Project Context
Driven by the growth of the new energy vehicle industry, global demand for lithium batteries has increased rapidly. According to the "2024 China Lithium-Ion Battery Industry Development White Paper," jointly published by EVTank and the EVI Economic Research Institute, total global shipments of lithium-ion batteries reached 1202.6 GWh in 2023, marking a year-on-year growth of 25.6%. In the foreseeable future, the available stock of key metal minerals needed for lithium battery production is unlikely to meet the rising demand for mineral resources. Furthermore, used lithium batteries contain heavy metal ions and organic pollutants, posing significant environmental risks.
Recycling lithium-ion batteries not only addresses the shortage of essential metal resources and prevents pollution from heavy metal ions in waste batteries but also reduces carbon emissions by over 50% during the production of lithium batteries. In the industrial sector, the predominant recycling technologies for lithium-ion batteries primarily rely on extraction metallurgical processes, which are categorized into pyrometallurgy and hydrometallurgy.
Pyrometallurgy does not require pretreatment steps, directly converting waste lithium-ion batteries (LIB) into transition metal elements and lithium-rich slag at high temperatures exceeding 1000°C. However, this method entails substantial energy consumption, high carbon emissions, and low recovery efficiency. In contrast, hydrometallurgy is a more intricate and refined process. It begins with discharging, sorting, dismantling, and preliminary heating of waste LIB to obtain a metal-rich "black powder." This black powder is then subjected to leaching with strong inorganic acids to extract metal elements. Ultimately, metal salts are obtained from the purified leachate. The advantages of hydrometallurgy include lower emissions, milder reaction conditions, and higher metal recovery rates. However, this process consumes significant quantities of chemical reagents, and if the generated acidic wastewater is not properly treated, it can lead to severe water pollution. Additionally, the extraction and separation of inorganic ions are relatively complex processes that further increase costs.
Project feasibility & Advantages
This year, our biological methods are divided into three parts. We begin with black powder, from which metal ions are extracted through a combined leaching process using organic acids. Next, metal ion adsorption and separation are conducted using specific metal-binding peptides displayed on the surface of Yeast. Finally, microbial-induced mineralization results in the formation of metal carbonate precipitation. This modular, system-integrated biological recycling system enhances overall process efficiency and scalability.
1.In the first step, our biological leaching technology demonstrates the lowest energy consumption, minimal pollution, and the highest leaching rate compared to pyrometallurgy and chemical hydrometallurgy. While traditional biological leaching techniques are often criticized for their slow leaching rates, our combined medium leaching method significantly addresses this limitation, achieving an optimal balance between energy consumption and efficiency. Moreover, the use of organic acids generates fewer by-products, reducing the likelihood of metal ions precipitating with impurities, thereby improving the purity of the recovered metals. This presents a clear advantage over strong acid methods. Additionally, employing a dual-acid system allows for effective leaching across a wider range of pH and temperature conditions, thus mitigating process bottlenecks and reducing energy usage. Unlike existing leaching methods that typically target a single metal, our dual-acid approach efficiently extracts multiple metals (such as lithium, cobalt, nickel, and manganese) simultaneously, making it particularly suitable for complex multi-metal systems, such as used power batteries.
2.The second step involves biological adsorption and separation, which uses fewer chemical reagents than the common inorganic ion extraction methods in hydrometallurgy, generates no toxic wastewater, and theoretically offers higher separation efficiency (due to the chelation effect, the binding energy and specificity of metal-binding peptides with metal ions significantly exceed the solvation energy differences of conventional extractants). To further enhance the effectiveness of adsorption and separation, we have designed a self-assembly approach. During industrial implementation, the utilization of organic acids in the leachate and ammonium ions from mineralization waste can simplify wastewater treatment, reduce cultivation costs, and increase material utilization in bioprocessing.
3.The third step of biological mineralization focuses on regenerating electrode materials after extracting key ions. Metal carbonates have a low decomposition temperature, resulting in lower energy consumption during the preparation of electrode material precursors compared to commonly available manganese sulfate and cobalt sulfate, which are typically produced through other recycling methods. Furthermore, during the heating process, the mineralized by-products can be thermally controlled to induce carbonization, forming structures where nano-sized metal oxide particles are deposited on interconnected micron-sized carbon networks (where filaments from sedimented microorganisms are mostly in contact and interlinked after carbonization). In this structure, carbon acts as a current collector, providing excellent conductivity, while the attached nano-sized metal oxides possess a high specific surface area and exhibit significant electrochemical activity. This material demonstrates exceptional performance as an electrode material.
