. Implementation .

Overview

The current climate crisis urgently demands effective solutions. Forests play a crucial role in carbon sequestration, reducing the greenhouse effect, and mitigating climate change. However, a significant amount of timber is used for paper production. Improving the efficiency of paper recycling and deinking can help protect forests and alleviate environmental and climate challenges.

Traditional deinking methods face issues of inefficiency and environmental pollution. Our innovative approach (see design for details) enhances deinking efficiency and reduces pollution, thereby increasing the recycling rate of paper. This also promotes the green transformation of related industries, providing a new pathway to address the climate crisis.

Proposed Implementation

1.Target Users

1.1 Recycled Paper Mills

Our project primarily targets recycled paper mills that use waste paper as raw material. In the context of severe climate challenges and scarce forest resources, the utilization rate of waste paper remains suboptimal, and the deinking process often produces pollutants like "black liquor" (see HP for more details). By implementing our optimized deinking and pulping system, we aim to enhance deinking efficiency, increase paper recycling rates, reduce environmental pollution from traditional deinking methods, and promote the sustainable development of the paper industry and its related supply chains.

1.2 Relevant Research Teams

In our laboratory, we have simulated and optimized industrial deinking processes, developing a comprehensive experimental protocol (see protocol for more details). This provides valuable references and methods for other research teams, fostering further innovative research. Notably, we conducted systematic tests on the functionality of signal peptides (see software for more details), assisting other teams in selecting appropriate signal peptides as needed, thereby supporting the advancement of additional innovative studies.

2. Usage

We use engineered E. coli BL21 to release or secrete enzymes such as cellulase, monooxygenase, and laccase to treat paper. These enzymes effectively separate ink from paper fibers, achieving a biphasic separation of pulp and ink. Enzymatic treatment enhances the separation, ensuring thorough division of ink and paper fibers.

In the subsequent process, limonene is used to extract and separate ink from the fibers, improving efficiency and reducing fiber loss. As a biosynthesized terpene, limonene effectively enhances ink separation, making the paper recycling process eco-friendlier and more efficient.

Additionally, to address heavy metals in the wastewater from the deinking process, we designed a heavy metal ion adsorption system. Engineered E. coli BL21 is cultured in a fermenter to utilize their adsorption capacity to capture heavy metals from the wastewater. The process involves introducing wastewater into the fermenter, where the cultured strains treat it over time. After treatment, the bacterial sediment at the bottom of the fermenter, containing adsorbed heavy metals, is collected.

Safety

1.Bacterial Lysis Mechanism

We designed a lysis mechanism responsive to arabinose, causing bacteria to automatically lyse upon detecting the arabinose signal. This process not only releases enzymes into the environment to perform their functions but also ensures that bacteria do not remain in the environment. Through this mechanism, bacteria naturally decompose after completing their tasks, preventing biosafety issues.

2.Suicide Switch

Additionally, we developed a blue light-activated suicide switch. When exposed to blue light, this switch is activated, triggering bacterial lysis and death. We treat the effluent with blue light to ensure complete elimination of bacteria. This measure further ensures environmental safety by preventing uncontrolled bacterial spread.

3.Risk Assessment

Since engineered bacteria are used when the project is implemented, there are potential risks to public health and the environment. Therefore, before we put our devices into production, testing, and applications outside the laboratory, extensive testing should be performed to ensure that our engineered bacteria are safe for humans and the environment.

Besides, China passed a new biosecurity law and it come into effect on April 15, 2021. The law establishes systems for biosecurity risk prevention and control, including risk monitoring and early warning, risk investigation and assessment, and information sharing. It also has provisions to prevent and respond to specific biosecurity risks, including major emerging infectious diseases, epidemics, and sudden outbreaks, and biotechnology research, development, and application. To keep our activities legal, applying for permits and approvals is necessary if we execute our proposed implementation.

Challenges

Currently, we have made some progress in ink removal from everyday materials and proposed various methods and suggestions. However, achieving the ideal ink removal effect is still a work in progress. We plan to explore new technologies to reduce waste paper in daily life and promote sustainable development.

In research and development, our project is dedicated to exploring more efficient enzymes to improve deinking efficiency. This will help enhance the quality of recycled paper and further advance the recycled paper industry, promoting green and sustainable development.

Finally, we aim to collaborate with recycled paper mills for on-site experimental testing. This will help assess the practical feasibility of our current project design and microbial strains, identify and address any shortcomings, and lay the experimental foundation for the project's eventual industrialization.