To gain a deeper understanding of the importance of addressing Hexavalent Chromium pollution, our team conducted extensive research on the issue. This included investigating the health consequences associated with Cr(VI) exposure, reviewing pollution incidents, understanding current situations in China, interpreting case studies, examining existing national and international regulatory policies, and studying current remediation methods of the pollution.

Health risks:

According to studies, exposure to Hexavalent Chromium poses unacceptable carcinogenic risks for all age groups, with more destructive impacts on children due to their lower body weight.

Studies done on animals have shown that oral exposure to Cr(VI) compounds can lead to tumors in the forestomach and intestines. Moreover, intake of contaminated water led to a significant increase in the incidence of squamous cell carcinomas or papillomas in the oral mucosa or tongue.

In addition to carcinogenic impacts, Hexavalent Chromium also leads to other forms of health problems. High exposure to lethal or near-lethal doses of Cr(VI) compounds can lead to severe gastrointestinal effects such as abdominal pain, vomiting, gastrointestinal ulceration, hemorrhage, and diarrhea. Based on animal studies, Cr(VI) is also toxic to fertility and prenatal development.

Exposure to cr(VI) can have long-lasting effects on health. Studies find that chromium concentrations increased in the skin of Cr(VI)-exposed mice, suggesting potential impacts beyond the initial point of contact.

Past pollution incidents:

In 2011, Yunnan province experienced a major environmental crisis regarding hexavalent chromium pollution.

Local residents recalled, "The goats are dead, the pigs are dead, and you can't drink the water."

The source of contamination was 5000 tons of untreated chromium slag that had been illegally dumped into the mountains and the Nanpan River, at the source of the Zhujian River. Cr(VI) concentrations in water were found to be 2000 times above the permitted level.

The Xinrong village, the nearest village to the source of pollution, suffered devastating damage. Following the incident, 77 livestock died shortly after drinking the contaminated water, and years later, at least six residents were reported to have died of cancer.

Local government authorities quickly responded to assess the situation. To remediate the contamination, sodium metabisulfite was applied to convert Cr(VI) to Cr(III), and alkali was added to neutralize the water's acidity. Moreover, mud from the polluted river was excavated, treated, and then baked into bricks for regular use.

This contamination incident demonstrated the devastating social, environmental, and health impacts of hexavalent chromium.

Current situations:

According to two separate research datasets, 14 groundwater samples collected in Weinan city, and 36.67% of samples collected from the Changguanmiao Village and Miaogou Village had chromium concentrations exceeding the safe limit.

Regulations:

According to China’s National Standard for Drinking Water Quality (GB), the maximum permissible concentration of hexavalent chromium (Cr(VI)) in drinking water is 0.05 mg/L (50 μg/L) USDA Apps. Moreover, the NSF P535 certification protocol explicitly includes Cr(VI) among the contaminants to be reduced—ensuring performance and safety of filtration products under local regulatory expectations 

Methods:

There are many methods of remediation approaches for Cr(VI) now. Firstly, physical methods such as adsorption, filtration, and ion Exchange. Secondly, chemical methods such as reduction and precipitation. Thirdly, biological methods such as bioremediation, biosorption, and electro-bioremediation. These methods are applied based on the situation, and are often utilized integratedly.

Survey Data & Analysis
In order to assess public understanding of Hexavalent Chromium (Cr(VI)) pollution and its associated health risks, our team distributed a survey and received 652 valid responses. The findings provided insights into awareness levels, concerns, and attitudes toward environmental contamination and remediation efforts.

Participant Demographics

Figure 3 Age distribution of participants.

We found a total of 652 participants for our survey. Age is evenly distributed across age groups, with the biggest age group being 18-25, which corresponds to the major of social media.

Figure 4 Participant awareness of Cr(VI) in general.

Most participants had never heard of Cr(VI) (69.48%) or only had a faint impression without a clear understanding its function and environmental impact (23.32%). Fewer than 10% acknowledge Cr(VI)’s uses, harms, and current situation, which highlights the need for stronger education on heavy metal contamination, especially under China’s rapid modernization and industrialization circumstances.

Figure 5 Participant awareness of Cr(VI)’s usage in industrial production (A) and its environmental impacts (B).

Electroplating and dyes were the most commonly recognized functions of Cr(VI), followed by its use in corrosion inhibitors, leather tanning, and wood preservatives. About 13.07% of participants were not familiar with any industries using Cr(VI).

Approximately 65% of participants were aware of Cr(VI)’s carcinogenic and environmental pollution effects, followed by other health-related impacts such as respiratory difficulties and reproductive or developmental toxicity. Meanwhile, 12.56% of participants were unaware of any harms posed by Cr(VI). Notably, we discovered that many of those participants also belonged to the 13.07% who are unfamiliar with its functions.

Figure 6 Participant attitude toward Cr(VI) treatment using public resources (A) and business products (B), as well as their opinions toward using living organisms in these methods (C).

We asked participants about their attitudes toward addressing Cr(VI) contamination through using public resources or relying on businesses, the latter involving higher product prices. Responses of strong opposition, moderate opposition, or unsure remained consistent across both questions. However, more participants tend to remain neutral when they were asked about business, and in overall, fewer participants supported business efforts relative to public efforts.

We also examined the participants’ opinions on biological treatments that require living organisms such as bacteria. A significant portion (36.66%) of respondents chose a neutral stance on biological treatments, and the number of participants comfortable with the usage of living organisms slightly surpassed the number of participants

Figure 7 Participant awareness toward the different types of heavy metal contamination treatment.

