| Ulink-SZ - iGEM 2024

Overview

As one of the world's largest shrimp and crab producers, China produces a huge amount of shrimp and crab shell waste every year, according to relevant reports and studies, about 5.65 million tons of shrimp and crab shell waste is generated in 2023. However, how difficult is it to recycle discarded shrimp and crab shells? What is the attitude of public and related companies? Does the government support the development of this project in the future? In the face of these problems, we have carried out a series of explorations.

Highlights

Through a survey of the public, we found that although people do not have a good understanding of the recycling value of shrimp and crab shells, most people are willing to participate in sorting and recycling. In addition, the public is open to the use of chito-oligosaccharide in medical and daily chemical products, but acceptance is affected by the source and quality of the product.
In the catering and aquaculture industries, enterprises generally do not implement separate separation and recycling of shrimp and crab shells, but they are supportive of the recycling mechanism that the government may launch. Experts suggest that recycling rates and public participation can be increased through intelligent recycling systems and incentives.
Through our engagement with Professor Deng, we gained critical expertise that directly influenced our project design. By incorporating enzymatic methods for chitin extraction and focusing on the production of high-purity, application-specific chitooligosaccharides, we optimized our process for efficiency and commercial viability.
At the government level, the vice president of the Guangdong Cleaner Production Association proposed that the government supports enterprises to recycle waste and encourage technological innovation. At the same time, the need to consider public acceptance and education costs when promoting chito-oligosaccharide products was emphasized.

In summary, the recycling of shrimp and crab shells has great potential in China, but it requires the joint efforts of the government, enterprises and the public, as well as technological innovation and policy support to achieve effective resource recovery and sustainable environmental development.

1. The Current Situation of Shrimp & Crab Shells in China

China is one of the world's largest producers of shrimp and crabs, and the amount of shrimp and crab shell waste generated each year is staggering. According to the 2023 National Fishery Economic Statistical Bulletin, China's crustaceans (shrimp and crab) products from aquaculture and marine have reached 9.4189 million tons in 2023. These wastes mainly come from aquatic product processing, agricultural breeding, seafood consumption and other channels, and it is speculated that aquatic product processing and seafood consumption are the main channels for producing shrimp and crab shells.

In the face of this situation, various regions in China have introduced a series of solid waste management and resource recovery policies according to the actual situation, especially in the coastal areas, which benefit from the intensive activities of aquaculture and fishery, the waste recycling and treatment facilities are relatively complete, and the recycling rate is relatively high, accounting for about 20% to 30%.

In shrimp and crab shells, chitin is abundant, can be used to produce a variety of chemicals and materials. If the proportion of shrimp shell and chitin is 60% and 25% respectively, then the amount of chitin abandoned in China's shrimp and crab products in 2023 will be as high as 1.41 million tons. However, most of these shells are disposed of in landfills or incineration, which not only causes serious pollution to the environment, but also a huge waste of resources.

2. Possibility of Recycling

2.1 Consumers and Restaurants Investigation

In China, garbage sorting has become a deeply rooted policy and daily habit. Under this system, discarded shrimp and crab shells are usually classified as food waste. However, we speculate that there is still a lack of awareness of the fact that these seemingly useless wastes actually contain recyclable value. In order to test this hypothesis, we conducted questionnaires and interviews to get a deep understanding of the public's real thoughts. In addition, we are also concerned about the public's acceptance and perception of converting these shrimp and crab shells into chito-oligosaccharides and applying them to daily chemical products and the pharmaceutical industry.

Public Survey

In a survey of consumers, we conducted an in-depth look at the public's perception, attitudes and acceptance of shrimp and crab shell recycling. The findings reveal several key points:

1. Disposal status of shrimp and crab shells:The vast majority of respondents (72.7%) discard shrimp and crab shells as kitchen waste, which reflects the lack of public awareness of the potential value of shrimp and crab shells. However, it is worth noting that a significant proportion of respondents (14.9%) are already aware of the recyclability of shrimp and crab shells, which indicates that the public is increasingly aware of environmental protection and the gradual recognition of the value of resource recycling.

2. Recycling attitude: The public has a positive attitude towards the recycling of shrimp and crab shells, with 86.6% of the respondents expressing their willingness to separate shrimp and crab shells for recycling during garbage sorting. This high percentage of positive responses shows the public's support and willingness to participate in improving the recycling rate.

3. Product acceptance:Although the respondents did not have a high level of understanding of the products made from the recycling of shrimp and crab shells (40.45% of the respondents said that they did not know the application status of chitin and chito-oligosaccharides), in terms of acceptance, 55.56% of the respondents said they were willing to accept and use these products. This shows that although the level of knowledge needs to be improved, the public has an open and positive attitude towards new environmentally friendly products.We still note that about 17% of respondents are not very receptive or unacceptable to use these products, which is enough to raise concerns during the product development process.

