Valorizing municipal organic waste to produce biodiesel, biogas, organic fertilizer, and value-added chemicals: an integrated biorefinery approach

Economically viable alternatives for utilizing municipal solid waste are still a major challenge for society, especially in less developed countries. A potential pathway is using the organic fraction of municipal solid waste (OFMSW) to produce energy, biofuels, organic fertilizers, and value-added chemical compounds. We evaluated an integrated biorefinery structure for the treatment of used cooking oil, pruning biomass, and organic and food residues to produce biodiesel, biogas, organic compost, 1,3-propanediol, and electrical energy at the campus of the Federal University of Pernambuco, which was considered a case study to represent a small city of Northeastern Brazil. A pilot transesterification plant, a biodigestion unit, and a compost unit were installed to process 3.3 tons daily of OFMSW produced. Additionally, research was carried out to produce 1,3-propanediol on a laboratory scale from residual glycerol. The quality of the biodiesel generated from the used cooking oil met national technical standards and the conversion of residual oil into biodiesel reached 93%. The average biogas production was 0.584 ± 0.176 Nm3 kgVS−1, with an average methane production of 50% generating up to 44 MWh of electricity per year. The organic compost produced met the quality requirements of organic fertilizers, such as maturation and nutrient contents. Glycerol treatment increased the yield of 1,3-propanediol production. Our findings demonstrate that the integrated biorefinery will lead to a reduction of US$ 80,000 in the costs of OFMSW management. More importantly, this approach generates incentives for circular economy initiatives in small municipalities in Brazil and other less developed countries.