Team:ASTWS-China/Human Practices


Human Practices

Welcome to iGEM 2021

Integrated Human Practice

Area and mode of device application

According to the domestic actual situation and policy trend, we plan to install our devices in the sewage treatment plants in the developed eastern coastal provinces.  Conventional sewage plant generally involves biological treatment process in its secondary treatment stage,  we designed a new processing flow based on this biological treatment process to treat the micro-/nano-plastics in water.

Clearer ideas of hardware device

Bioreactor design

The device can be placed in an aerobic tank and/or a secondary sedimentation tank.  In order to solve the problem of pollutant sinking and consumables replacing, we adjusted the horizontal biofilm system to vertical according to HUST2-China's suggestions, and also adjusted the rotation speed of the system to ensure the stability and degradation efficiency of biofilm.

Biocarrier design

From Engineer Bian, we got useful advice to select a combination packing. Its advantage is that it can adhere to most bacteria and has impact resistance. we controlled the speed between 30 and 35 revolutions per second to ensure that bacteria will not fall off and react normally.


More than one expert pointed out that the E. coli we use cannot be released into the environment to prevent secondary pollution. Sewage quality testing experts also told us that E. coli is one of the important indicators of water quality in sewage treatment plants. Therefore, we decided to use the existing disinfection steps of the sewage treatment plant to kill the abandoned engineering bacteria, and use their detection equipment to detect the bacterial residue in the water quality at the outlet.

Purposeful and determined science communication

We summarized the conclusions of expert interviews and questionnaires to determine the goals of science communication. We decided to promote the hazards and side effects of micro-plastics to the public and arouse their awareness of scientific use of plastics. We also plan to briefly introduce our project and eliminate people's doubts about the project. At the same time, we also plan to tell the public about the broad prospects of synthetic biology and increase their awareness and attention in this field.



Here we summarize some important gains in human practice.

1)The destructive and side effects of plastics are more serious than we thought. Many companies add chemical additives to plastic products to improve their quality. As a result, plastic products decompose into micro plastics and release toxic chemicals.

2)The environmental department pays great attention to the social significance and social value of the plastic treatment project. At present, the trend of national policy is to build a better living environment. Our projects can start in developed region, such as Zhejiang, Jiangsu and eastern Guangdong, which have greater investment in environmental protection facilities.

3)Nowadays, the actual sewage treatment facilities include swirl grit tank, primary sedimentation tank, MBR treatment, sludge conditioning tank, denitrification reaction tank, effluent, sampling room, and central control system.

4) It is a wise decision to place the device in the sewage treatment plant, because the micro-plastics are more dispersed in the natural waters, and it is easier to degrade them in the sewage treatment plant.

5) There may be some biological carriers inside the container that help the biofilm attach.  we also need to add sludge discharge and aeration device in our device, so that the sludge can leave the surface of the bioreactor faster and ensure the dissolved oxygen concentration in the bioreactor.. A standby device is needed to ensure the normal operation of the system.

6)Our degradation device should have lifting function and corresponding speed to deal with the problem of pollutant precipitation.

7)Our device should not only ensure that the micro-plastics are completely treated, but also strictly prevent the leakage of E. coli. As the water quality monitoring results of the sewage treatment plant generally lag behind the discharge, we need to increase the waste water elimination steps before drainage.

8)People have different opinions on our project of using E. coli to capture and degrade micro-plastics. Some people believe that this is a promising technology and worthy of promotion, but some also doubt the safety and efficiency of E. coli. Others believe that the technical cost of this method may be too high.

9)The public has a high enthusiasm for cooperating with waste classification and supporting plastic pollution control, but their awareness of controlling the use of plastics and standardizing the disposal of plastics is still lacking.


We collect information through public surveys, field trip and expert interviews to guide our next work. Our project this year is an improvement of the project in 2020, which requires us to further our human practice work. Our main goal is to deeply understand the background knowledge of micro-plastics, improve the technical route and improve the hardware device.

Public survey

l  Online questionnaires

The public survey was published online on the 22nd of July, 397 pieces of questionnaires were collected. Participants with different genders and diverse ages that have various educational backgrounds have taken part in the online questionnaire.



When going out for shopping or buying food, more than 40% of respondents use recyclable packages. While another majority of the public of 49.6% utilize plastic packages for convenience and a minority of 32.8% of the respondents did not care what packages they use.


There are tones of plastics wastes being generated every day. Luckily, there are nearly 80% of the respondents sort the garbage into different types as required, for the later convenience of sorting the wastes. About 20% of the respondents did not put much attention on waste segregation or even throwing the trash into the garbage can.



