Team:CSU CHINA/Human Practices


Integrated Human Practices


From the lab to the real-world context, synthetic biology can benefit the world. The critical point is what it will offer and how it will blend in the existing network and serve the stakeholders. Seemingly, the process of translating scientific designs into practical products only consists of two points, namely the project and the real world, and a connecting line, which is the adaptation. But in fact, rather than a unidirectionally linear relationship, there will be dynamic interactions between the project and the world, and interpersonal effects can be dominant. As Human Practices turns to different aspects of society, we seek to engage our project with people and the real world.

To be specific, we focus on the cadmium contamination of rice with a string of questions unanswered. How high is the level of soil cadmium? Where does the cadmium come from, the soil or irrigation? What methods are usually taken to handle the cadmium pollution of farmland? What expectations should our alga live up to?

To make good for the real world, we reach out to people from various areas to integrate our algae in their workflow. We consulted experts in agriculture, the environment and medicine, took in public opinions and exchanged ideas with other teams. These efforts helped shape our design and further fostered the integration.

Construction and Administration Bureau of South-to-North Water Diversion Project

3rd Sep 2020

The South-to-North Water Diversion is a national strategic project of the People’s Republic of China (PRC), which involves 438 million people and 44.8 billion \(m^3\) of water. The Construction and Administration Bureau of South-to-North Water Diversion Project is the government department, mainly in charge of monitoring the project’s water quality under the jurisdiction of the Ministry of Water Resources, PRC.

By online meeting and phone call:

Due to a suggestion made by Pro. Yin, we contacted the Construction and Administration Bureau of South-to-North Water Diversion Project.

We wanted to consult the experts to confirm the bio-safety of the Calcium-Alginate Microbeads (Ca-Alg MBs) embedded algae. We also wanted to learn about some influencing factors of the Calcium-Alginate Microbeads (Ca-Alg MBs) embedded algae absorption efficiency during the practical application process.

Haiping Ren, the commissioner of the Water Quality Testing Center of the Bureau. He taught us some factors that may affect the adsorption of the Calcium-Alginate Microbeads (Ca-Alg MBs) embedded algae:

1. The state of Ca-Alg MBs embedded algae in the water or floating on the surface or submerged? Once the Ca-Alg MBs embedded algae are floating on the water, the Ca-Alg MBs will significantly reduce the area of contact with the water.

2. Shape of the Ca-Alg MBs. When the Ca-Alg MBs floats on the water, the spherical shape is not necessarily the shape that makes the contact area between the rubber ball and the water reach the maximum. Other rubber ball shapes, such as the six-sided body and the eight-sided body, can be considered.

3. The Calcium-Alginate Microbeads itself also can absorb cadmium, so it is necessary to measure it.

4. The Calcium-Alginate Microbeads has a certain permeability. When the permeability is low enough, it will affect the efficiency of water entering the Calcium-Alginate Microbeads.

Based on the suggestions given by the commissioner, we finally make improvements in safety and immobilization concerned. We also measured the Ca-Alg MBs’ cadmium absorbability, which you can see more in our RESULTS.

Safety and immobilization improvements:

The algae directly throw into the water will spread everywhere, and it is unable to control and capture prokaryotes effectively. We came up with the idea of using membrane filter fixtures, which can conveniently to salvage. Considering the filter’s design is not easy and put into production in significant quantities, we decided to use the most environmentally friendly and standard immobilized method: calcium alginate gel ball. The alginate gel ball is easy to preparation, diameter, easy to access data and modeling.

Also, considering the possibility of algae escaping, we improved the safety system, which you can see in our DESIGN

KAIFU Sewage Treatment Plant

Seek application layer support

To obtain the practical application evaluation and suggestion of our experimental design, we briefly described our thoughts to Ms. Jiang, an engineer from KAIFU Sewage Treatment Plants. She also led us to visit the factory.

Process Flow of Industrial Wastewater Treatment:

Process Flow of Industrial Wastewater Treatment

Current Devices and Methods:

Modified Sequencing Batch Reactor:It has the advantages of both traditional fluidized bed and biological contact oxidation. Adding a certain amount of suspension carrier to the reactor will increase the biomass and biological species in the reactor to improve efficiency. Each carrier has different biological species inside and outside. Some anaerobic bacteria or faculanoaerobes grow inside, while aerobic bacteria grow outside. In this way, each carrier is a miniature reactor, which allows nitrification reaction and denitrification reaction to happen simultaneously, thus enhancing the effect.

