Intensifying Anaerobic Digestion: Biotechnological Innovations for Enhanced Energy Conversion

Dear Colleagues,

Anaerobic digestion (AD) plays a crucial role in the transition towards a circular bioeconomy by transforming organic waste into valuable bioenergy and biofertilizers. The intensification of AD processes, through advancements in industrial biotechnology such as enzymatic biotransformation, is required in order to maximize resource recovery and minimize our environmental impact. This review synthesizes current research on the following topics:

• AD intensification: Exploring innovative approaches to enhancing biogas production and the quality of the digestate.
• Enzymatic biotransformation: Detailing the application of enzymes to optimize the breakdown of feedstock and improve the efficiency of AD.
• Circular bioeconomy integration: Emphasizing the role of AD in closing nutrient loops and promoting sustainable waste management.
• Environmental implications: Analyzing the contributions of intensified AD to greenhouse gas reduction and pollution control. Critically, intensified AD also offers the potential for significant direct reductions in greenhouse gas emissions by capturing methane and displacing fossil fuel use.

By leveraging industrial biotechnology, we can unlock the full potential of AD, creating sustainable pathways for waste valorization and contributing significantly to a resilient and circular bioeconomy.

Anaerobic digestion (AD) is crucial in our transition towards a circular bioeconomy, transforming diverse organic waste streams into valuable bioenergy and nutrient-rich biofertilizers. However, to truly realize its potential, we must embrace innovative intensification strategies. This Special Issue aims to delve into the multifaceted role of AD in forging a sustainable future, and specifically focuses on the following topics:

• AD Intensification: We seek submissions that explore groundbreaking approaches to enhancing biogas production and the quality of the digestate. This includes, but is not limited to, novel reactor designs, advanced process optimization strategies, the integration of pre-treatment technologies, and the application of cutting-edge materials.
• Enzymatic Biotransformation: We encourage the submission of research that details the pivotal role of enzymes and microorganisms in optimizing feedstock breakdown and improving AD efficiency. Contributions should highlight the identification of key enzymes or microorganisms, the development of robust enzyme cocktails, and the engineering of microorganisms for enhanced enzyme production, ultimately leading to improved substrate valorization.
• Circular Bioeconomy Integration: This Special Issue emphasizes the critical role of AD in closing nutrient loops and fostering sustainable waste management. We are particularly interested in research that showcases AD's potential to drive resource recovery, minimize waste generation, and contribute to the development of integrated biorefinery concepts, thereby promoting a truly circular approach.
• Environmental Implications: We aim to analyze the profound environmental contributions of intensified AD, with a focus on quantifying greenhouse gas reduction, assessing the impact of life cycles, and addressing the challenges associated with scaling up AD technologies. Submissions should also explore strategies that mitigate potential environmental risks and ensure the long-term sustainability of AD systems.
• Techno-economic studies: The special issue will also welcome studies that evaluate the economic viability and technical feasibility of the proposed strategies, therefore providing a holistic approach.
• Case studies: Real-world case studies will be of great value to showcase the current state of the art, and the potential for future development.

By leveraging the transformative power of industrial biotechnology and rigorously exploring these pivotal areas, we can realize the full potential of AD, thus creating sustainable and economically viable pathways for waste valorization and contributing significantly to the establishment of a resilient and thriving circular bioeconomy. We invite researchers, practitioners, and innovators to contribute their expertise and insights to this Special Issue.

Dr. Habib Horchani
Guest Editor

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• anaerobic digestion
• intensification process
• circular bioeconomy
• enzymes
• biotransformation
• industrial biotechnology
• waste management
• environmental