Biogas production by means of livestock compost in a Sicilian zootechnical farm

The concept the “circular economy” focuses on the conscious and sustainable management of waste products, to reuse them in a more efficient way, re-introducing them into the production cycle as “secondary raw materials”, instead of adopting a simple waste disposal treatment. In this way, the products' lifecycle is extended to ensure a new use. The aim of this paper is to analyze the anaerobic digestion techniques used to obtain small-scale biogas, with the purpose of incorporating together the production, industrial collection and management systems’ and the amount of the sewage produced by the livestock company “Azienda Agricola Mulinello Srl”, located in the Sicilian hinterland. The company owns a close-loop pig farm of 5,000 livestock units (ranging from 110 to 120 Kilograms), its own slaughterhouse, a meat processing laboratory, a production plant for cured meat, a feeding system and a composting plant for processing effluents. The entire establishment has got a circular economic system. The anaerobic digestion system becomes particularly important in the “circular" view, as it allows the re-use of processed effluents and organic waste by their transformation into biogas and bio-fertilizers. This is the reason why the company plans to install an anaerobic fermentation plant for the autonomous production of electricity and heat to be re-used within the factory itself, and also to redeploy processed sewage as organic fertilizer. The company could obtain several positive results from this plant, such as: the reduction of waste products, a decrease in disposal costs, possible income from the sale and exploitation of the so-called “digestate”, and the participation in European incentive plans for the production of renewable energy. In the long run this method, which exploits effluents, will not only provide the company with savings, but it will also represent benefits both in terms of financial earnings and health.