Modified Sequencing Batch Reactor

First Sedimentation Tank:By adding PAC and PAM, the phosphorus and most SS in the sewage are removed by coagulation, flocculation and reverse flow inclined plate precipitation. The screw pump discharges the sludge into the sludge dewatering system.

First Sedimentation Tank

Integrated settling basin:Several chemical precipitation processes are combined to remove heavy metals from wastewater in stages. The zinc and cadmium wastewater was treated by the comprehensive precipitation method, the sulfide precipitation method was used as the primary treatment, the lime milk precipitation method was used as the secondary treatment. Finally, the treated wastewater reached the national discharge standard.

Integrated settling basin

Biostyr Pre- DN:Collect early enrichment pool water, pond, and backwash wastewater and nitration biological filter backflow nitrifying liquid. As there is no air introduced in, an oxygen-free condition is formed within the filter. So the attachment in the biofilm on the filter material is mainly of denitrification of heterotrophic bacteria. Denitrifying bacteria using the raw water's carbon source will provide the quantitative of nitrate in sewage back into nitrogen to achieve total nitrogen removal.

Biostyr PDN:Receive water from pool MSBR, the filter within a lack of oxygen, anaerobic environment, so the adhesion in the biofilm on the filter material is mainly of denitrification of heterotrophic bacteria, because after dealing with the MSBR, carbon source has been in the water can't meet the needs of denitrification reaction, so need to add additional carbon source, so that the quantitative of nitrate in water will restore into nitrogen gas, and thus to achieve the total nitrogen removal.

Biostyr N:Biostyr N accepts water from Biostyr pre-DN. Due to the continuous introduction of process air, the aerobic environment is formed inside the filter. Therefore, the biofilm attached to the surface of the filter material is basically autotrophic bacteria for nitrification.

Biostyr N

ACTIFLO High Efficiency Settler: The flocculation section, flocculation section and sedimentation section are included. By adding PAC, PAM and micro-sand, the density of flocculation increases, the flocculation and flocculation effect are enhanced. Furthermore, the pollutants such as SS and TP in sewage are removed. The sludge and sludge are pumped into a hydrocyclone and separated from the sludge by a micro-sand circulation pump. The micro-sand flows through the bottom of the hydrocyclone and returns to the flocculation tank for reuse. The sludge is discharged through a submersible pump to a backwash wastewater concentrator.

ACTIFLO High Efficiency Settler

Disinfection System:Ultraviolet disinfection system and Sodium hypochlorite emergency disinfection system

Communication with an engineer of KAI FU Sewage Treatment Plants

We described our program carefully, and after listening to our introduction, Ms. Jiang advised us:

  • To consider the cost, biosafety and Cadmium removal efficiency.
  • To think about how to continuously improve the processing capacity of the process through debugging and practice in operation.
  • Consider operator training, infrastructure construction, other up-front investment, routine equipment maintenance, and waste recycling.
  • To make a good presentation of these careful considerations will make our project more compelling to relevant enterprises.

Consideration and inspiration for our program

We also improved our experimental thinking from cost, treatment efficiency, and biosafety through communication with the engineer. For instance, to reduce the project cost, we designed an environmentally friendly and energy-saving light device instead of chemical products to control engineering algae's biological activity.

Visit KAIFU Sewage Treatment Plant

Communication with an engineer in the Central Control Room of KAI FU Sewage Treatment Plant

Sewage Treatment Plant LOGO

JIN XIA Sewage Treatment Plant

Explore the basic knowledge of current sewage treatment

To understand wastewater treatment technology, we visited Ms. Liu in Changsha city’s Urban Drainage Service Center. And we paid a visit to JIN XIA Municipal Sewage Treatment Plant. Although heavy metal concentration in municipal sewage is deficient, we realized some biochemistry and physicochemical methods used in sewage. However, these methods still have disadvantages, which may lead to secondary and air pollution.

Process Flow of Municipal Sewage Treatment:

Process Flow of Municipal Sewage Treatment

Current Devices and Methods:

Fine screen:Remove the large floating objects in the sewage for the follow-up treatment’s regular operation.