We also investigated the participants’ knowledge of different types of treatments to Cr(VI) contamination. 54.27% of participants have heard of chemical restoration, followed by biological and physical treatment. It is also notable that 32.66% of participants are not aware of any of these methods.

Figure 8 Participant ranking for priorities

when determining the methods for Cr(VI) decontamination. For ranking questions, the average comprehensive score of each option is automatically calculated by the Wenjuanxing system based on the ranking results of all respondents. It reflects the overall ranking position of the option: the higher the score, the higher the overall ranking. Average comprehensive score of an option = (Σ frequency × weight) ÷ number of respondents Weight is determined by the position in which the option is ranked. For example, if there are 3 options to be ranked, the first position has a weight of 3, the second position a weight of 2, and the third position a weight of 1. The score depends on the number of options. For example, if there are 3 options, the weight for 1st place is 3 points. If there are 30 options, the weight for 1st place is 30 points. This score is not affected by the setting “Please rank * items.” If the ranking question options are quoted from a previous multiple-choice question, then the weight for 1st place equals the number of options in that multiple-choice question.

We asked participants to determine their priorities when evaluating whether a treatment method is worth implementing, with higher scores indicating higher priority. Safety and non-toxicity is the participants’ top concern, surpassing the second most important factor scientific evidence by 0.43 and cost-effectiveness by 0.51 points.

Figure 9 Participant knowledge toward the synthetic biology discipline

Additionally, we hope to investigate the participants’ knowledge about the discipline synthetic biology. 42.48% have never heard of this field or knowledge, while a similar number of participants have only heard of it briefly. Synthetic biology remained an underrealized curriculum, and greater efforts are needed to strengthen the perceived importance of this field among the public.

What We Learned & How would This Influence Our Project

From this survey, we learned that public awareness of Cr(VI) and its environmental and health impacts remains limited to a small group of people, with the majority of participants having little to no prior knowledge of the subject. Most of the participants were younger participants more adaptive to social media and other modern advancements, providing them more timely access to information. Yet the majority of these participants are also unaware of Cr(VI) contamination, demonstrating the urgent need for increased publicity of the environmental issues we currently face worldwide. Our investigation into participants’ knowledge of the benefits and harms of Cr(VI) suggests directions for future educational attempts: by emphasizing the functions and impacts of Cr(VI) that are already more widely known, we can help people connect to our project to what they are familiar with. At the same time, the investigation also highlights the lesser known effects we could promote more; also, the synthetic biology discipline should be emphasized more in education too. When asking participants to express their attitudes toward business-led efforts with increased pricing, less participants choose support and instead turned to neutral, demonstrating pricing as a determinant of participant acceptance. Moreover, when evaluating treatment priorities, participants emphasized more on factors such as safety and non-toxicity and scientific evidence, showing a strong preference for health protection and authority. It is also worthy to note that most participants are neutral or supportive of the usage of organisms in treatment, which becomes an advantage for our treatment.

Stakeholder Intro

We arranged an online meeting with Dr. Bao. Dr. Bao is a biosafety expert mainly engaged in research in the fields of global governance, emerging technology governance, and biosecurity. He received his PhD from the School of Public Policy and Management of Tsinghua University. We aimed to supplement our knowledge about the advancements and limitations in previous methods to eliminate heavy metal contamination as well as public attitude and knowledge toward purifying water, especially using biological methods, believing Dr. Bao’s expertise could guide us in perfecting our product and promote knowledge about the urgent need for combatting heavy metal contamination.

Figure 10 Participants: Dr. Bao, Jasmine Cao, Liris

Interview notes

Dr. Bao accentuated that the effects of heavy metal contamination is not limited to water resources: soil, aquatic plants, and aquatic animals are all subtle to bioaccumulation since they come in direct contact with the contaminated water resources. Therefore, humans are affected by these particles not only through drinking but also through consuming food and using products related to these mediums, exemplifying biomagnification. We could use this information to increase public awareness and consider whether our product tends to the materials in contact with contaminated water.

Dr. Bao also stresses that the public might be apprehensive about certain methods of treating contamination using bacteria, depending on whether they perceive the heavy metal as truly threatening. He mentions that in previous crises, such as the 2011 Yunnan Cr dump in reservoirs and the 2012 discovery of Cr presence in capsules, the public increasingly focused on knowledge about heavy metals.

We also discussed existing methods of water treatment. For instance, chemical methods, such as adjusting pH or converting Cr(VI) into less harmful ions, are highly effective for responding to sudden contamination crises that require short-term treatment. Physical treatments including adsorption and membrane separation are also widely used. Biological methods, such as using plants to extract ions, provide relatively low costs but lack the ability to respond to emergencies quickly. Thus, a biological approach that improves efficiency and further reduces costs would be highly favored.

Stakeholder Suggestions

Bao notes that with our current hardware, water treatment may require extracting water for processing in factory equipments rather than treating entire bodies of water directly. He emphasized that our team need to have a clear perception on the places where we could implement our product.

Dr. Bao believes that it is infeasible infrom the public about Cr(VI) and none else; rather, we should aim to promote the harm of heavy metal pollution in general.

Suggestion & inspiration implementations

Applying Dr.Bao's interview with our projct, our team collectively made this agreement: if we aim to promote our product in a period without an ongoing contamination emergency, it would be important to raise general awareness of bioaccumulation and biomagnification in the public, particularly their effects on growth and inheritance, in order to prevent problems relating to the public lacking knowledge of potential threats they may face contacting with hexavalent chromium. At the same time, we decided to enhance public awareness about contamination and pollution of hexavalent chromium along with other heavy metals. Environmental and biological knowledge, such as bio-accumulation, will also be a focus of our educational attempts.