Target user
We expect our users to consist of three main groups: Lithium Battery recycling companies, Research team for battery recycling, and other iGEM teams who will be interested in bioremediation of heavy metals.
1. Battery Recycling Enterprises
After engaging in discussions with battery recycling enterprises, we have garnered valuable insights. The leaching technology employed in our approach aligns well with the equipment and facilities commonly utilized in domestic battery recycling, particularly those that employ hydrometallurgical processes. This compatibility indicates that existing chemical hydrometallurgical recycling plants, which originally utilize chemical leaching methods, can be upgraded to integrate our innovative solutions. Consequently, we should consider collaborating with battery recycling companies by exploring avenues for technical equity partnerships or by providing technical support and services to foster mutual development and advancement.
2. Focused on Research Centers
The Ouroboros project applies synthetic biology techniques to the recycling of lithium battery metals, providing research centers with new directions and tools for investigation. This project not only demonstrates the potential applications of synthetic biology in the fields of environmental science and materials science but also offers researchers in related domains novel research perspectives and methodologies. For instance, researchers can delve into the mechanisms of biomineralization, exploring more efficient methods for metal ion capture and mineralization, thereby enhancing metal recovery efficiency and resource utilization rates. Furthermore, researchers can leverage the technological platform of this project to develop new biomineralization materials, such as high-performance electrode materials and environmental remediation materials, thus providing new technological support for advancements in relevant fields. Additionally, the collaboration between the Ouroboros project and research centers holds substantial promise and potential.
3. Focused on Other iGEM Teams
The Ouroboros project employs techniques such as bioleaching, biosorption, and biomineralization for the recycling of lithium battery metals, offering other iGEM teams new technical references and insights. For example, other iGEM teams can draw from the microbial surface display techniques utilized in the Ouroboros project to develop engineered strains with specific functionalities; they can also adapt the biomineralization technologies implemented in the project to create new biomineralization materials. Furthermore, the experimental design and data analysis methods employed in the Ouroboros project can serve as models for enhancing experimental efficiency and the reliability of results.
Feasibility analysis/strengths analysis
Analysis of Project Advantages:
We have developed a comprehensive treatment pathway that includes leaching, adsorption, and mineralization using common engineering microorganisms. This approach not only reduces carbon emissions and energy consumption but also aids in solid waste management, thereby minimizing soil and water pollution. The treatment of each ton of waste can mitigate the environmental burden by approximately 3.3 tons of CO2, resulting in significant environmental benefits (for benefit calculations, please refer to human practice). Additionally, the application of bioprocessing technology enhances lithium recovery rates while also enabling the recovery of other valuable metals, such as nickel and cobalt, thus achieving comprehensive resource utilization. Consequently, this technology aligns well with governmental and national requirements for achieving zero carbon emissions and promoting environmentally friendly new industries.
At the broader market level, as societal awareness evolves, an increasing number of individuals recognize the importance of environmental protection and resource conservation. Companies are also progressively emphasizing their performance in Environmental, Social, and Governance (ESG) aspects. Our bioprocessing method for lithium battery treatment directly addresses these societal demands. Such social recognition is crucial for the marketability of our treatment approach. If we can establish an industrial-scale wastewater treatment pathway, this technology will have significant economic and environmental benefits across a vast market.
In summary, our advantages can be articulated as follows:
1.From a technological perspective, our innovative technologies are characterized by low energy consumption and environmentally friendly processes. This not only minimizes the ecological footprint but also significantly enhances operational efficiency. The adoption of these advanced technologies leads to a marked improvement in productivity and resource utilization, aligning with global sustainability goals.
2.From a market standpoint, there is a rising demand for lithium battery recycling, which is indicative of the evolving dynamics within the battery industry. This demand aligns with the optimization needs of the sector, as stakeholders increasingly prioritize sustainable practices and circular economy principles. The growth in this market segment presents significant opportunities for investment and development, catering to both consumer and industrial needs.
3.From a societal benefit perspective, there is a growing public awareness and recognition of environmental protection. This societal shift is further supported by national policies that encourage sustainable practices and innovations in the recycling sector. The government's commitment to promoting environmental sustainability creates a favorable regulatory environment, which bolsters our initiatives and aligns with the broader objectives of social responsibility.
Visions of the Future
As the iGEM 2024 competition concludes this October, we are committed to advancing our project, Ouroboros. We have outlined several key areas to focus on:
1.Experimental Optimization We plan to enhance the existing genetic constructs to improve the survival rate of our engineered microorganisms, facilitating accelerated growth in reactors. Additionally, recognizing the challenges associated with scaling up production, we aim to optimize the design parameters of the reactors to ensure optimal growth conditions for the engineered microorganisms.
