Agricultural valorization by biotransformation of fish wastes combined with grape marc and molasses

Since the advent of agriculture, organic wastes have been used to fertilize agricultural soils. The sustainability of the recovery of these wastes depends on the quality of the products developed in order to meet the expectations of the agricultural profession. The objective of our study was to evaluate the quality of the biotransformation of a ternary mixture of industrial waste: fish waste, molasses, and grape marc. Several balanced mixtures were developed and underwent natural biotransformation for two weeks to produce a fertilizer of good nutritional and microbiological quality. Quality control parameters (pH, conductivity, dry matter, phosphorus, nitrogen, potassium, carbon, etc.) were monitored during the time stipulated for biotransformation. The results showed that the bio-fertilizer generated from the mentioned wastes is characterized by good agronomic quality (rich in phosphorus, nitrogen, and potassium), mature, with a stable pH and had an excellent hygienic condition, due to the absence of spoilage microorganisms, which would constitute a major obstacle to the adoption of this practice. The fertilization test showed that our product is more interesting than commercial fertilizer. Triangular surfaces of iso-responses are established to identify the relevant formulations leading to a product of specific interest to build in practice a predictive operational model for industrial waste management. The biotransformation of a mixture consisting of approximately 50% of fish waste, 12.5% molasses, and 37.50% grape marc is an optimal formulation to generate a product rich in the nutrients essential for optimal growth plants (nitrogen, phosphorus, and potassium). The formulas do not integrate the grape marc was the most unfavorable mixtures from their efficacy and/or health safety criteria.