Sector: Waste treatment and recovery Year of execution: 2018 Place: Valladolid
It consists of a solid digestion submerged in a 252 m³ “SOLID TANK” tank that works in synergy with a central liquid digestion in a digester with continuous agitation. The solid matter is loaded into the tank with the help of an overhead crane and flooded with the thermophilically fermenting liquid substance from the liquid digester until it is completely submerged, which will allow a uniform inoculation and a quick start of the methanisation reaction. The biogas produced in each tank is conducted and stored inside a double membrane that covers the liquid digester and allows a levelling of the biogas production. The solid digestion is thermophilic and has an adaptable residence time until the exhaustion of the biogas production (22-35 days). Moreover, during digestion, an open loop of recirculation of the liquid phase is ensured by a pump that pushes the liquid from the “LIQUID DIGESTOR” digester to the bottom of the small tank of 252 m3, which is poured into the central digester. At the end of the digestion process, a grid installed at the bottom of the tank retains the unwanted matter and solid matter so that only the “vat foot” can be recovered and transferred to the liquid digester. The excess solid digestate is extracted with a discharge ladle and deposited on a platform to allow it to drain away.