Fine screen

Rotational Flow Grit Chamber: Remove the heavy sand grains for the subsequent biochemical system’s regular operation.

Rotational Flow Grit Chamber

Oxidation Ditch:①A kind of aerobic biological treatment method for organic wastewater by using suspended microbial floc.②It can remove organic matter of dissolved and colloidal states and be adsorbed by activated sludge suspended solids and other substances and remove a part of phosphorus and nitrogen. Wastewater biological treatment suspended in the water is a general name of various methods of microorganisms.

Oxidation Ditch

Anaerobic Tank:Biological phosphorus removal, water hydrolysis of refractory organic matter, and prevent the occurrence of sludge swelling.

Anaerobic Tank

Aeration Tank: The activated sludge process is used for sewage treatment. The tank provides a certain amount of time for the sewage to stay to meet the oxygen required by aerobic microorganisms and the sewage mixing conditions to thoroughly mix with the activated sludge.

Aeration Tank

Biological Deodorizer:When the odor passes through the active soil layer, microorganisms in the soil will be oxidized and decomposed. When the smell comes into contact with the breathable active soil containing many organisms, it will be entirely oxidized by microorganisms into CO2, water and microbial cell biomass to achieve the purpose of deodorization.

Biological Deodorizer

Secondary Sedimentation Tank:Mud-water separation is carried out for the mixture after biochemical treatment to ensure the effluent water quality.

Secondary Sedimentation Tank

High-efficiency Settling Tank:The high-efficiency sedimentation tank further removes NH3-N, SS, COD, TP and other indicators in the effluent from the secondary sedimentation tank through mixing, flocculation and precipitation. The process is characteristic of good flocculation effect, quick settlement separation, high surface load, good effluent water quality and high sludge discharge concentration.

High-efficiency Settling Tank

Inspiration for our project

Most of the current method for treating heavy metal effluent is to first use physicochemical methods to reduce the concentration, such as precipitating and filtering. Next, introduce a microbial membrane treatment and finally incinerate. And the whole process takes a lot of time, money, energy and land resources.

In order to simplify these complex processes into a simple process which is competent in absorbing cadium and removing Cadmium efficiently. This inspired us to design the first generation of nutritional defects symbiotic systems. The symbiotic system is composed of the bacteria that can feel the concentration of cadmium in the water and the engineering algae that can effectively eliminate cadmium.

Ms.Liu with our team members

Visit the Central control Room of Jinxia Sewage Treatment Plant

China grain reserves group Ltd. company (SINOGRAIN)

By online message:

To get through how rice moves from farmland to markets and prevent cadmium-polluted rice from entering the market, we contacted SINOGRAIN, a large state-owned critical enterprise approved by the State Council of People’s Republic of China

The relevant personnel online informed us that heavy metal testing would be carried out to ensure that the rice they purchased met the national food safety standards. According to the People’s Republic of China’s food safety standards, cadmium contamination in rice should be less than or equal to 0.2mg/kg[1].

As for cadmium-polluted rice, local governments organize the purchase and execute the disposal. The polluted rice shall not enter the food market and can only be used as industrial grain or fodder. Enterprises or farmers have no physical or chemical methods to deal with polluted grains. So, they really need an easy and efficient way of solving cadmium pollution fundamentally.

According to the 2014 National Soil Pollution Survey Bulletin, the point level of cadmium in cultivated land in China exceeds 7.0%[2], ranking first among soil pollutants in China. Cd accumulation exists in the soil in more than 11 provinces and 25 districts[3]. Cadmium polluted-soils account for 40% of agricultural soils contaminated by heavy metals, which is as high as 1.3*104hm2[4].

Through this interview with SINOGRAIN, we realize the importance of solving cadmium polluted-rice and cadmium pollution; cadmium pollution harms grain production. The unqualified grain wouldn’t make profits. According to statistics from environmental protection authorities, 12 million tons of grain is discarded due to heavy metal pollution, resulting in a direct economic loss of more than 20 billion yuan every year[5]. Farmers’ income will be affected, their enthusiasm for production will be undermined, and no one will grow grain.


  • It is feasible to study the cadmium removal of engineering bacteria.
  • Your project will provide a safe and effective way to purify water for current irrigation.
  • How to reduce costs, simplify processes and persuade farmers to use your device is a challenge.
  • Multidimensional interviews are still needed and to understand the real needs of society.