Stakeholder Intro

Dr. Wang Dongfeng is the Associate Chief Physician at the Wuhan Petrochemical Hospital Physical Examination Center, PhD from Wuhan University in 2011 and previously served as a university lecturer. We consulted with Dr. Wang on the health hazards of Cr(VI) and hoped to find advice on their prevention and treatment.

Figure 11 Participants: Dr. Wang, Alvin Li, Jasmine Cao, Rika Hayashi

Interview notes

Dr. Wang Dongfeng highlighted several health risks associated with Cr(VI) exposure, including skin cancer, chromium ulcers, altered red blood cell volume and hemoglobin levels, anemia, gastrointestinal symptoms such as diarrhea and vomiting, increased risk of stomach cancer, pulmonary fibrosis, developmental delays, and liver necrosis. He also mentioned some cases of Cr(VI) exposure he has met in his career, mentioning seeing two cases of severe chromium poisoning. He listed two cases of chromium exposure events. The first case is a worker in 2017 with poor protective equipment suffering a 4 mm nasal septum perforation, treated with skin grafts and growth factors, and the other individual was chemically burned by chromium salts, eventually requiring extensive emergency treatment to prevent potentially fatal outcomes.

We also discussed the potential pathways to chromium exposure. Dr. Wang mentions that many occupations involving metal frames, chromium mining, and leather softening require the usage of Cr(VI). Additionally, residents near factories are also in contact with chromium, including printing factories, leather factories, steel welding sites, glaze/ceramic coating facilities, electroplating factories, open chromium dumping sites, and many others; the abundance underscores the urgent need for treatment of Cr(VI). Other items we use in daily life might also contain chromium. Leather products, pigments, and cosmetics contain a lot of chromium and other heavy metals. As a doctor, Dr. Wang also assures us that chromium exposure is a minimal threat to the environment. We are able to gain specific measures of the current Cr(VI) concentration in the drinking waters we encounter every day and regulations about chromium densities. That data allows the public to be more confident and accurate when we make related claims about water contamination severity.

From this interview, we confirmed that different concentrations of Cr(VI) lead to distinct magnitudes of health hazards, which highlights the importance of our product’s capability to measure Cr(VI) concentration accurately. Dr. Wang’s cases illustrate that exposure can result in a huge variation of health consequences; while we understand that we must be cautious in how we present this information, we see value in publicizing general risks of Cr(VI) contamination to raise awareness about preventive measures, a constructive way to engage the public in the fight against pollution.

Stakeholder suggestions

Dr. Wang expressed admiration for our project’s attempt to measure the concentration of Cr(VI) in our project, as differences in Cr(VI) would lead to different levels of danger. When being asked about potential ways to implement Cr(VI) treatment methods, he thought of an innovative solution—to use a negative-pressure chamber with honeycomb-shaped structures that capture Cr(VI) contaminated dust and react it with reducing agents to lower dust pollution in machinery rooms. Moreover, He is optimistic about the future development of chromium contamination treatment, noting that China, as a leading industrial power with a fully developed industrial chain, will inevitably see increased Cr(VI) use in sectors like aerospace, defense, drones, and robotics, yet he trusts that companies will follow regulations, provide education and protective equipment for workers, and strengthen safety awareness of the public. Consequently, he expects fewer victims of Cr(VI) contamination in the future. His insights bring us to consider the wider scope, the country’s entire industrialization process and how innovation should, and probably would, be associated with increased public awareness.

Suggestion & inspirations Implementation

In further steps of our business plan, team Crouton will consider Dr. Wang's ideas as new projects to research and develop. As Dr. Wang states that Cr(6+) pollution is merely detectable, we decided to remove our ideas about expanding our product's market to medical organizations and hospitals. Our consultation led us to be more careful when using Cr(VI)-contaminated water in the laboratory; now, we are placing more emphasis on double-checking leakage and containment and using appropriate personal protective equipment.

Current methods to remediate Hexavalent Chromium pollution mainly focus on reducing hexavalent chromium to trivalent chromium, although there are a variety of mechanisms to achieve this. For example, applying sodium metabisulfite as a reducing agent is a common treatment for wastewater. In further treatment, after Cr(VI) is reduced to Cr(III), sodium hydroxide is added to precipitate Cr(III), and the solid is removed using the polymer flocculant polyacrylamide to avoid re-oxidation to Cr(VI) under alkaline conditions.

-Government Regulations and Risk Management, including preventing the spread of contamination from unremediated sites and promoting risk management.

Stakeholder Intro

Dr. Huang is the Director of Shanghai Hongqiao Wastewater Treatment Plant, with over many years of experience in industrial and municipal wastewater treatment.

Figure 12 Participants: Dr. Huang, Rachel Zhao, Amy Hong

Interview notes

1. Reception of Wastewater

The professor explained that sewage treatment plants usually receive wastewater from enterprises through coordinated scheduling, which allows transportation within a small regional range. Before the wastewater is turned in, sodium and chromium densities is carefully monitored. The wastewater is then delivered to the plant via a pipeline network.

2. Treatment Methods

According to the professor, sewage treatment plants employ several treatment methods, including activated physical methods, the A²O biological process, disinfection tanks, sedimentation, and biological treatment systems. When asked about hexavalent chromium, the professor noted that while physical methods can be discussed in theory, the plant primarily relies on chemical or biological processes for its removal rather than strictly physical methods.

