Biogas Production from Organic Wastes: Integrating Concepts of Circular Economy

Abstract

Anaerobic digestion is traditionally used for treating organic materials. This allows the valorization of biogas and recycling of nutrients thanks to the land application of digestates. However, although this technology offers a multitude of advantages, it is still far from playing a relevant role in the energy market and from having significant participation in decarbonizing the economy. Biogas can be submitted to upgrading processes to reach methane content close to that of natural gas and therefore be compatible with many of its industrial applications. However, the high installation and operating costs of these treatment plants are the main constraints for the application of this technology in many countries. There is an urgent need of increasing reactor productivity, biogas yields, and operating at greater throughput without compromising digestion stability. Working at organic solid contents greater than 20% and enhancing hydrolysis and biogas yields to allow retention times to be around 15 days would lead to a significant decrease in reactor volume and therefore in initial capital investments. Anaerobic digestion should be considered as one of the key components in a new economy model characterized by an increase in the degree of circularity. The present manuscript reviews the digestion process analyzing the main parameters associated with digestion performance. The novelty of this manuscript is based on the link established between operating reactor conditions, optimizing treatment capacity, and reducing operating costs that would lead to unlocking the potential of biogas to promote bioenergy production, sustainable agronomic practices, and the integration of this technology into the energy grid.

High-Solid Anaerobic Digestion: Reviewing Strategies for Increasing Reactor Performance

“…Anaerobic digestion involves several reaction mechanisms, in which anaerobic bacteria and archaea species transform biomass into a sequence of biological reactions [24]; thus, any change in operating conditions directly affects the microbiology of the system and the final outcome of the process. Ziganshin et al [25] and Langer et al [26] studied the correlation between microbial communities and parameters determining reactor performance, indicating that temperature, ammonia content, and the type of substrate had a marked effect on the diversity of these communities, fungi, and archaea organisms.…”

A micro- and macro-scale look at the biochemical methanogenic potential of the organic fraction of municipal solid waste generated in a large city of a developing country

“…AD is a biochemical process that allows for the recovery of energy from the OFMSW, in the form of biogas, which is mainly composed of methane (CH 4 ) (60-65%) and carbon dioxide (CO 2 ) (30-35%). This occurs through the following four sequential steps: hydrolysis (the breakdown of biopolymers to monomers), acidogenesis (the conversion of monomers into volatile fatty acids [VFAs] and alcohols), acetogenesis (the conversion of VFAs and alcohols into acetic acid [CH₃COOH], hydrogen [H 2 ] and CO 2 ), and methanogenesis (the production of CH 4 and CO 2 from H 2 and acetic acid) (Chaudhari et al, 2011;Jain, 2019;Rodrigues et al, 2019;Ellacuriaga et al, 2021). The co-product generated through AD is called the digestate, which is composed of the remains of the organic feedstock fed into the digester (Chaudhari et al, 2011;Jain, 2019;Hassaneen et al, 2020).…”

Estimation of Sustainable Bioenergy Production from Olive Mill Solid Waste

“…It can also help to reduce CO 2 emissions and substitute chemical fertilizers [14]. However, there are some disadvantages of biogas utilization, such as fewer technological advancements, economic infeasibility, formation of toxic intermediate composites, low production of biogas, and unstable nature of biogas [15,16]. There has been less technological progress made in making biogas production more cost-effective and feasible on a large scale due to a dearth of investors [17].…”

“…There has been less technological progress made in making biogas production more cost-effective and feasible on a large scale due to a dearth of investors [17]. Amplification of digestion plant treatment capacity is required to counterbalance the high operational and installation costs [15]. Furthermore, biogas becomes flammable and can cause explosions when it comes into contact with O 2 .…”