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Human Practice


The Exploration-Adjustment-Development-Fixation model, coined by our team, serves as a chronicle documenting the entirety of our team's research and development process, commonly referred to as a "project chronicle." This model adeptly illustrates how our team meticulously navigates the path towards our objectives, emphasizing the imperative of thorough groundwork in addressing societal issues and needs. The essence lies in enabling the team to engage in extensive preliminary work, ensuring that societal issues and demands supersede abstract technological concepts. Each phase of investment necessitates inspiration and feedback from society, fostering a close alignment between the project and the real world, ultimately benefiting humanity.


In this phase, our team invests significant effort into problem identification, problem analysis, and problem confirmation. The objective is to authentically resolve tangible societal issues, steering clear of impractical or ornate problems. While exploring unfamiliar domains, we integrate theory and practice. Grounded in extensive literature review, we actively engage with the community, gaining insights into the real-world context of the research subject and a more concrete understanding of the problem itself.


Beyond exploring the issue, selecting the right approach for problem resolution is paramount. Our team actively interacts with society, avoiding wasteful allocation of resources on an impractical "unsolvable" problem-solving path. Instead, we identify genuine breakthrough points by aligning our capabilities with real-world circumstances, ensuring more efficient issue resolution.


A robust project necessitates comprehensive development. Following the identification of problems and solutions, we undergo a process of "confirming societal needs, theoretically validating needs, and testing needs in reality." This process enables us to precisely meet the demands, allowing us to design products that are not only effective but also satisfying to the stakeholders.


In the final stage, the product undergoes continuous refinement based on shareholder feedback. The goal is to seamlessly integrate our product into existing production lines, opening the door for future production. We aspire for our project to serve not merely as an academic or technological showcase but as a significant contribution to the world. Our objective is to empower shareholders standing alongside us, enabling them to perceive the possibilities. This, in turn, facilitates targeted reforms addressing existing issues in the field, ultimately contributing to a better world.

Overview our Integrated Human Practice through Self-designing Model

The research model we use is "Exploration-adjustment-development-fixation". At the beginning of the project, we explored eagerly after confirming the general direction of "filtering microplastics in water". In this stage, we combine theoretical research and field investigation to gradually understand the branches in the field of "filtration", so as to narrow down the problem and finally lock in the improvement of membrane, targeting the water source in large scale.

However, by interviewing with professionals at the societal level, we found out limits of our focus, which made us to adjust the application scenario of the membrane process from the water source to the drinking water, so as to more directly address human microplastic exposure.

After that, we fully developed the new direction by conducting social surveys of people’s drinking habit, literature reviews, and academic discussions with professors, which set the stage to present the first version of our product.

After the first version coming up, we actively fixed the product for two round by conducting the social surveys and interviews with customer groups and industrial production groups respectively, integrated their suggestions, and finally completed the tew rounds of fixation.


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On this page:



The Origin of Our Program

In our literature review, we initially explored the significant rise in microplastics (MPs) based on an article published by The Guardian. This article briefly outlines the situations in which people are known to ingest these minuscule particles through food, water, and even inhalation[1]. Additionally, recognizing the essential role of water in our lives, we focused our attention on freshwater environments, investigating the presence of MPs in rivers, surface water, reservoirs, and groundwater[2]. Notably, research in China has already been conducted to uncover the occurrence of MPs in freshwater sources[3].

As a result, our team embarked on extensive research to address the issue of microplastics in freshwater. Our efforts led us to identify three potential avenues of action, which are summarized briefly as follows:

  1. Fundamentally reducing plastic production, similar to the efforts of previous teams like Team Exeter and Team Kyoto from https://2019.igem.org, by developing alternative bio-environmental materials.
  2. Genetically engineering existing plastic recycling processes, akin to the approaches taken by previous teams such as Team TU_Kaiserslautern and Team Virginia from https://2019.igem.org , by degrading microplastics.
  3. Directly reducing exposure through improved water filtration systems.

Narrowing Down the Problem

Due to practical limitations (as a high school student team, we carefully considered our time and technology/equipment constraints) and the well-rounded precedents set by other teams, we decided to focus on the third option, briefly summarized as follows: improving existing water filtration systems.

There are many types of water, and domestic wastewater is a critical source of microplastic pollution. The assessment shows that “every person (in the studied area) emits on average 1145 microplastics (25–1000 μm) daily through domestic wastewater, resulting in a yearly discharge of 418,000 microplastic particles per person”. [5]

What is related to domestic wastewater is water treatment plants which play a pivotal role in the operation of cities and companies, so we initiated the roadmap for discovering wastewater filtration to better understand its function.