3. Operational Challenges in the Plant

The professor identified influent water quality fluctuations as the greatest operational challenge for the plant. To address this, the plant relies on intelligent monitoring and regulation. Geological and operational data are collected to achieve comprehensive control. High-power equipment is managed to regulate electricity consumption, while chemical dosages are automatically adjusted to stabilize effluent quality. However, the professor cautioned that extreme conditions may sometimes push the systems toward their operational limits.

4. Reusage of Treated Water

The professor explained that reclaimed water is primarily used for ornamental landscapes and for raising fish in scenic areas. When water volumes increase significantly, sludge accumulation can occur. To address this issue, the plant uses water-source heat pumps for heating and relies on microorganisms to support sludge management. The professor emphasized that the conventional treatment methods used at the plant do not negatively impact the environment. On the contrary, the treated water is often of higher quality than normal water.

5. Risks in Treated Water Reusing

When discussing potential risks, the professor noted that there are essentially no major concerns in the reuse process. This is because the wastewater must already meet 100% compliance standards before entering the plant. As a result, risks such as microbial residues or heavy metal exceedances are not viewed as significant, and no additional processes were identified as necessary.

6. Existed Biological Approaches During Treatment

The professor confirmed that biological treatment methods are already in use at the plant. For example, bacteria such as nitrifying and denitrifying organisms are applied to transform pollutants. He did not express concerns about extending biological approaches to target hexavalent chromium removal in the future.

7. Approvals and Permits used in the treatment plant

The professor explained that, during the plant’s construction, permits for pollutant discharge and building were obtained. As a management entity, the plant must receive approvals from both the Environmental Ecology Bureau and the Water Affairs Bureau. If chromium contamination were to occur in the future, any new treatment methods—whether chemical or biological—would also require such approvals.

Stakeholder suggestions

In reflecting on the project, the professor highlighted both its potential value and its challenges. On the one hand, he recognized that a chromium-targeted product could enhance treatment capabilities. On the other hand, he pointed out that real wastewater often contains multiple heavy metals, not just chromium. Therefore, when developing the product, it is necessary to take into account the survival ability and functional effectiveness of bacterial strains in various water sources. He suggested that the current product may be too narrow in scope, which could limit its broader application. He also stressed that influent pollution varies depending on the source, and for this reason, he recommended extending the experimental cycle, since the effectiveness of bacterial strains may change over time.

Suggestion & inspirations Implementation

We will collect several wastewater samples from different factories and conduct stability tests on our engineered strains, adjusting the strain ratio and nutrient supply based on results in the future. Also, in response to Dr. Huang's feedback on the detriment of hexavalent chromium pollution, we will actively organize and hold targeted education sessions. 

Stakeholder Intro

Shan Huimei, Professor, Ph.D., Advisor for Master's and Doctoral Students, Pingfeng Scholar. Her reasearch directions include groundwater pollution and harms prevention, polymeric composite materials for environmental remediation, environmental impact assessment, modeling of pollutant geochemical behavior. Her educational experiences include graduating from China University of Geosciences (Wuhan) with a Bachelor of Engineering in Environmental Engineering. She graduated from Huazhong University of Science and Technology with a second Bachelor of Engineering in Architecture. She graduated from China University of Geosciences (Wuhan) with a Ph.D. in Engineering, specializing in Groundwater Science and Engineering.

Occupation:

December 2012 to January 2014: Joint Ph.D. training at the Pacific Northwest National Laboratory (PNNL), U.S. Department of Energy.

Figure 13 Participants: Alvin Li, Rachel Zhao, Amy Hong, Joyce Han, YaXuan Cheng, Austin Jiang, Jacie Liu, Grace Lin, Elaine Zhou, Liris Zheng, Rika Hayashi, Huimei Shan.

Interview notes

Current Academic Research Priorities on Heavy Metal Water Pollution

One major research direction focuses on remediation methods for heavy metals present in water. Common methods include adsorption, redox reactions, and the use of coagulants. Mainstream Solutions for Degrading Hexavalent Chromium include converting Cr(VI) into trivalent chromium (Cr(III)), which is less toxic. Coagulants are then added to precipitate and remove Cr(III). Another deeply investigated method involves adsorbents, which can capture Cr(VI) and convert it into Cr(III) simultaneously. Meanwhile, scientists are striving to reduce costs while improving removal efficiency.

Another line of research examines interactions between heavy metals and emerging pollutants such as microplastics. For example, researchers are investigating whether the degradation of microplastics may induce additional changes in heavy metals.

A third direction concerns soil contamination. If polluted water is used for irrigation, the soil becomes contaminated as well. Moreover, heavy metals may further react with soil, causing additional impacts.

Pros and Cons of Different Degradation Methods

When asked about the strengths and weaknesses of chemical or physical degradation methods, Professor Shan emphasized that chromium treatment today rarely relies on a single approach. Instead, chemical, physical, and biological methods are usually combined.

Cost of Treating Heavy Metal Water Pollution

The cost of degradation depends heavily on the specific method used. The choice of material significantly influences expenses. For instance, using activated carbon or calcium-based chemicals tends to be relatively inexpensive. Currently, scientists are actively searching for cheaper and more effective materials.

If iron salts or waste slag are proposed fro cleaning water. Treatment costs also vary depending on the type of wastewater, since different sources contain different concentrations and types of pollutants, requiring tailored approaches. For these reasons, the cost of treating heavy metal–contaminated water varies widely.

Impact of Cr(VI) Degradation on Local Residents

Professor Shan stressed that removing Cr(III) is just as critical as reducing Cr(VI). Although Cr(III) meets national water quality standards, it should not be left in the water source; it must be fully precipitated and removed. This is because Cr(III) can be oxidized back into toxic Cr(VI) under natural conditions. In short, complete removal of all chromium species is essential to ensure safe water quality and prevent health risks.

