Circular-BioEconomy Through Anaerobic Digestion

Global warming and the rapid depletion of natural resources raised concerns about our traditional method of economic activities. Many ideas and models about resource-friendly production and consumption have been developed and experimented with. One of the models, circular economy has gained traction as it promotes efficiency in the utilization of resources. The circular economy is an open concept, it is still being developed. Attempts have been made to adopt a circular economy in many fields. In this chapter, we explored the circular potentiality of the anaerobic digestion system. We studied the status of bio-hydrogen and bio-methane production using different types of organic wastes and two circular anaerobic digestion models: Co-Digestion of Various Organic Wastes and Utilization of CO2 Emissions from Anaerobic Digestion. It was found that anaerobic digestion can bring organic wastes into circularity by using it as feedstock to produce bio-methane which can replace a significant amount of fossil fuel to produce electricity and liquid transport fuel, as well as can create jobs and the digestate can replace fertilizers; combinedly these features reduce CO2 emission too. Although bio-hydrogen showed technical potential, this tech-nology is still in the laboratory phase. We attempted to justify our study with relevant case studies. Finally, we discussed the challenges and prospects of anaerobic digestion as a tool of the circular economy. A successful commercial circular anaerobic digestion system needs to address several key technological aspects. As it has a great deal with waste management and circular economy requires the active involvement of every stakeholder, socio-political challenges should be addressed with equal importance.