Anaerobic co-digestion of agricultural wastes toward circular bioeconomy

Abstract

Summary A huge amount of agricultural wastes and waste activated-sludge are being generated every year around the world. Anaerobic co-digestion (AcD) has been considered as an alternative for the utilization of organic matters from such organic wastes by producing bioenergy and biochemicals to realize a circular bioeconomy. Despite recent advancement in AcD processes, the effect of feedstock compositions and operating conditions on the biomethane production processe has not been critically explored. In this paper, we have reviewed the effects of feedstock (organic wastes) characteristics, including particle size, carbon-to-nitrogen ratio, and pretreatment options, on the performance of an anaerobic digestion process. In addition, we provided an overview of the effect of key control parameters, including retention time, temperature, pH of digestate, volatile fatty acids content, total solids content, and organic loading rate. Lastly, based on the findings from the literature, we have presented several perspectives and prospects on priority research to promote AcD to a steppingstone for a circular bioeconomy.

Valorization of agro-industrial wastes for biorefinery process and circular bioeconomy: A critical review

“…Anaerobic digestion involves the degradation or decomposition of organic matter such as agri-waste, food-waste, etc in absence of oxygen to produce products (Pan et al, 2021). Methanogenesis, acidogenesis, hydrolysis, and acetogenesis are the four main processes involved in anaerobic digestion.…”

Indicative Marker Microbiome Structures Deduced from the Taxonomic Inventory of 67 Full-Scale Anaerobic Digesters of 49 Agricultural Biogas Plants

“…However, in the past two decades, more than 9500 biogas plants in Germany have mainly been operated with energy crops (48.9%) and livestock manure (44.5%) [13], which are mainly co-digested to enhance the digestion process and thus increase biogas yields [14]. According to the current efforts of developing a bio-based circular economy (German National Bioeconomy Strategy, https://biooekonomie.de/nationale-biooekonomiestrategie, accessed on 5 July 2021), there will be a transition to a residue-based biogas production.…”

Investigating microbial dynamics and potential advantages of anaerobic co-digestion of cheese whey and poultry slaughterhouse wastewaters

“…Alternatively, the high organic load can be converted to energy as methane via anaerobic digestion. Based on this, the use of anaerobic digestion to treat both wastewaters is aligned with global initiatives focusing on renewable energy and circular economy 4 – 6 . The amount of recoverable energy in cheese whey and poultry slaughterhouse wastewaters is estimated at 24,500 and 12,200 GWh/year, respectively, or about 11% of the total energy contained in all agro-industrial effluents 1 .…”