Field Research of Lobster Restaurants

In the field research of lobster restaurants, we gained an in-depth understanding of the current situation and attitudes of shrimp and crab shell recycling in the catering industry. The survey results show that at present, catering enterprises generally mix shrimp and crab shells with kitchen waste, and do not implement separate classification. This practice reflects that the industry's understanding of shrimp and crab shell recycling is still in its infancy. In response to our inquiries, caterers generally said that they were not aware of the recyclability of shrimp and crab shells. When it comes to the possibility of a dedicated recycling mechanism by local governments, they have expressed their willingness to support it without affecting their daily operations and economic benefits, but they still have reservations about the feasibility and reliability of this new model.

Combined with the analysis of previous questionnaires conducted with consumers, we can find that although the public has insufficient awareness of the recycling value of shrimp and crab shells, they are willing to separate and recycle them. This shows that although the fine classification and recycling of food waste has not yet been popularized in public awareness, through education and policy guidance, both the public and the catering industry may become an important force to promote the development of the recycling system.

We can also see that it is not only difficult to establish a mature and complete recycling system, but also a long way to go in terms of public education and guidance.

2.2 Enterprises Interview

In order to understand the treatment of waste shrimp and crab shells by aquaculture industry,we conducted in-depth interviews with two hairy crab farming companies in Suzhou and consulted Professor Deng from Wuhan University, who specializes in chitin research.

Hairy Crab Farming Enterprise

The two aquaculture companies specialize in the breeding and sales of hairy crabs, and it is understood that they have not yet implemented a recycling program for crab shells. According to Mr.Gu, unqualified crabs generally sink directly into the lake after being shelled, which is the easiest and lowest cost. Qualified crabs end up in the consumer market, which is a challenge due to the dispersion of points of sale.

As for how to improve the enthusiasm of household consumers for crab shell recycling, Mr. Fu put forward innovative insights. He suggested that incentives could be used to incentivize consumer participation, such as carbon credits by disposing of shrimp and crab shell waste separately, which would not only increase recycling rates, but also increase consumers' awareness and sense of participation. This incentive-oriented approach may be an effective way to promote shrimp and crab shell recycling.

Professor Hongbing Deng, Wuhan University

Professor Tang also emphasised the importance of shrimp and crab shell recycling, which he pointed out is a topic that is getting more and more attention. Conventional disposal methods not only burden the environment, but also fail to fully exploit the resource potential of these wastes. Therefore, a series of innovative technologies and methods are being actively explored, among which the extraction and application of chitosan is a typical example. This substance not only has a wide range of application prospects, but also can effectively enhance the utilization value of shrimp and crab shells.

When discussing the recycling mechanism, Professor Deng put forward forward-looking suggestions for building a smart recycling system. He suggested using intelligent equipment combined with blockchain technology to create a transparent and efficient shrimp and crab shell recycling tracking system. Such a system ensures traceability of the recycling process and increases data transparency, thereby motivating businesses and consumers to participate more actively in recycling. Through intelligence and technological innovation, it can open up a new path for the recycling of shrimp and crab shells, and promote the development of this field in a more sustainable direction.

2.3 Government Manager Interview

Peng Chen, Vice President of Guangdong Cleaner Production Association

China attaches great importance to waste sorting, and various regions are implementing localized sorting and recycling policies. China also attaches great importance to green and low-carbon and waste recycling. In order to understand the government's attitude towards the classification and treatment of food waste, we contacted the vice president of the Guangdong Cleaner Production Association and obtained the following information:

President Chen told us that there are generally three types of waste that the association and the government are concerned about: industrial sources, agricultural sources and social sources, among which the waste from social sources is varied, covers a wide range of areas, and is very complex to deal with, so now the government is strongly supporting enterprises to recycle waste, especially encouraging them to develop new technologies.

As a government worker, President Chen is very concerned about the impact of the project on the people. First, he pointed out that while chito-oligosaccharides are of great value in the medical and food sectors, the public may have reservations about products that use food and beverage waste as raw materials. Therefore, the promotion of such products needs to take into account the level of public acceptance and may require significant investment in publicity and education. Secondly, he stressed that the feelings and participation of residents must be fully considered when dealing with social waste that is closely related to residents' lives, which means that when promoting shrimp and crab shell recycling projects, public participation and education programs need to be designed in a targeted manner.

Overall, Mr. Chen's attitude shows that while the government is open to such projects, the success of the project depends not only on technical feasibility, but also on a combination of factors such as economic cost, public acceptance, and resident participation.

3. Government Policy Support

From the perspective of policy development, the management and utilization of food waste in China have been continuously strengthened and improved. In particular, the 2024 policy document mentions the need to promote the level of waste recycling and reuse. As a part of food waste, the recycling and utilization of shrimp and crab shells are in line with the above policy trends. In addition, they are rich in useful chemicals such as protein, calcium carbonate and chitin, and have high resource utilization value, and are expected to become key wastes in the near future.

