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Anaerobic digestion (AD) technology has become increasingly important due to its contribution to sustainability and a circular bioeconomy. While AD technologies are widespread in developing countries, developed countries have mainly driven research. The aim of this research is to analyze the biogas sector development from the point of view of a developing country like Colombia. AD research ranges from laboratory mesophilic AD to psychrophilic full-scale digesters, which are intergrated with household farms as a thermal energy source for cooking, nutrient recycling for agriculture, and waste management. Research on agricultural waste substrates, inocula, and co-digestion has dominated the Colombian publications, while full-scale digesters performance research is incipient. A survey of installed digesters collected information about 996 systems and found that 79% were psychrophilic low-cost tubular digesters. Regulations for biogas were reviewed, and it was found that they are not adequate for low-cost digesters and are inherited from developed countries, ignoring the national context. Five case studies are presented on the characterization of AD technology experiences, analyzing barriers and opportunities for the technology. National networks that include farmers, NGOs, and academia are driven slowly by Colombia's widespread AD technology, mainly on small-to medium-scale farms. • Half of the Colombian AD publications are from the last three years. • 79% of the digesters are low-cost and run under psychrophilic conditions. • Mesophilic AD research on substrates, co-digestion, and inoculum dominates. • There is a lack of regulation, support, and psychrophilic AD research. • Multidisciplinary networks drive the spread and research of low-cost digesters. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) has been a widely tested alternative for the management and valorization of wastewater from the animal slaughter process. However, the integration of AD in slaughterhouses depends on technical and economic aspects. In Colombian slaughterhouses AD integration is limited by the availability of land. In the present study, a techno-economic evaluation of the AD of offal wastewater (OWW) stream in a laboratory scale mesophilic tubular digester was carried out. The digester was operated at organic loading rates (OLR) of 0.28, 0.50, 1.0, 1.5 and 2.0 kg VS/m 3 d. Boilers and a CHP (combined heat and power) system were considered for energy integration of biogas. For the economic study, the cost structure of a Colombian slaughterhouse was considered. The AD of OWW at 2.0 kg VS/m 3 d OLR was unstable with risk of inhibition. Increasing the OLR from 0.28 to 1.5 kg VS/m 3 d caused a reduction in the specific biogas production (SBP) from 0.474 to 0.069 m 3 /kg VS However, the biogas production rate (BPR) remained constant at around 0.105 m 3 /m 3 dig d for OLRs > 0.28 kg VSm 3 d. Therefore, OWW anaerobic digestion in low-cost mesophilic biogas plants is technically feasible with OLRs between 0.28 and 1.5 kg VS/m 3 d. The implementation of boilers is economically favorable for OLR ≥ 1.0 kg VS/m 3 d. Nevertheless, feasibility is very sensitive to variations in the cost structure. The implementation of CHP was feasible in the range of OLRs evaluated and its viability is not affected by changes in assumed costs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper: [Zamir reports financial support was provided by Colombian Departamento Administrativo de Ciencia, Tecnología e Innovación (Colciencias)]., (Copyright © 2023 Elsevier Ltd. All rights reserved.)