After the various kinds of wastes enter the garbage transfer station, they will be sorted and treated. Merely 17.4% of the public are very well acknowledged to the subsequent treatment methods of plastics wastes and 69.5% of the respondents only have the basic knowledge of the treatment methods.




In the survey, the respondents are asked the knowledge of the subsequent treatment methods for waste plastics. As predicted, most of the respondents had chosen the most commonly used methods which are decomposition, landfill and incineration. However, in the case of recycle usage, the public deem that most of the wasted plastics are recycled for secondary or multiple usage. In fact, according to authorized institution that only 9% of plastics is being recycled. This reflects the public’s ignorance of the recycling of wasted plastics.


It is widely acknowledged and admitted that the plastics cause detrimental impacts to Earth from various aspects, the respondents were asked what specific impacts are there. A majority consider that plastics will decompose into micro-plastics and harm the soil condition, threaten organisms’ healthy or even survival and will also contaminate the underground water. Only 15.7% of the respondents believe that plastics are causing damages to the sight pollution. Or, it can be interpreted that the 15.7% of the respondents might consider the sight pollution is not the prior issue.



Most of the public admit the fact that the excessive intake of microplastics have lethal affects on animals, it is arduous for the animal to distinguish plastics from food, and through the food chain, human will eventually intake the toxic plastics. The chemicals in the micro-plastics could lead to severe health issues. It is indicated that great majority of the respondents have basic understanding or are well acknowledged to the possible harmful consequences after intaking micro-plastics.




As tonnes of plastics are used and wasted annually, which have pernicious impacts in the environment and living organisms. The respondents are asked about the question of how to reduce the effects of the plastics effectively. Over 80% of the respondents believe that the reducing the usage of plastics products, using recyclable packages and active participating in trash classification are effective ways. This demonstrate that the public are conscious of how to reduce or even eliminate the destructive influences the plastics have. 



People also have different opinions on our project of using E. coli to capture and degrade micro-plastics. Some people believe that this is a promising technology and worthy of promotion, but some also doubt the safety and efficiency of E. coli. Others believe that the technical cost of this method may be too high.




Field trip

Industry status and regulations

l  Department of ecological environment of Fuyang

In order to have a more detailed comprehension of plastics pollution and the subsequent methods of dealing the plastics wastes, we attend the local ecological environment department as a field trip on the 17th of July.


We were toured within the department and were demonstrated the functions of different divisions. We also interviewed the deputy director of the department, Mr. Xiong. We are informed that there are mainly four methods that process the plastics wastes, along with their advantages and disadvantages. We also acquired basic information about the sewage treatment process and monitoring standards which built a foundational understanding for the field trip in sewage treatment company.



Sewage treatment equipment

l  Lin'an Qingshan sewage treatment Co., Ltd

On the 20th of August, our team went on a field trip to visit the sewage treatment plant, Lin'an Qingshan Sewage Treatment Plant. A staff member showed us around the company, we were introduced to the functioning treating machines and various biological treatment strategy tools. We were also notified the process of treating water which is in the frame of national regulations. We interviewed the staff member and asked for opinions to improve our project. The staff member has given valuable advices and possible impacts the E.coli might have on the environment of aerobic pool (oxic tank).


Further understanding of plastics pollution and invention of treatment device

l  Prof. Zhang, Ocean College of Zhejiang University

l  Research fieldthe effects of marine microorganisms and micro plastics on the ecological environment

Prior to the interviews, we were aware of the number of plastics produced annually around the world and the detrimental impacts of plastics pollution on whether the environment or the living organisms on the planet. However, from the interviews, we were informed several times that plastics have more destructive influences than we thought and we have concluded a more comprehensive understanding of the effects of the pollution. Many companies add chemical addition agents to the plastic products to enhance their quality, the chemical additions, however, are toxic after the products decompose into micro-plastics. Thus, the toxic microplastics might flow into water bodies or into the soil and the aquatic or terrestrial organisms would accidentally ingest the poisonous chemicals and die due to suffocation or other health issues. Another example is that the micro-plastic that flows on the surface of water bodies might block the sunlight which the aquatic animals live under the water cannot absorb enough sunlight, especially the phytoplankton, this could have pernicious impacts on the survival of aquatic organisms. Eventually, through the food chain, the lethal effect return back to human whom produced plastics at the beginning. The human may ingest animals that contain microplastics in their bodies. The presence of microplastics in human bodies leads to irreversible impacts. Microplastics release toxins, those toxins enter the digestive system, lymphatic system, immune system, and different organs. The impacts could not be detected immediately, it is a long-term and potential consequence.