Impact of Cr(VI) on Food Safety

In reality, the impact of Cr(VI) on food safety is rarely discussed. Compared with other elements such as cadmium (Cd) and arsenic (As), chromium is more mobile and therefore less likely to accumulate in crops.

Severity of Cr(VI) Pollution

Hexavalent chromium pollution is extremely severe. Most industrial processes produce toxic Cr(VI), meaning the majority of industrial wastewater contains chromium. Due to Cr(VI)’s strong mobility and toxicity, and because current treatment methods cannot reduce chromium concentrations to safe levels at low cost, chromium pollution remains a widespread and serious problem.

Public Awareness of Cr(VI) Pollution

Public awareness of chromium pollution is much lower than for other types of pollution. Despite chromium pollution being more widespread and severe, very few people pay attention to it, and overall understanding remains weak.

Stakeholder suggestions

Professor Shan emphasized the critical importance of removing Cr(III) from the water source, claiming that even though Cr(III) meets national water quality standards, it should not be left in the water source because it can be oxidized back into toxic Cr(VI) under natural conditions. In short, complete removal of all chromium species is essential to ensure safe water quality and prevent health risks.

Professor Shan also highlighted the need to raise public awareness on our topic. Hexavalent chromium pollution is extremely severe. Most industrial processes produce toxic Cr(VI), meaning that the majority of industrial wastewater contains chromium. Due to Cr(VI)’s high mobility and toxicity, and because current treatment methods cannot reduce chromium concentrations to safe levels at low cost, chromium pollution remains a widespread and serious problem. Nevertheless, public awareness of chromium pollution is much lower than for other types of pollution. Despite chromium pollution being more widespread and severe, very few people pay attention to it, and overall understanding remains weak.

Suggestion & inspirations Implementation

Implementing Professor Shan's stress on the removal of Cr(III), we added a precipitation and filtration chamber in our hardware system to fully filter and remove the chromium content in water. In our revised system, after Cr(VI) in the water is degraded into Cr(III), sodium hydroxide (NaOH) will be applied to precipitate Cr(III) in the water into solid. Finally, the water will be filtered to remove impurities and the precipitated chromium, completely removing the remaining Cr(III).

In response to Professor Shan's response regarding the public awareness of Hexavalent chromium pollution, we actively held education sessions, aiming to spread information on our topic.

Stakeholder Intro

Mr. Sun, the chief engineer and Mr. Xu, the director, of the environmental monitoring station of the Yangpu district of Shanghai, China have accepted our interview.

Figure 14 Participants: Mr. Sun, Mr. Xu, Alvin Li, Amy Hong, Rachel Zhao

Interview Notes

1. The monitoring frequency for chromium pollution

Professor Xu regarded that there are no fixed schedules for testing. Instead, the tests are conducted based on the quality of the water body, government regulations, and other external factors.

2. Plausible circumstance for the product

Because the safety of our bacteria will be a major consideration, the professor suggested our product will be more effective when cleaning industrial wastewater and other types of human-generated sewage. The professor dislikes the idea of putting our bacteria into the groundwater. Because as soon as the bacteria are released into the water bodies, it is almost impossible to clean them out. Besides, groundwater is a highly protected resource, and it is unlikely to be polluted by chromium or other heavy metals. Therefore, the application of the genetic strand is most suitable in the electroplating industry, where most chromium pollution occurs.

3. Victims of the pollution

When we asked the professor if the diffusion trend of chromium pollution in different environments affects nearby ecological systems, the professor noted that the pollution mainly affects humans, as heavy metals tend to deposit in the bodies of animals and will eventually end up in the human body. The professor said most heavy metals will get diluted and will not be dense enough to cause harm to the ecosystem and the marine ecosystem.

Stakeholder suggestions

Professors Xu and Sun both raised valid concerns regarding possible issues that could arise in our product. He initiated the idea that employing bacterial remediation methods might not be the most ideal in many cases due to the possibility of bacterial fluid leaking into surrounding areas, which may pose secondary contamination and cause additional issues, such as excessive E. coli concentrations in groundwater or local water sources, causing problems for both people and ecosystems near the treatment area. Our product should be continuously compared with existing, more mature methods in the market, in order to improve our current product as well as the rate of degradation or detection of our product compared to other existing products, which will allow us to provide more reliable data that demonstrates our product's efficacy.

Furthermore, Professor Xu noted that for our results to be the most accurate and the most reflective of actual wastewater quality, we should use some actual wastewater released in particular areas of Shanghai. He recommended several locations and company sites that our team could request and collect wastewater samples.

Subsequently, Professor Xu pointed out an important flaw within our product, which is that existing wastewater samples could have already been blue in color before the addition of our detection E. coli, making our hardware unable to determine the exact concentration of Cr(VI), if any. Sediments and pollutant particles that are relatively larger in size could also affect our outcomes negatively, and these issues must be addressed immediately to ensure that our product works properly.

Suggestion & inspirations Implementation

Due to Professor Xu voicing these concerns, we've decided to implement the relevant changes to our product in an attempt to solve these issues. Firstly, we've made sure to include substantial UV light systems throughout our hardware, especially in the Detection and Degradation Chambers, where the bacteria will be performing their functions (refer to business plan and hardware sections for specifics). After they've completed their functions, they will be killed immediately by the bacteria, and the liquid will flow to its respective directions, either to the Waste Collection Zone (for the Detection bacteria) or the Final Filtration Zone (for the Degradation bacteria). These various UV light systems and controlled confinement of bacteria ensure that the chances of bacterial fluid leakage are at a minimal level.

