The project PARMORIZZAZIONE achieved the expected result of using the digestate from bovine manure coming out of a biogas plant for a further concentration in the SSICA prototype. An ammonia fraction (85%) was obtained, with a concentrate destined for pyrolysis (15%) as a residue. The ammonia fraction was further concentrated by reverse osmosis into a fertilizer (9-10%). The concentrated residue was subjected to pyrolysis in a second prototype plant, mixed with dry biomass of vegetable origin. The biochar obtained from digestate or concentrate can be used as a soil improver as it does not show phytotoxicity and is a phytostimulant for barley growth. The agronomic tests compared biochar, ammonium salts and conventional fertilization on barley (cv Concerto), tomato, wheat (cv San Pastore), protein pea (cv Hardy). The results highlighted some critical aspects in the distribution of materials, which depend on the characteristics of the soils and climatic conditions. For example, the drought of 2019 strongly changed the response of crops. The feasibility of extracting useful chemicals from tar that is obtained as a further by-product from pyrolysis, a material that is not yet fully exploited, remains to be explored. In fact, the economic analysis was based only on ammonium salts, biochar and energy, demonstrating the positive aspects of a management that disposes of the digestate directly on the farm. The project produced guidelines to address the interested parties.
The integrated use of the two prototypes will allow the extraction from the solid part of the digestate of:
• A fertiliser containing ammonium salts and a non contaminated amendment which provides nutrients and structural benefits, improving soil fertility, increasing retention of water and of nutrients, particularly calcium, potassium and phosphorus.
• A fuel: the syngas
• Plyphenolic compounds (biomolecules with high added value), which can be used in the food industry, with an antioxidative function to protect cells from damages provoked by free radicals.
DESCRIPTION OF PROJECT ACTIVITIES
• Digestate Collection and storage
• Digestate treatment using two prototypes (“evapoconcentratore” carbonizer): the combined use of the two prototypes will enable the conversion of the digestate into a fertilizer, organic fertilizer and nitric acid; in energy from renewable sources with low emission of pollutants and antioxidants contained in the bio-oil fraction (tar), obtained as a result of pyrolysis, for their reuse for food purposes.
• The use of biochar as a soil enriched agronomic rating.
• Laboratory analysis to characterize the products obtained.