In terms of policy support, the state encourages the development of the resource recycling industry, and provides tax incentives, financial support and technical support and other measures. This provides a good policy environment and market opportunities for the recycling of shrimp and crab shells.

4. Production and Application of Chitooligosaccharides

Regarding the use of shrimp and crab shells to produce high value-added waste, we consulted Professor Deng, an expert in chitin modification and conversion. His expertise provided important insights and had a significant impact on our project design.

Main Gains and Impact on Project Design:

1. Necessary trend of green production of chitosan

Expert advice: Professor Deng suggested using green and environmentally friendly technology to extract chitin, such as the enzymatic method. Specifically, he recommended a one-step fermentation process using formic acid combined with acid-resistant protease, which can achieve more than 99% demineralization and more than 95% deproteinization.
Project implementation: Chitin is the most important substrate of our project. Professor Deng's advice helped us to clarify the important ideas and methods of substrate treatment. We will also use this method as our preferred option for future research to reduce costs and minimize the impact on the environment.

2. Enzyme Selection and Optimization:

Expert Advice: He emphasized the importance of selecting appropriate enzymes like chitosanase for degrading chitin and optimizing reaction conditions (pH, temperature, enzyme concentration) to improve COS yield and purity. He also highlighted the need for thorough enzyme screening due to the sensitivity of enzyme activity to reaction conditions.
Project Implementation: Guided by his suggestions, we chose CDA and CsnB enzymes for COS production. We performed site-directed mutagenesis on CsnB to enhance its activity. By leveraging the synergistic effect of both enzymes, we aimed to increase the yield and purity of chitobiose, a specific COS.

3. Promoting Environmental Sustainability and Economic Incentives:

Expert Insight: Professor Deng noted that utilizing shrimp and crab shells—abundant and low-cost waste from food processing and catering—as raw materials presents an environmentally friendly solution to waste disposal challenges.
Project Implementation: By demonstrating a profitable use for these waste materials through the production of valuable COS, our project supports environmental sustainability and provides economic incentives for enterprises and governments to invest in waste recycling initiatives.

Focusing on High-Purity, Specific Degree of Polymerization Products

Inspired by Professor Deng, we conducted further research on the purity and commercial value of chitosan oligosaccharides.

the purity of chitosan oligosaccharide in the pharmaceutical field is more than 95%, the food industry and cosmetics are required to be more than 90%, and the agricultural requirements will be lower. And different applications may require chito-oligosaccharides with a specific degree of polymerization. For example, chito-oligosaccharides with a high degree of polymerization may be more suitable as an integral part of a drug delivery system, while chito-oligosaccharides with a low degree of polymerization may be more suitable as food additives. High-purity, specific degrees of polymerization, chito-oligosaccharides can better meet the needs of these specific applications. Therefore, the development of chito-oligosaccharides with more commercial value will further promote the process of shrimp and crab shell waste recycling at another level, and also promote the willingness of enterprises and governments to invest in this work.

Table: The Price of Pure Chitosan Chitooligosaccharides

Chitooligosaccharides	Content (mg)	Price (CNY)
(GlcN)2	10	518
(GlcN)3	10	585
(GlcN)4	10	650
(GlcN)5	10	1235
(GlcN)6	10	1560

Based on the above information, we focused our research on the production of high-purity, single-polymerization chitosan oligosaccharides. The key to producing chito-oligosaccharides is CsnB, so we focused our research on the modification of CsnB. At the same time, in order to simplify the process and improve production efficiency, we set up experiments to optimize cultural conditions and enzyme activity.

5. Recycling and Product Application Assumptions

Based on the above investigation, we have some thoughts on the establishment and application direction of the recycling system.

5.1 Recycling Assumptions

For Aquatic Products Processing Enterprises:

Cooperative mechanism: Establish a direct cooperative relationship with aquatic product processing enterprises to encourage them to separate and recycle shrimp and crab shells in their production process by providing technical and financial support.
Centralized treatment facilities: Centralized shrimp and crab shell recovery and treatment facilities are set up near the aquatic product processing area to facilitate efficient collection and treatment.
Policy incentives: Use government support and incentives, such as tax breaks, subsidies, etc., to reduce the cost of companies participating in recycling.

For Individuals, Communities:

Community Recycling Programme: Promote the shrimp and crab shell recycling programme within the community by setting up dedicated recycling containers and regular recycling services to facilitate residents' participation.
Education and Awareness Campaigns: Conduct education and awareness campaigns to raise awareness among residents about the value of shrimp and crab shell recycling and encourage them to participate in recycling activities.
Reward system: Implement a reward system, such as points, coupons or small gifts, to encourage residents to participate in the sorting and recycling of shrimp and crab shells.

