Physical-Chemical Composition Analysis of insect frass from different species produced through the bioconversion of agro-industrial waste

The objective of the present study was to develop organic fertilizers through the bioconversion of agro-industrial waste, utilizing various insect species, with the intent of evaluating both the quantity and quality of the resulting products. To conduct the research, a controlled rearing of the insect species Tenebrio molitor , Zophobas morio , and Hermetia illucens was established under laboratory conditions, incorporating diverse substrates and varying concentrations to assess the composition of the frass produced. The physicochemical characterization included analyses of moisture content, total organic carbon, pH, cation exchange capacity, and micronutrient determination via atomic absorption spectrometry, in compliance with current regulations for organic fertilizers. The primary plant nutrients, such as total carbon (36-44%), nitrogen (2.7-5%), phosphorus (2.5-6%), and potassium (1.7-3.72%), exhibited variation depending on the substrate and insect species used, with macro and micronutrient values in alignment with the requirements set forth by Brazilian and European Union legislation. Furthermore, no contaminants were detected in any of the samples analyzed. It can be concluded that the frass produced by T. molitor , Z. morio , and H. illucens demonstrates significant potential as an organic fertilizer, as its concentrations of nitrogen, phosphorus, and potassium are comparable to those found in other organic fertilizers on the market. This suggests its potential to fully replace both traditional commercial fertilizers and organomineral fertilizers, thereby contributing to a reduction in the carbon footprint associated with fertilizer production.