As for the issue of blue light detection, we've decided to monitor our hardware system so that a substance that turns industrial sewage transparent will be added to the testing section before the light detection sensor activates. Our sensor has been modified to only detect the wavelengths for blue visible light, and through substantial testing, the respective changes in intensity will thus indicate a specific concentration of Cr(VI) present in the sample.

In the future, we would still hope to conduct more testing and hopefully manage to secure some samples from the locations listed by Professor Xu, and hence improve our product even more, aiding it to work in different, specific environments.

In China, the water and sewage treatment market, particularly concerning Hexavalent Chromium (Cr6+), is marked by rapid technological advancement. The demand for frontier water treatment technologies has increased due to tightening environmental regulations. Companies like Evoqua Water Technologies (now part of Xylem) offer a broad portfolio of filtration, disinfection, and water reuse solutions, supported by strategic collaborations with partners like Aquatech, Sinopec, and Beijing Originwater Technology. Meanwhile, innovation within China is thriving: for example, Zhen Ding Tech Group, a Chinese electronics manufacturer, leveraged Evoqua’s Magneto® anode technology to upgrade electroplating processes, reducing wastewater output by millions of gallons and significantly curbing metallic waste.

Advanced treatment methods and cost structures are also evolving. Recent patent applications indicate a rise in R&D aimed at reducing sludge production, pollutants reusage, and ultra-low emissions in Cr-containing wastewater treatment. While precise cost data for Chinese enterprises remains unclear, global prices are not the case: Advanced Oxidation Processes (AOPs)—sometimes adopted in combination with other technologies—carry high price tags, with capital costs often exceeding USD 3–4 million for systems treating around 0.42 ML/h, and operating expenses reaching USD 0.15–0.30 per m³. Though these figures may be higher than typical Chinese implementations, they signal the investment required for cutting-edge, effective treatment.

Mr. Zhang Andong, also known as Anthony Zhang, is an experienced investor who invests in projects aimed at sustainable development and environmental preservation.

Figure 15 Participants: Mr. Zhang Andong, Alvin Li, Yaxuan Zeng

Interview Notes

Current Industry Details

We inquired about the current percentage of companies’ operating costs associated with treating wastewater containing hexavalent chromium and learned that it largely depends on the company's size. Large enterprises have a slightly lower percentage, around 3~8%, as their output and income are both exceedingly high, and they have more experience dealing with wastewater treatment systems, thus investing earlier in more reliable treatments. Middle or smaller enterprises conduct fewer investments, and their economies of scale are far lower, so their treatment systems tend to be slightly behind, with the percentage around 10~20% or higher, of their total revenue. The latter enterprises also tend to use older treatment methods, like chemical precipitation.

Thus, we continued to ask about the common treatment methods, and concluded that two tend to be implemented most often. Firstly, chemical reduction, where under acidic environments of pH 2~3, a reducing agent is added to convert Cr6+ to Cr3+, as Cr3+’s toxicity is lower than that of Cr6+, and this agent could be ferrous sulfate (FeSO4) or sodium metabisulfite (Na2S2O5). Yet, this method consumes large quantities of reducing agents, and the accumulation of salts may affect its overall reduction efficiency, causing it to be unstable. The yearly operational costs of this method are around 80~250 thousand RMB for the reducing agent, and 150~500 thousand RMB for sludge treatment, under the circumstance that around 50~200 tons of wastewater is treated daily. For smaller enterprises, the total costs may be around the range of 350 thousand to 1 million RMB per year.

Secondly, there is the chemical precipitation method, where under slightly basic environments of pH 8~9, Cr3+ chemically reacts to form a precipitate, such as chromium hydroxide (Cr(OH)3). But this method unfortunately produces excess chromium-contaminated sludge, which requires additional techniques to treat and remove, and will only bring additional costs. Chemical precipitation is the technique that is slightly more developed, easier to operate, and cheaper in its initial investment, and tends to be the more common method used nowadays.

Regarding the initial investments in these treatments, for a 50~200 ton wastewater treatment daily, enterprises will need to purchase machinery, such as a reaction pool, precipitation pool, and filtration systems, which will cost around 400 thousand to 1.2 million RMB, with an average of 800 thousand. The architectural and construction costs might be around 600 thousand, with specific designs and electronic devices around 200 thousand, for a total of around 1.8 million RMB. Most of these companies desire automatic systems with a central control system monitored by workers, but a majority of these systems should be completely automatic to be attractive to companies.

Policy Details and Secondary Industries

The environmental policies nowadays are getting stricter, and the importance and demand of wastewater treatment methods have only accelerated. If Cr6+ and other wastes get contaminated in groundwater or soils, the entire ecosystem in the area will be harmed, causing drastic consequences to local inhabitants. Larger enterprises, such as Huawei and Apple, are repeatedly pressured to adopt environmentally friendly mechanisms and wastewater treatment methods. Huawei, for instance, has the Environmental, Social, and Governance (ESG) framework, which pays special notice to ensuring that all of Huawei’s industrial processes meet local governmental standards and remain as sustainable as possible.

Current enterprises also desire wastewater treatment processes that possess a balance in both efficiency and price—something that can remain efficient in the long term, has low costs, and has the ability to reuse materials or remain sustainable in the treatment processes.

Additionally, apart from known industries such as stainless-steel electroplating, fuel, leather factories, and chemical industries, we learned that the semiconductor industry—particularly with chips—will have a demand for wastewater treatment systems, as their engineering processes require high-quality, clean water. Chromium has the potential to contaminate their water sources through chromium plating, which can enhance electronic components’ corrosion resistance. Similarly, the vehicle manufacturing industry and the aerospace rocket industry use chromium plating for decorative and functional purposes, such as coating the surfaces of these devices and ensuring that they don’t corrode.