  2. 綦峥,齐越,杨红,张铁林,凌娜.土壤重金属镉污染现状、危害及治理措施[J].食品安全质量检测学报,2020,11(07):2286-2294.
  3. 刘方菁,何博,艾馨,周正海,刘顶,胡云均.大米镉污染防控研究进展[J].现代食品,2020(04):144-145+148.
  4. 刘斌,黎天勇,蔡扬尧.“镉大米”的现状、危害及修复方法简述[J].现代食品,2018(21):86-89.

Interview with Doctor Wei Luo

Associate professor, Xiangya Hospital, Changsha, Hunan

We found that cadmium pollution would seriously impact human health through literature review and relevant news reports, mainly manifested as exposure to cadmium pollution that will suffer from the itai-itai disease. To further understand the harm of cadmium on the human body and the epidemiological characteristics of the itai-itai disease, we contacted Xiangya Hospital, the most authoritative hospital in Hunan Province. Dr. Luo, the Osteonosus Department's Director in Xiangya Hospital, answered our questions about the itai-itai disease. Through the interview with Dr. Luo, we learned:

1. Itai-itai disease is a bone disease caused by cadmium poisoning. The patients will develop symptoms of osteoporosis.

2.Both acute and chronic cadmium poisoning can lead to itai-itai disease:

  • ① Acute cadmium poisoning: Most patients had inhaled cadmium ionized dust or taken cadmium - containing chemicals by mistake.
  • ② Chronic cadmium poisoning: Long-term intake of foods with high cadmium concentrations. It is easy for the human body to absorb cadmium ions but difficult for metabolism. Long-term consumption of foods containing cadmium and water with high cadmium content will lead to renal metabolic damage, loss of vitamin D, and generalized pain caused by osteoporosis.

3. Cadmium rice contamination and cadmium poisoning in drinking water are still widespread in underdeveloped areas in China.

4. When there is a regional outbreak of cadmium poisoning, the government will set up a particular hospital nearby to treat those cadmium poisoned patients.

At the same time, we learned about the diagnosis, treatment, epidemiology and other itai-itai related medical knowledge:

1.Diagnosis: Bone density test, blood biochemistry test.

2.Treatment: Exhalation, oxygen intake, and dilution of cadmium-bound red blood cells by blood transfusion.

When the patient has no significant history of cadmium poisoning, the doctor will directly diagnose osteoporosis instead of itai-itai disease.

(CSU_CHINA members interviewed Dr. Luo)


In order to understand the citizens’ cognition of cadmium pollution and cadmium contaminated rice, have a better idea of how the public perceives Genetically Modified Organisms in the context of our Clean the contamination of cadmium project, we developed an opinion survey about Genetically Modified Organisms and their use in the environmental field. We were fortunate enough to be able to spread this survey to national citizens. We received responses from almost every region and province in China.

First, we wanted to assess the sample populations general knowledge of cadmium pollution. Thus, we established several questions to learn more about their level of information. It was quite a surprise to us that 89.17% of them recognized that cadmium pollution mainly comes from soil and water.

Which of the following options do you think is the main reason for the excessive cadmium in rice?

What do you think are the current causes of irrigation water pollution?

Besides, we wanted to assess the sample population’ s acceptance when it comes to Genetically Modified Organisms application in environmental field. Thus, we established a few questions first to understand their attitude.

Synthetic biology solves energy, materials, health, environment and other issues by designing and constructing artificial biological systems that do not exist in nature. What is your attitude towards using synthetic biology methods to meet human needs?

Our project uses synthetic biology methods to artificially modify and transform Synechocystis to obtain the ability to transport cadmium, thereby absorbing metal cadmium in sewage and reducing water pollution. What is your attitude towards this method?

We performed this survey to understand more about what the public wants and needs when it comes to our project design and end users.

Interview with Pro. Juan Li

Associate Professor, College of Agronomy, Hunan Agricultural University

To learn more about the methods against cadmium pollution in agriculture, we interviewed Associate Professor Juan Li from Hunan Agricultural University.

During the conversation, we raised whether the cadmium initially comes from the soil, as Hunan Province is known as the home of non-ferrous metals. According to Professor Li, the chemical industry and geological conditions are significant offenders causing cadmium accumulation in soil.

