Valorization of Hydrobiological Waste through Anaerobic Fermentation for Biofertilizer Production

Abstract

This study concerns the production of liquid biofertilizers by anaerobic fermentation of hydrobiological residues of A. purpuratus (Peruvian scallop), Oreochromis sp. (tilapia), O. mykiss (rainbow trout), and various marine wastes at concentrations of 20 %, 40 %, and 60 % (w/v), employing the commercial microbial consortium Garlac as inoculum. The objective was to characterize their physicochemical and microbiological properties and to assess their agronomic efficacy on Zea mays L. growth. Fermentation was achieved within 10 days, yielding biofertilizers with elevated organic matter content (83.83–97.74 %), organic carbon (48.63–56.70 %), and NPK concentrations of 0.50–1.19 % of N, 0.10–2.76 % of P, and 0.04–0.66 % of K. Germination bioassays demonstrated low phytotoxicity at 10-2 and 10-3 dilutions (germination index > 80 %), whereas the 10-1 dilution exhibited severe phytotoxicity attributed to acidic pH (3.95–4.57) and elevated electrical conductivity (22.40–32.40 mS/cm). Greenhouse trials revealed that biofertilizer applications enhanced maize plant height by 11.54–54.96 % relative to chemical fertilizer treatment after 60 days, with the 60 % marine waste biofertilizer distinguished by superior nitrogen content (1.19 %) and the 60 % tilapia biofertilizer by higher phosphorus concentration (2.76 %). The findings substantiate that valorization of hydrobiological wastes through anaerobic fermentation generates efficacious organic biofertilizers, thereby supporting Circular Economy principles within aquaculture and fisheries sectors. Copyright © 2026, AIDIC Servizi S. r. l.