Investment and Product Improvements

We then asked the expert about some factors that he was most attracted to when considering investments. To him, the most important aspect is the technology’s core competitive advantages, including its level of development and commerciality. Then, he considers the market, including the possible size and projected growth of the market, the demand and supply chains for the product, and whether or not the product is sold between businesses or to consumers. In terms of the invested company, he recognizes the valuable qualities of teamwork, knowledge, ability, and the structure of their business model. Mr. Zhang noted that the current size of the wastewater treatment market, specifically for Cr6+, is around 10 billion USD, demonstrating a highly valuable and competitive future market for our business.

Lastly, we inquired about business models and other features of companies that left a great impact or possessed distinct qualities that made them stand out from other businesses. Expert Zhang introduced a firm known as Evoqua, a wastewater treatment company based in Pennsylvania, US. Not only did this firm provide wastewater treatment technologies, but they also created detailed plans and long-term, after-sales services, providing engineers and consultants who can give advice or solutions to their customers. This allows the customer and the firm to initiate long-term, highly interdependent dialogues that bring the customer and firm closer together, forming close relationships that encourage the customer to purchase more of the firm’s products and recognize or advertise the firm’s professionalism, attracting more customers in the future.

Stakeholder suggestions

Expert Zhang noted that our product will have to make improvements or amends to lower its input costs, especially when dealing with methods to decrease toxic sludge, or to limit the volume of chemical agents used, and most importantly, ensuring that the costs of electricity and energy are greatly decreased. Furthermore, our hardware machine will be able to stand out if it contains the feature of reusability, where materials in the toxic sludge or wastewater could be filtered out and reused for another purpose, creating value from waste, which can mitigate the costs of our product.

Suggestion & inspirations Implementation

In our future plan, we will pay more attention to researching and developing the pollutant reusage features, variable cost decreasing features, and efficiency maximizing technologies. We will also make sure to set the price of our Microbial Remediator (for specifics, go see the business plan) lower than the market price, Mr. Zhang stated to increase our competitiveness in the market.

Figure 16

Introduction

The iGEM Team Crouton visited the WEIPU Testing Technology Company in Shanghai, aiming to broaden our understanding of the inspection and testing industry, particularly in terms of heavy metal detection, and received future insights on reducing toxic metals and other contaminants.

Upon arrival, we were first introduced to Dr. Xiao, the Sales Director of WEIPU Testing Technology, who showed us the various technologies that specialize in food inspection and determine whether or not food specimens possessed certain levels of heavy metal, micro-plastics, or other chemical contaminants that may be higher than China’s food safety standards, and pose significant risks to the public’s health and safety. Dr. Xiao showed us through the Organic Detection Labs, Inorganic Detection Labs—where most of the metal detection takes place, as well as the detection of volatile components, high-boiling point substances. Dr. Xiao then introduced us to Dr. Zhu, the Technical Supervisor of WEIPU Testing Technology, who specializes specifically in heavy metal detection. Dr. Zhu took us on a tour through technologies such as Liquid Chromatography and Mass Spectrometry, both of which help determine the precise molecular identification of possible contaminants, including heavy metals. iGEM Team Crouton members learned a significant amount of new knowledge related to the detection of heavy metals that were not Chromium—including Arsenic, Mercury, Graphite, Lead, and much more—broadening our spectrum and our understanding of related inspection fields.

Q&A section

After both experts and iGEM Team Crouton members gained a substantial understanding of each other’s goals and professions, we began discussing ways that our project—both its research and business aspects—could be improved in the future, introducing another professor, Dr. Chen, who specialized in environmental detection. We asked questions including:

1. If we were to install our Cr6+ wastewater detection and degradation product in large, automated factories, what sizes would be suitable for our machinery?

- It really depends on the amount of wastewater that our customer is releasing—the  concentration of contaminated substances (say, heavy metals) and the volume of wastewater, as well as the budget our customers are willing to provide. In addition, we must also consider the existing international and national standards for this kind of technology, and also understand that we must include room for the degradation and detection bacteria, as well as methods for these bacteria to survive inside our hardware machinery.

2. What sort of international/national standards or laws (like GB or ISO) must our product meet?

- They recommended taking a look at the GB/T 5750, GB/T 1576, and GB/T 8538-2008, which primarily focus on the requirements necessary for meeting drinking water standards in China. There’s also China Metrology Certification, or the CMA Certification, which will be necessary for ensuring that our customers possess enough trust in us.

3. What sort of standards or requirements in our products will most appeal to customers?

- This depends on the customers’ roles themselves. Some research organizations or universities, particularly ones connected to the government, might not have strict requirements on the amount or concentration of Cr6+ that must be degraded, as their Cr6+ emissions are rather limited in comparison to industrial companies and organizations, who will have a high demand for Cr6+ degradation. We must truly understand who our customers are like and what their priorities are, in order to attract substantial numbers of customers.

4. In the realm of WEIPU Testing Technology’s customer network, which industries or locations do you recommend we connect with to serve as our company’s initial testing area?

- They recommend Shanghai, as that is where a lot of their company is, and in areas such as Songjiang or Songshan, factories—especially chemical engineering factories—are highly prevalent. They think that our product might not be the most suitable for brands that don't produce as much Cr6+, as we must recognize customers that truly have the demands that our product provides.

5. How does WEIPU Testing Technology consider collaborative partners and other companies that you may be willing to work together with and will you be interested in working with heavy metal treatment companies?