Consequently, our initial goal was set: starting from large-scale wastewater filtration plants, we aimed to learn their filtration mechanisms and apply this technology to various operations including other types of wastewater that end up in the ocean, air, and human body, and therefore effectively filter out microplastics from water sources.

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Visiting water plant

After setting our goal, we visited the Jingkai Water Plant in Beijing's Yizhuang District, China. Thorough explanations provided by Deputy Plant Manager Zhang, we gained insights into the filtration mechanisms of Secondary Treatment and Tertiary Treatment: MBR (Membrane Bio-Reactor)


Zhang Shaoxuan, current Deputy Plant Manager at Beijing Yizhuang Environmental Technology Group Co., Ltd. He possesses extensive experience in the operation of sewage treatment plants, is well-versed in conventional urban sewage treatment processes like SBR, A2O, and MBR, and has been involved in BOT projects for urban sewage treatment plants. He currently oversees the daily operation and management of the sewage treatment plant.

Zhang Deputy Plant Manager: A/O+MBR membrane is the mainstream sewage treatment process at present, relatively stable, and the process is relatively mature. The MBR membrane operating mode is generally as follows: it runs for 8-12 minutes, pauses for 2 minutes - one cycle, and after running for 6-8 cycles, it undergoes a 3-minute backwash.

Us:In your opinion, do you think there are any urgent issues regarding the use and filtration efficiency of this membrane?

Zhang Deputy Plant Manager: The daily operation of MBR will result in membrane fouling, which includes the accumulation of pollutants such as EPS polysaccharides and proteins, leading to reduced filtration efficiency and higher costs. Therefore, physical flushing is needed about once a week, and chemical cleaning using chemicals such as sodium hypochlorite and oxalic acid is performed.

Discover the Problem

In the filtration system, the role of membranes is always pivotal. Vice Director Zhang provided us with an excellent subject of study, prompting us to delve deeply into MBR research.

Through extensive literature research, we discovered that the utilization of chemical agents in MBR treatment has significant environmental repercussions, such as membrane fouling, accelerated protein and bacteria adsorption, and pollution[6]. Nevertheless, the literature also hints at the potential of biological cleaning methods. Inspired by this, we devised Plan A, with the objective of employing genetic engineering techniques to develop enzymes capable of degrading pollutants. This innovation aims to enable a wider adoption of biological reactor technology in water treatment plants, thereby alleviating membrane fouling issues and enhancing the filtration of water sources. By promoting the broader utilization of such membranes, we can effectively address the problem of microplastics in water across various large-scale water treatment plants.



Shifting the Problem

However, after we presented our well-designed Plan A to the water treatment plant and received feedback from Yin Wenyue, the filtration system engineer, we learned that akin to other traditional methods involving "enzyme degradation of pollutants," Plan A encountered intricate challenges. These challenges encompassed enzyme deactivation, cost implications, degradation rates, secondary pollution concerns, and practical difficulties when implemented on an industrial scale. Despite being theoretically viable and having undergone limited research trials, the industrial application of Plan A continues to pose significant challenges.


Yin Wenyue, a filtering technician responsible for sludge transportation and the use of additives.

Engineer Yin's feedback was sobering. The treatment technology for freshwater is already highly mature, and our team lacks the capability to address its persistent membrane fouling issues. However, we are still determined to tackle the microplastic problem. We realized that the role of filtration systems extends beyond filtering water resources at the source; it can also be applied at the terminal where interaction with humans occurs.

Therefore, our wet lab immediately initiated research into the terminal aspects of the water resource cycle, specifically the ingestion of microplastics by humans. A global survey on drinking water quality revealed that approximately 325 microplastic particles, ranging in size from 6.5 micrometers to 100 micrometers, were found per liter in various brands of bottled water (Mason et al., 2018). These microplastics predominantly leached into the water during the transportation process from the PET plastic bottles and HDPE bottle caps of the bottled water. [For more details, please refer to the wet lab introduction page].