2.Public Engagement Through our outreach efforts, we have identified a significant challenge in battery recycling: the collection of used batteries from individual consumers. To effectively address this, we need to increase the number of recycling points and raise public awareness. To educate the public about the dangers of improper battery disposal, we intend to continue operating our WeChat account, Bilibili channel, and other social media platforms, disseminating scientific knowledge to encourage good habits regarding waste disposal. Furthermore, we plan to conduct offline educational activities in communities and primary and secondary schools to engage children and the elderly with relevant information.
3.Collaboration with Enterprises Acknowledging that our current experimental and hardware designs are still lacking, we intend to engage in dialogue with enterprises to enhance our hardware and engineering strains. We hope to leverage these collaborations to facilitate large-scale production, thereby transforming existing physical and chemical recycling methods into more efficient recovery processes.
4.Collaboration with Government We plan to initiate discussions with relevant governmental departments to understand current environmental and resource issues, while also advancing our project towards commercialization.
5.Collaboration with Associations We seek to establish preliminary collaborations with various environmental protection associations in Beijing to promote our project and increase its visibility. Subsequently, we aim to collaborate with environmental associations on a national and even international scale to broaden awareness of the importance of environmental conservation.
6.Knowledge Sharing Our genetic constructs and supporting models are available on our website, and we encourage teams in similar fields to learn from and adapt our work.
Despite the preliminary nature of our project, we aspire to expand the application of our technology beyond battery recycling to include areas such as metal ore recovery and waste metal recycling, thereby further advancing environmental protection initiatives.
Challenges
Experimental Part
Part 1: Challenges in Bioleaching
We face several challenges in the bioleaching component:
1.Enhancing Leaching Efficiency: Despite optimizing the leaching solution and microbial culture medium, different metal ions respond variably to leaching conditions in complex metal mixtures. There is a need to improve the overall leaching rate.
2.Metabolic Burden on Strains: Aspergillus niger must proliferate while simultaneously producing organic acids, and the competition between acid production and metabolite accumulation limits the efficiency of acid production. Balancing its metabolic burden is essential.
3.Recovery and Reuse of Acidic Solutions: The extensive use of organic acids increases both costs and environmental burdens. Research is needed to explore how to recover and reuse waste acids while maintaining leaching efficiency.
4.Genetic Engineering Optimization of Strains: Employ CRISPR technology to reduce non-target metabolic byproducts, thereby enhancing leaching efficiency.
Part 2: Challenges in Bioadsorption
The bioadsorption component also faces several challenges:
1.Insufficient Optimization of Bioadsorption Conditions for Yeast: The experimental results regarding the metal-binding peptide enrichment capabilities of engineered Yeast strains have been suboptimal.
2.Screening and Optimization of Metal Ion-Binding Peptides: Develop a secondary peptide library and employ computational simulations to identify high-affinity binding peptides.
3.Co-expression of Genes: Co-express metal resistance, detoxification genes, and metabolic regulatory enzymes to enhance the tolerance of Yeast to metals.
Part 3: Challenges in S. pasteurii Urease Application
Despite successfully achieving the recombinant expression of S. pasteurii urease in E. coli for metal mineralization, we encounter the following challenges:
1.Enhancing SazCA Enzyme Activity: The carbonate generated during catalysis results in acidic solutions, necessitating optimization of surface display, regulation of expression levels, and construction of a suitable microenvironment.
2.Efficiency of SazCA Application: Design efficient reactors, optimize reaction conditions, and explore synergistic interactions with other enzymes to improve overall efficiency.
3.Sustainability: Reduce production costs, improve resource utilization efficiency, and assess environmental impacts.
Challenges in Hardware
We also face several challenges in the hardware aspect:
1.Large Simulation Files: The size of our simulation files adversely affects computational performance, necessitating a reduction in model complexity to obtain preliminary results.
2.Insufficient Accuracy of Intelligent Sorting System: The accuracy of our intelligent sorting system is below expectations, requiring optimization of model settings and consultation with experts to improve the design of 3D models.
3.Inability to Print Experimental Devices: We were unable to print our designed experimental devices. Plans are in place to utilize 3D printing technology to realize the models and seek expert opinions.
Planned but not done in Social Practice
While we have made progress in our social practice initiatives, there are still gaps:
Activities for Individuals with Disabilities: Due to time constraints, we were unable to conduct activities aimed at individuals with disabilities. We plan to organize specialized educational activities in the future.
Insufficient Attention to Battery Heavy Metal Pollution: We will strengthen our outreach efforts to raise awareness of this issue and enhance public consciousness.