- They do not have many collaborative partners, but they do work with a company named Kangma-Healthcode; said company conducts inspections and detections, but for a wider variety of substances. While their collaborative partners are only concentrated on a few for now, they are still open to more opportunities in the future.

Other details they asked on our product:

- Your product must be adequately tested. The only way you’ll be able to persuade customers to purchase your product would be if you present enough data to prove that your product is able to reduce the presence of Cr6+ by a significant amount, including its rate of degradation, efficiency, and survivability under specific conditions.

- Cost, as customers have a limited budget and will demand products that can perform the testing and degrading of multiple different heavy metals and contaminants, not just Cr6+ singularly. Furthermore, considering the difficulty in maintaining the survivability of bacteria, you must ensure that your product has a limited cost that is not significantly above the prices of other substitutes in the industry.

- You must understand and maybe customize the shape and size of your product depending on your customer (concentration + volume + amount of Cr6+ released) before you create or advertise your product.

Reflection

Through this visit to WEIPU Testing Technology Company, iGEM Team Crouton members received valuable new information about different ways to improve the quality and efficiency of our product. During our interviews and conversations with one another, iGEM Team Crouton members learned that we must continuously and adequately test our product to ensure that it manages to detect and degrade Cr(VI) every single time. WEIPU experts like Dr. Zhu and Dr. Chen emphasized that only through repeated, verified testing can we truly prove that our product works as it should, and thus be able to attract customers, detailing that the rate of degradation, efficiency, and the survivability of bacteria under these specific conditions must be monitored and recorded.

Furthermore, our interviewees also focused greatly on the costs of our product, emphasizing that our customers have a limited budget. With that, they gave us the suggestion to make our product more practical for industrial use. As we initially introduced them that our Microbial Remediator (for specifics, go see buisness plan), can only degreade Hexavalent Chromium, we adapted to their suggestions by redesigning our machine into being able to degrade all microbe-degradable pollutants.

Conclusion & Implementation

Through our comprehensive Integrated Human Practices, our project has evolved from a initial concept into a robust and responsibly-designed solution. Engaging with a diverse range of stakeholders—including the public, scientists, medical professionals, industry experts, and government regulators—provided us with invaluable, multi-faceted feedback. This iterative dialogue directly shaped our project's direction, leading to critical improvements in biosafety (e.g., UV sterilization), efficacy (e.g., complete Cr(III) precipitation and filtration), and real-world applicability (e.g., focusing on industrial wastewater streams). These interactions ensured that our solution is not only scientifically sound but also socially responsible, addressing genuine market needs and safety concerns. Our journey exemplifies how synthetic biology can be effectively guided by continuous community and expert engagement to create a meaningful impact on environmental challenges.

Our project is designed for real-world application with a clear implementation strategy focused on industrial wastewater treatment. We envision our solution being adopted and used in the following ways:

1. Proposed End Users

Our primary end users are industrial enterprises that generate hexavalent chromium (Cr(VI)) as a byproduct of their manufacturing processes. This specifically includes:

• Electroplating and Metal Finishing Companies: For corrosion resistance and decorative coatings.
• Leather Tanning Industries: Which use chromium salts to stabilize leather.
• Textile Dyeing/Printing Industries: That utilize chromium-based dyes.
• Other Industries: Such as chromite processing and power plants, where chromium contamination is a potential risk.

These enterprises face regulatory pressure and potential fines for discharging non-compliant wastewater. Our system provides them with a cost-effective, on-site solution to pre-treat their wastewater, ensuring it meets national standards (like China's GB18918-2002) before it is sent to municipal treatment plants or discharged.

2. Envisioned Usage

We envision our Premium-Level Microbial Remediator being integrated directly into our clients' existing wastewater management infrastructure. Its fully automated, sensor-driven operation allows for continuous treatment with minimal manual intervention. The key to adoption is high flexibility and customization:

• Modular Design: Customers can purchase the complete system or customize it based on their existing facilities (e.g., using their own water tanks to reduce cost).
• Scalable Solutions: For smaller-scale or specific needs, customers can purchase our standalone E. coli Pack for manual detection and degradation of Cr(VI), though this requires more labor.
• Multi-Pollutant Treatment: The bacterial container is designed not only for our specialized Cr(VI)-degrading E. coli but can also accommodate other engineered bacteria to target a wider range of contaminants like heavy metals, dyes, and nitrogen compounds, making it a versatile platform.

3. Real-World Implementation Plan

Our strategy for implementing the project involves a phased approach:

• Phase 1: Pilot Testing and Certification. We will collaborate with early-adopter industrial partners in areas like Shanghai's Songjiang district, as suggested by WEIPU experts, to conduct rigorous on-site testing. This phase is critical for gathering performance data under real conditions and obtaining necessary certifications (e.g., China Metrology Certification - CMA).
• Phase 2: Market Entry and B2B Sales. Initially, we will focus on direct Business-to-Business (B2B) sales of our Microbial Remediator units and E. coli Packs to the identified industrial end-users. We will emphasize our product's cost-efficiency, automation, and compliance capabilities.
• Phase 3: Strategic Expansion and Service Integration. Following the advice of investor Mr. Zhang, we will evolve from a product seller to a solution provider. This includes offering long-term maintenance, consulting services, and customized treatment plans, building lasting relationships with our clients, similar to the successful model of companies like Evoqua. Future collaboration with governmental bodies as contractors for regional pollution control is also a long-term goal.

By focusing on industrial needs, ensuring flexibility, and pursuing a clear, staged rollout, we are confident in the successful implementation of our project to address the critical challenge of hexavalent chromium pollution.