Professor Zhang also introduced the relevant treatment devices containing microorganisms that degrade pollutants, and approved our plastic capture & treatment device. She also suggested that it is a wise decision to place the device in the sewage treatment plant, because the micro-plastics are more dispersed in the natural waters, and it is easier to degrade them in the sewage treatment plant.


Improved design of hardware device

l  HUST2-China iGEM 2021 team

According to the previous investigation results, we designed the primary engineering bacteria device, and the core of the device is the intermediate reaction device containing engineering bacteria. When the polluted water enters the reaction part, we will block the discharge point of the water outlet with a sheet to degrade the PET micro-plastics in the sewage. The design of the rotating device also helps to improve the reaction rate and achieve the maximum possible degradation.

Subsequently, we encountered practical problems, such as how to solve the problem of pollutant sinking during treatment. We got the help of Qilong Lai from HUST2-China. He suggested that our reaction device be designed as a lifting device, which not only solves the problem of prolonging the reaction time caused by pollutant sinking, but also makes it easy to replace consumables.



Sewage treatment system and related processing technology

l  Mr.Bian, Zhejiang Wenhan Environmental Technology Co., Ltd.

l  Research fieldWastewater treatment technology and engineering construction

The sewage treatment system can be considered as one of the most essential aspects that are related to our project. We are informed that there are multiples technologies used in sewage treatment and the various indexes had to be accomplished to successfully treat the sewage, for instance, one of the technologies is ‘Special membrane separation technology'. From the interview with Mr.Bian, we acknowledged that the first steps to deal with the sewage are ‘coagulation’ and ‘precipitation’, the purpose of these processes is to separate large particles from the sewage. With the additional usage of biochemical tank tools, anaerobic tanks, and aerobic tanks, the mud and the water are able to be stratified, and the water quality will then be detected.

According to Mr.Bian, the indexes that will be checked mainly include ammonia, COD, total phosphorus. Within the national regulated frame, all the sewage treatment companies adhere to the regulations. Additional to the three indexes, the pH, the amount of dissolved oxygen, and the color of the treated sewage were also taken into consideration, as well as the heavy metal substance that is carcinogenic. In the interview with the expert, MBR technology was mentioned. Membrane bioreactor (MBR) is where a perm-selective membrane is integrated with a biological process. Mr.Bian demonstrates that the usage of MBR technology can replace the role of the secondary sedimentation tank with high enfficiency and low cost. The separation of solid and liquid can be done through the membrane, the advantages of the technology is that the holes on the membrane can be adjusted to 0.01 micron which is effective to filtrate solids.

In view of the idea that we want to carry the bioreactor on a substrate similar to MBR membrane, Mr. Bian said that we need to add sludge discharge and aeration device in our device, so that the sludge can leave the surface of the bioreactor faster and ensure the dissolved oxygen concentration in the bioreactor. He also proposed that we need to prepare a standby device. When the microbial flora of the bioreactor is damaged, the standby device can be started to ensure the normal operation of the system.


In depth understanding of water quality monitoring of sewage treatment plant

l  Director Song Bai, Yunnan Liangshan Environmental Protection Co., Ltd

l  Research fieldAutomatic control system of sewage treatment plant, water quality analysis and monitoring system

In the sewage treatment plant, the water quality of three places should be monitored. The first place is the intake. Cod, ammonia, nitrogen, total phosphorus, total nitrogen and pH value of domestic wastewater shall be monitored. If the source is industrial wastewater, the indicators of heavy metals, such as cadmium, lead, arsenic, mercury, etc., may be added as appropriate. The second place to be monitored is the production process. Generally, dissolved oxygen, sludge concentration, pH, nitrate nitrogen and orthophosphate should be monitored. The third position is the discharge outlet, which shall be carried out according to the national sewage discharge standard. It is also used to monitor cod, ammonia, nitrogen, total phosphorus, total nitrogen, pH, heavy metals, etc.

Our project needs to ensure the vitality of E. coli in the bioreactor in the sewage treatment process. Mr. Bai pointed out that the system used to monitor the water quality in the production process can assist in detecting the survival indicators required by some engineering bacteria. However, he pointed out that the use of E. coli for micro plastic treatment requires the addition of sterilization steps after the end of the treatment process. This is in line with our design - we plan to install the device in the sewage treatment plant and use the disinfection device of the sewage treatment plant to disinfect the water flowing through our device.

In response to Mr. Bai's reply, we further inquired about the process of detecting E. coli at the discharge outlet of the sewage treatment plant. He gave a very important information: the routine step of checking the water quality at the water outlet is to take water samples at the water outlet and send them to the laboratory for test. Generally, the test results are lagging. This suggests that we still need to ensure that all residual engineering bacteria are killed before sewage discharge.

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