The effect of addition of the nutrit

The effect of addition of the nutritional mix on the primary substrate was tested in a continuous laboratory reactor that faithfully reproduces the operation of the anaerobic fermenter on an industrial scale. This experimental campaign was preceded by the design, development, and testing of the system, aimed at assessing the suitability and functionality of the system itself. The reactor (Figure 1) (Maufacted by BioBooster Srl, Italy) consisted of a cylindrical stainless-steel tank equipped with a supply duct placed on the upper part of the cylinder itself and a recirculation duct equipped with an external pump that allows the mixing of the substrate. On the upper part of the reactor two pipes were placed for the installation of a pressure data acquisition system and a biogas venting system. On the side wall of the cylinder a temperature sensor was placed. The reactor was also equipped with a valve and an outlet pipe for expelling the digested material. The reactor was emptied by a valve at the base of the cylinder itself. The heating system was electric with manual temperature adjustment. The maintenance of a constant temperature during operation was guaranteed by the presence of a layer of insulating material that was wrapped around the reactor and the recirculation duct.