Consequently, we made the decision to shift our overarching objective from "addressing all microplastic exposures in freshwater" to "addressing microplastic exposure from drinking water," with a primary focus on ensuring the provision of clean drinking water. Drawing upon our previous experiences working with the JingKai water treatment plant, we introduced Plan B, which, we opted to design a bottle cap equipped with filtration capabilities. This cap would serve as the final line of defense, preventing human consumption of microplastics. Unlike the filtering system we knew from JingKai water plant, we hope this bottle cap can be environmentally friendly, and also specialize in addressing microplastic ingestion from everyday plastic-packaged drinking water. Moreover, we wish this little cup can be applied to other containers and drinking devices (such as coffee or beverage cups), showing more flexibility than the filtering system in the water treatment plant.

Drawing upon our previous experiences working with the JingKai water treatment plant, we introduced Plan B, which, we opted to design a bottle cap equipped with filtration capabilities. This cap would serve as the final line of defense, preventing human consumption of microplastics. Unlike the filtering system we knew from JingKai water plant, we hope this bottle cap can be environmentally friendly, and also specialize in addressing microplastic ingestion from everyday plastic-packaged drinking water. Moreover, we wish this little cup can be applied to other containers and drinking devices (such as coffee or beverage cups), showing more flexibility than the filtering system in the water treatment plant.



Identify targeted audience’s needs

After we have clarified the problem we want to solve, we need to fully develop it. During this stage of development, we wanted to confirm the needs by investigating the local area and formed a questionnaire to survey residents’ drinking habits.

To comprehensively and objectively reflect the current situation of the problem, the proportion of males and females is close to 1:1 in this study. Regarding that the drinking habits of people inside a single unit of household are consistent, we separated our survey subjects into individual and family. In this way, we could avoid inaccurate data generated by some repeated answers.

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The result shows that bulk water and bottled water together account for the largest proportion of all sources of drinking water. Both people who drink bottled water and people who drink bulk water make up 38.1% of the whole group respectively. Nearly half (40%) of the participants often drink bottled water and 27.5% of them choose to "drink bottled water every day”. In short, drinking water that contains microplastics has occurred frequently in every household.

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Problems came along with it. Most of the barreled drinking water we buy has a large capacity, causing the habit of storing them to form among households. Regardless the time accumulated on the way of delivering bottled water to each household, the data shows that most households store their drinking water(in plastic containers) for a week or longer, and some even reach a month. There is no need to say that, this whole, long process of storage will enable an increasing amount of microplastics to remain in drinking water.


To dive into the topic of microplastics, the data shows that people have already formed a preliminary understanding of microplastics 66.3% of participants have heard of this issue before. Among them, 47.5% of participants believe that plastic bottles have a high likelihood of containing microplastics, 56.5% of them mistakenly believe that microplastics come from food and water sources, and 28.2% of them focus on the bottle itself.

chart-6 chart-7

The result of this survey clearly showed the necessity of our project. Our team believed that this study is reliable and effective enough to reflect that the residues of microplastic in drinking water have begun to receive more and more attention and that under the threat of microplastics, daily drinking water is no longer reassuring.

Theoretical verification

After confirming our project's target audience, we consulted literature to confirm the presence of microplastics in bottled water. Through literature review, we found that in all bottled water, PET packaging had higher concentrations of microplastics compared to other types of packaging, indicating that this packaging is a source of plastic pollution. The literature reported microplastic content in glass bottles and PET bottles, with values of 204 particles per liter (p/L) and 1410 p/L respectively. Plastic items in glass bottles, specifically the plastic layer under the bottle cap, might also release microplastic particles into the bottled water. Literature has proven that a significant portion of microplastic pollution in bottled water comes from mechanical forces experienced by bottles during their whole life cycle, such as squeezing, cleaning, transportation, and storage. Therefore, we conducted preliminary experiments to confirm the presence of microplastics in bottled water.

We sampled and tested bottled water and beverage brands ranking in the top six in market share in both the Chinese and international markets (Aquafina, Nongfu Spring, YiBao, Baishan, Kangshifu Mineral Water, Nestle Pure Life, Kangshifu Ice Tea, and Coca-Cola). We measured the quantity of microplastic particles in each bottled water, confirming the existence of microplastic pollution in the bottled water and beverages we consume in our daily lives.

