Optimized pre-treatment of the food waste used is decisive for the efficiency of the overall facility and for the quality of the biogas and solid and liquid fertilizers produced. To achieve this, Anaergia combines two highly powerful systems at its Cardiff facilities. The first step consists of using a db-Bag Opener to tear open the waste bags delivered to the plant waste and then prepare the waste for further processing.
Next, an Anaergia BioREX 300 high-pressure extrusion press reliably separates the waste into organic and inorganic components. Water is added to this to create a pumpable fermentation substrate that has been optimized for the fermentation process and that contains less than 3% inorganic substances. The share of organic substances in the separated inorganic fraction is less than 5%.
Anaergia has implemented leading biogas technology from its German subsidiary in the fermenters. This ensures a maximum biogas yield with minimum energy consumption. PSM submersible mixers with intelligent motor control (DMC), a high torque (up to 800Nm), and carefully developed mixer blade geometry ensure the best possible flows with gentle metabolism/gas exchange for the bacteria and uniform through mixing of the entire fermenter contents. The mixing process is optimized and the hydraulic retention time (HRT) is extended.
Anaergia Technologies service boxes enable service and maintenance of the mixing technology without opening the roof and thus without any methane escaping. The biogas produced is treated using biological desulfurization and is then dried before being used in the CHP to produce clean electricity and heat. The digestion process ends with pasteurization and a high- end Anaergia Technology filter screw press (FSP) separating the fermentation residues or digestate into solid and liquid fractions.
The liquid fraction meets the stringent British Standards Institution (BSI) Publicly Available Specifications (PAS) 110 standard which allows for less regulated use of the organic fertilizer.