As for methods to eliminate cadmium, Professor Li said, the feasible ones include chemical, physical and biological ways. The coplanting with cadmium-collective plants is the most applied one. Whereas biological methods, taking cadmium-absorbing endophytes as an example, are confined in laboratories and have a long way to go before the practical application.

Concerning our engineered alga, she inquired whether the accumulated cadmium kills microorganisms. She also suggested that the alga express chelation and redox proteins to be more tolerant of cadmium.

Interview with Dr. Mingdong Zhu

Researcher, Hunan Academy of Agricultural Sciences

We interviewed Researcher Mingdong Zhu from the Hunan Academy of Agricultural Sciences to further improve our design and integrate the alga with a realistic environment.

We learned that the soil cadmium concentration determines rice’s cadmium level, instead of the absolute content. Therefore, the most applied approach is impounding, which is submerge irrigation during the growth period.

Speaking of our engineered alga, Zhu advised that we should enhance the biosafety of the alga. To be more specific, the co-exist system of bacteria and algae is too tricky to be applied. He suggested we think of other ways to prevent potential leakage.

Researcher Zhu warned about the public antipathy toward transgenesis. “Certainly, there will be a considerable hindrance to the agricultural application. Nevertheless, it may exert its full potential in other fields, such as wastewater handling of tailings,” said Zhu.

Interview with Professor Yin Huaqun

Professor, School of Resources and Biotechnology, Central South University

In order to restrict our engineered algae to a specific environment and reduce environmental pollution, we designed our first-generation nutrient-deficient symbiosis system.

To further understand the application of biological cadmium removal and get professional advice, we interviewed Professor Huaqun Yin from the School of Resources and Biotechnology of Central South University. In the interview, we learned that microorganism is currently used to dispose of cadmium in the soil. As to cadmium in water, molecular materials are selected, which are faster and more efficient. Besides, Professor Yin put forward some guidance on experiment design for our project. First, we should consider how to ensure that algae absorb cadmium more than discharge cadmium. Secondly, we need to optimize the gene loop. The loop is too complex to express in prokaryote, and the efficiency needs to be confirmed. Suicide reaction from biochemical principles may give us some inspiration. It is more important to design a standard loop to solve other pollution problems. Besides, Professor Yin also gave us some guidance on ppt and presentation skills.

The interview helped us revise our experiment design. We finished our second-generation system based on the discussion and literature review: Red and blue light control system. Through simplification, we finally determined the third-generation system: The blue light regulated suicide system. (Click here for more information

Interview with Professor Yin

Rice Farmers & Farmland

Location: You county, Zhuzhou City, Hunan Prov, China

Interview purpose:

  • Learn about the status of cadmium pollution.
  • Get to know farmers' awareness of cadmium pollution, how they deal with it.
  • Moreover, learn their attitude towards our project, which helps us to further modify.


How many acres of land do you own or contract for rice cultivation? What is your family's annual income from farming?

Try to click on iGEMer and farmer to see what they said

Interview harvest:

Through interviews, we realized that cadmium polluted-rice is widespread, severe and harmful to human health. At present, farmers do not have the equipment or methods to treat cadmium polluted irrigation water, leaving cadmium sewage to irrigate farmland.

Famer’s feedback-1:

During the farm visits, farmers were worried: the toxin-antitoxin suicide system we designed needs to be started with chemical reagents. Will these chemical reagents directly put into the farm affect the growth of rice and poison rice? The farmer asks whether this system can be improved.

Our experiment improvement-1:

we changed the toxin-antitoxin system to a red and blue light control system. We could achieve the cadmium removal function of algae through the adjustment of the light, so there is no secondary pollution of the chemical reagent. Which you can find in our

Famer’s feedback-2:

After that, we revisited farmers. They can accept improved devices that use LED tubes. The portable rechargeable battery could charge directly and conveniently, which confirmed that the application of practical. Besides, the farmers pointed out that the red and blue light system is so complicated that it is difficult for them to operate and consumes a lot of power.

Our experiment improvement-2:

We gave careful consideration to the farmer's suggestion. After discussion, the third generation of blue light regulation of the suicide system has been realized. Based on the red and blue light system's tedious regulation and the low-cost performance of algae reuse, we simplified the above system, saving energy and reducing costs. Which you can find in our

Team members visited farmland

Team members learn about the irrigation water