From our literature review, we learned that bottle caps were considered the main factor responsible for releasing microplastics. Therefore, replacing existing plastic bottle caps is the most effective solution to mitigate microplastic pollution. Additionally, innovative packaging technologies that allow opening the bottle cap in a different way, such as "easy-open caps," could be a potential solution to reduce particle release. Consequently, we discussed solutions for microplastic pollution and ultimately decided to add a simple microplastic filtration device to the bottle mouth (Please refer to the description page for details). The materials used in this device are entirely eco-friendly. The device include two parts: a filter membrane capable of trapping microplastics and a special bottle cap made from cellulose structure. The cellulose structure of the bottle cap can reduce microplastic pollution generated from the production and use of plastic bottle caps. Therefore, the wet team began to design the filtering process used at the bottle mouth. Our design theory, confirmed by Professor A, was proven to be feasible. The specific process can be viewed here:

Testing in real life

After synthesizing the BAM membrane, we needed to conduct BAM membrane effectiveness testing on water samples containing microplastics. The preparation of the microplastics water sample was performed using the following steps:

Materials used:

- PS microplastics 0.1mm microspheres (purchased from [source])

1.1g of plastic microspheres was extracted using an iron spatula. The plastic microspheres were ground for 1 minute using a 6cm ceramic mortar and pestle.

The submerged plastic powder was stirred with 1000ml of ultrapure water using a glass rod for one minute.

Both the pre-test and post-test samples were enriched and sent for inspection using the same procedures as the water sample analysis described earlier. The results of the Raman spectroscopy testing on the pre-filtered samples were similar to the previously presented results, with peak heights resembling the PS spectra in the database. This confirmed that the water samples prepared were essentially free from external microplastic contamination. The results of microplastic content detection showed a 97% reduction in microplastic content.

Design and produce

After confirming that the problem indeed existed in bottled water, our wet lab began to design the filtering process used at the bottle mouth. (Our design theory was proven to be feasible after being confirmed by Professor A. The specific process can be viewed here lab链接】)



Upon the theoretical design completion of our initial bottle cap version, we commenced soliciting feedback from various stakeholders in society. Our shareholders include: filtering engineer, a consumer representative, and a representative from the Bottled Water Company.

  1. The filtering engineer provided a feasibility analysis of our product's design, focusing on its technical aspects.
  2. The consumer representative offered suggestions regarding the user experience.
  3. Bottled Water Company representative elucidated potential challenges that might arise during actual production.

By amalgamating the insights from these three categories of shareholders, we were able to comprehensively refine our product. This iterative process allowed us to explore new possibilities in the realm of mineral water filtration.

First Version

The filtration system technicians from the water treatment plant provided us with valuable insights for our product design. After the first version came out, we chose to revisit Engineer Yin from the JingKai Water Treatment Plant, who had pointed out the limitations of our membrane pollution solution (Plan A). She welcomed our visit and, drawing upon her expertise in filtration systems, offered us several considerations. These factors, combined with her insights, contributed to a more comprehensive and practical design space for our product.


Engineer Yin: Is the membrane renewable?

After hearing this, we made a few improvements to ensure our biofilms are as safe and environmentally friendly as possible. First, we decided to remove harmful cross-linking agents used in making BAM to ensure that the biofilm produced fully complies with bio-environmental standards and can be composted. In addition, we would like to highlight our main raw materials, including bacterial cellulose, bagasse/coffee grounds, attapulgite (APT), lignin, and tea polyphenols. These raw materials are natural materials and fully meet the requirements of biological and environmental protection.


Engineer Yin: How to make sure the water permeability of the composite cellulose membrane?

Based on the common sense of life and the results of real-life experiments, we can draw the following conclusion: The special structure type of bottle cap will cause people to slightly squeeze the bottle body when drinking water, thereby increasing the rate of water passing through the membrane. Therefore, even if there is a slight resistance due to the membrane pore size, it will not lead to a big change in the use experience.


Engineer Yin: Can intercepted microplastics be reused?

Further research is needed. Methods to separate microplastics from membranes are still being explored. At the same time, the recycling of separated microplastic particles needs further exploration.

Second Version



Consumers: When hit by sharp objects, the filter membrane may be damaged.

On this issue, we have further optimized the project.

  1. Stainless steel is added on both sides of the membrane as a support. Set the membrane behind the bottle mouth to absorb shock
  2. The material used to make the bottle cap is elastic. Through continuous testing and improving the mixed ratio, the bottle cap can act as a shock absorber.
  3. Due to time limits, we will improve the manufacturing process of the membrane to make it more durable in the future.

Overall, these improvements make the product more reliable, better able to meet user needs and prolong the service life of the product. Increasing the strength and elasticity of the membrane will make it less likely to break easily.

