Evaluation of ammonia and GHG emissions from frass in agricultural biogas systems

SCARPECI TELMA ELEONORA; ROLLÈ LUCA; DELA PIERRE FLAVIA; FRIULI MARTINA; DINUCCIO ELIO

Napoli

Workshop; IEEE International Workshop on Measurements and Applications in Veterinary and Animal Sciences; 2023

IEEE

A novel way to valorize organic wastes is the treatment with Black Soldier Fly (Hermetia illucens) larvae, in which organic residues are converted into larval biomass that can be used as a source of protein in animal feed. A by-product of larval rearing is frass, which could be used as a substrate in anaerobic digestion to produce biogas or as an organic fertilizer in agriculture. The goal of this study was to analyze the environmental impact of using frass and its digested form after the anaerobic digestion process as a soil amendment. Firstly, the study focused on obtaining the digestate from frass (FVF) and the cattle manure used as a reference (BM) and evaluating the biogas and methane produced from both biomasses. No difference in biogas and methane production, in terms of mL g VS-1, was observed comparing FVF with BM. In the second part of the experiment, greenhouse gases (CO2, CH4, N2O) and ammonia (NH3) emissions were evaluated when the soil was fertilized using FVF, BM, and the digestates D-FVF and D-BM. Ammonia emission from BM was 6.25 kg ha-1, which was statistically higher than the values obtained for D-BM (4.60 kg ha-1), FVF (4.62 kg ha-1), and D-FVF (4.27 kg ha-1). Even though there was no statistical difference in the amount of N2O, CO2, and CH4 emitted by the samples, the contribution from each gas to the Global Warming Potential (GWP) made these values differ significantly. GWP values, expressed in CO2eq, were higher in FVF (547.81 kg ha-1) and D-FVF (428.75 kg ha-1) than in BM (183.80 kg ha-1) and D-BM (249.70 kg ha-1)