Characterization of composted organic solid fertilizer and fermented liquid fertilizer produced from the urban organic solid waste in Paipa, Boyacá, Colombia

Purpose Urban organic solid waste (UOSW) has great potential to be transformed into solid and liquid organic fertilizers, thus avoiding its accumulation in landfills and reducing the environmental impact caused by the generation of gases and leachates. Therefore, the purpose of this research was to study the management of the UOSW in the municipality of Paipa as raw material for obtaining solid organic fertilizer through composting and a liquid fertilizer through fermentation. Method The UOSW of Paipa was combined with inorganic salts such as carbonates, phosphates, sulfates and source of carbohydrates to enrich its bacterial load and chemical composition. The content of essential nutrients that contribute to good soil-plant synergy, heavy metals and pathogenic microorganisms  in the primary and final material were determined. Results The experiment showed a high COO load, between 24-35%, and similar values in  organic N content in the primary materials. Heavy metals were found below the minimum allowed by the CTS 5167 of 2011 for the organic solid residue, and no pathogenic microorganisms were found. Composting and fermentation processes improved the physical-chemical properties of the materials; however, the liquid mineral organic fertilizer did not comply with the established parameters, while the solid one was in compliance with the requirements. Conclusion After a period of 4 months, the study showed that solid UOSW from the municipality of Paipa can be used as a potential source for producing organic fertilizers by adding nutrients in mineral forms, complying with the nutrient requirements for plants and soil feeding organisms.