Slaughterhouse waste and dead animals are mainly disposed of by incineration, which generates greenhouse gases and NOx. These wastes are a source of nutrients that can be recovered by circular economy techniques if material recycling is given a priority over energy recovery. To valorize high-protein animal waste (containing bones, meat, feather) for fertilizer purposes, the waste was processed by acid solubilization and neutralized with potassium hydroxide solution, which yielded a liquid fertilizer with plant growth biostimulating properties (due to the amino acids presence). The composition analysis showed that new fertilizers met all quality requirements set by the law, contain ~0.5% m/m amino acids and are microbiologically pure. The fertilizer was enriched with microelements to the level of 0.2% m/m and tested for biological effectiveness in germination tests and field studies. Compared with the commercial formulation, the fertilizer increased stem length and chlorophyll content (by 8.2% and 27.0%, respectively), wheat crop yield and grain micronutrients density (Cu by 31.2%, Mn by 10.5%, Zn by 33.9%) and improved the wheat flour baking properties. The described solution propose a safe way to utilize hazardous waste via technological mobile installation, enabling no transportation of waste, which is an important aspect of sanitary-epidemiological risk minimization.
Keywords: Breaking properties; Chemical solubilization; Hazardous waste; Slaughterhouse waste; Waste valorization.
Copyright © 2021 Elsevier B.V. All rights reserved.