Production/sustainable development

Consumers: The filter bottle has a single form and may be difficult to adapt to various bottles on the market.

While ensuring the application of biofiltration membrane technology, we conducted detailed research. According to our research, most bottled water caps on the market now adopt a threaded form, which is very common. Therefore, we can solve the problem of bottle size through simple size adjustments. This adjustment can be achieved very easily without any negative impact on the performance of the bottle. Through this improvement, we can ensure the application results of biofiltration membrane technology and make it more suitable for bottled water products on the market.

Third Version

Finally, to ensure the future successful implementation of our project, we wrote emails to major mineral water companies, elaborating on the operational principles of our product. We emphasized its integration within the existing production chains of mineral water and sought societal-level suggestions. (Email records and chat transcripts are available.) Ultimately, we received a response from the Wahaha Mineral Water Company in China. We successfully conducted a video conference with their representatives, including:

  1. Guo Taisong: Master, Zhejiang University; Hangzhou Wahaha Group Co. LTD; Leader of mold and packaging R&D team
  2. Yu Fang: Xi 'an University of Architecture and Technology, Master; Hangzhou Wahaha Group Co. LTD; Product design engineer;
  3. Xu Wen: Jiangnan University, Master; Hangzhou Wahaha Group Co. LTD; Packaging technology engineer;

Their suggestions mainly include the following aspects, and we have made improvements and replies one by one:


The Company: Sterilization measures using ozone, sodium hypochlorite and other disinfectants may damage the structure

Us: Theoretically, since surface treatment is used, sterilization measures will not affect the internal structure. However, we do not rule out the possibility that it may cause damage, and we will test and improve the samples after they are completed.

The Company: In real life, the pressure of squeezing the bottle may cause the pore size of the membrane to increase.

Us: No, because the support structure itself is fixed to a separate steel support structure, squeezing will not deform the membrane and will not change the aperture of the membrane.

The Company: When sealing, the cap leaves an excess when it comes into contact with the mouth of the bottle, and this excess causes the membrane to wear out.

Us: Similarly, because the membrane is fixed in a steel support structure, most of the time it does not rub directly against the cap structure, so the impact of wear is small.

The Company: Cellulose contains hydrophilic groups, will it swell when exposed to water for a long time?

Us: The process we use is from the straw production process, this process will make a surface treatment to the cellulose, separating the hydrophilic groups of cellulose and the outside, thus the support result will not absorb water.


The company: In the production line, the mechanical analysis of in the robotic arm screwing the bottle cap, as well as the strength analysis of cellulose.

Us: For the convenience of the robotic arm and the user, we designed the periphery of the bottle cap with bumps, making it easier for humans and instruments to grip.


Carrington, D. (2021, December 8). Microplastics cause damage to human cells, study shows. The Guardian. https://www.theguardian.com/environment/2021/dec/08/microplastics-damage-human-cells-study-plastic

Mason, S. A., Welch, V. G., & Neratko, J. (2018). Synthetic Polymer Contamination in Bottled Water. Frontiers in Chemistry, 6(407). https://doi.org/10.3389/fchem.2018.00407

Meng, F., Zhang, S., Oh, Y., Zhou, Z., Shin, H.-S., & Chae, S.-R. (2017). Fouling in membrane bioreactors: An updated review. Water Research, 114, 151–180. https://doi.org/10.1016/j.watres.2017.02.006

Radityaningrum, A. D., Trihadiningrum, Y., Mar’atusholihah, Soedjono, E. S., & Herumurti, W. (2021). Microplastic contamination in water supply and the removal efficiencies of the treatment plants: A case of Surabaya City, Indonesia. Journal of Water Process Engineering, 43, 102195. https://doi.org/10.1016/j.jwpe.2021.102195

Shen, M., Zeng, Z., Wen, X., Ren, X., Zeng, G., Zhang, Y., & Xiao, R. (2021). Presence of microplastics in drinking water from freshwater sources: the investigation in Changsha, China. Environmental Science and Pollution Research, 28(31), 42313–42324. https://doi.org/10.1007/s11356-021-13769-x

Vercauteren, M., Semmouri, I., Van Acker, E., Pequeur, E., Van Esch, L., Uljee, I., Asselman, J., & Janssen, C. R. (2023). Assessment of road run-off and domestic wastewater contribution to microplastic pollution in a densely populated area (Flanders, Belgium). Environmental Pollution, 333, 122090. https://doi.org/10.1016/j.envpol.2023.122090



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