Anaerobic co-digestion process for biogas production: Progress, challenges and perspectives

Globally, there is increasing awareness that renewable energy and energy efficiency are vital for both creating new economic opportunities and controlling the environmental pollution. AD technology is the biochemical process of biogas production which can change the complex organic materials into a clean and renewable source of energy. AcoD process is a reliable alternative option to resolve the disadvantages of single substrate digestion system related to substrate characteristics and system optimization. This paper reviewed the research progress and challenges of AcoD technology, and the contribution of different techniques in biogas production engineering. As the applicability and demand of the AcoD technology increases, the complexity of the system becomes increased, and the characterization of organic materials becomes volatile which requires advanced methods for investigation. Numerous publications have been noted that ADM1 model and its modified version becomes the most powerful tool to optimize the AcoD process of biogas production, and indicating that the disintegration and hydrolysis steps are the limiting factors of co-digestion process. Biochemical methane potential (BMP) test is promising method to determine the biodegradability and decomposition rate of organic materials. The addition of different environmentally friendly nanoparticles can improve the stability and performance of the AcoD system. The process optimization and improvement of biogas production still seek further investigations. Furthermore, using advanced simulation approaches and characterization methods of organic wastes can accelerate the transformation to industrializations, and realize the significant improvement of biogas production as a renewable source and economically feasible energy in developing countries, like China. Finally, the review reveals, designing and developing a framework, including various aspects to improve the biogas production is essential.