.
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