5.2 Product Application Assumptions

For the chito-oligosaccharide products produced by raw materials from different recycling methods and channels, at the application level, we envision that it is necessary to distinguish them in the early stage of product promotion to ensure the quality and suitability of the product. When the public gradually recognizes the concept of circular economy and green development, it promotes the application of products in various fields.

The initial product application direction is mainly divided into:

The shrimp and crab shell waste collected by aquatic product processing enterprises may have high quality specifications and are suitable for high value-added products, such as medical supplies, cosmetics, food, etc.;
Home kitchens and restaurants, where quality can vary depending on how they are collected and handled, are suitable for products that are less demanding on raw materials, such as plant growth promoters, environmentally friendly materials, feed additives, etc. in the agricultural sector.

5.3 Public Education and Outreach Programmes

To ensure the success of the project, we will design a series of public education activities to raise public awareness of the circular economy and focus on addressing public concerns about the origin of chito-oligosaccharide products. Through online and offline promotions, as well as collaboration with schools and communities, we hope to increase public acceptance of green products and promote the concept of sustainable development in society.

We conducted a public promotion in two communities in Pukou District, Nanjing, introducing innovative projects to the elderly and children in the communities. Recycling staff in some communities in Suzhou presented us with elaborate brochures to show them how trash can be turned into high-value products. Convey the concepts of waste recycling, green products, and sustainable development to them. [Click for details]

As we see public interest and support for innovative projects in these outreaches, we believe that community events should continue to be done on a regular basis. We plan to use the winter and summer vacations to carry out more promotional activities in the surrounding communities. When designing promotional activities, more attention will be paid to interaction with residents.

In the school, we had a discussion with the MUN community organization in the school, which has been established in the school for a long time and has a certain mass base. The members of the community are very supportive of our project and believe that it is very sustainable. Therefore, they expressed their willingness to work together again in the future. We discussed finding the right opportunity to co-curate an exhibition on "Green Products" to promote more people to understand waste recycling and the circular economy. [Click for details]

6. Summary

Every year, not only in China, but also in the world, seafood consumption will inevitably produce a large amount of waste, especially shrimp and crab shells. These wastes are rich in chitin and have great potential to be converted into high-value products such as chito-oligosaccharides.

Although there is currently a lack of awareness among the public and companies about the recycling value of shrimp and crab shells, surveys show that people are willing to participate in waste sorting and recycling, and the catering and aquaculture industries are also supportive of possible government recycling mechanisms. The intelligent recycling system and incentive mechanism proposed by relevant professionals provide new ideas for improving the recycling rate and public participation. The government's support for enterprises to recycle waste and encourage technological innovation have created a good policy environment for the recycling of shrimp and crab shells.

With the continuous progress of chitin extraction technology, the production efficiency and application range will be significantly improved. In many fields such as food, medicine, and agriculture, chito-oligosaccharide has broad application prospects, which will help promote the green development of related industries. On the whole, the recycling of shrimp and crab shells can not only reduce environmental pollution, but also promote the efficient use of resources, which is in line with China's current policy trend of waste recycling and reuse.

In the future, through the joint efforts of the government, enterprises and the public, as well as driven by technological innovation and policy support, shrimp and crab shell recycling is expected to play a more important role in China's circular economy and sustainable development, bringing positive impacts to society, environment and economy.

References

[1] National Development and Reform Commission report on urban domestic waste classification and treatment facilities

[2] "14th Five-Year Plan" for the development of urban domestic waste classification and treatment facilities

[3] Opinions of the General Office of the State Council on Accelerating the Construction of a Waste Recycling System, Energy Conservation and Comprehensive Utilization of Resources, Chinese Government Network

[4] People's Republic of China Law on the Prevention and Control of Environmental Pollution by Solid Waste, Laws and Regulations, Chinese government website

[5] China Association of Circular Economy

[6] Opinions of the General Office of the State Council on Strengthening the Remediation of Gutter Oil and the Management of Kitchen Waste

[7] 2023 National Fishery Economic Statistical Bulletin

[8] Shaoru WANG, Yungang LUO. Research progress in biological function of chitooligosaccharide and its application in biomedical field [J]. Journal of Jilin University (Medicine Edition), 2024, 50(4): 1164-1172.

[9] ZHENG J, YUAN X, CHENG G, et al. Chitosan oligosaccharides improve the disturbance in glucose metabolism and reverse the dysbiosis of gut microbiota in diabetic mice [J]. Carbohydrate Polymers, 2018, 190: 77-86.

[10] Zhiyan Consulting company

[11] China Research Institute of Puhua Industry, 2024-2029 China chito-oligosaccharide industry in-depth research and investment opportunity analysis report