Dry Anaerobic Digestion with Power Generation San Canzian d'Isonzo
BIOFerm GmbHS.Canzian d'Isonzo | Gorizia - Italy
- System description: Dry anaerobic digestion with electric power generation
- Waste processed: Mais silage, bovine manure
- Plant capacity: 28,000 tpy. Installed electric capacity 950 kW
Eleven dry anaerobic digesters are the heart of this plant that produces electric energy from renewable resources. The plant for the treatment of bovine manure and corn silage, build in San Canzian d’Isonzo, uses the process of dry anaerobic digestion, developed in a battery of fermenters arranged in a parallel formation.
The plant produces electric energy and heat from renewable sources. The quality of the treated materials is not a determining factor for the execution of the process since they can also contain inert materials, without compromising the effective functioning of the system. The plant in substance consists of the following systems:
• Digestion system, made up of 11 fermenters;
• System for the capturing and storing of the biogas;
• Co-generation system, made up of 3 gas engine units.
The fermenters are parallelepiped reactors in reinforced concrete, that are loaded by means of a mechanical loader. The mixing on entrance is made with fresh and pre-digested material derived from a previous cycle. Once the organic treatment which lasts 28 days is completed, the emptying is carried out once again by a mechanical loader. The fermenters are completely isolated from the external environment and maintained in uniform anaerobic conditions. The material originating from the agricultural company is loaded into the fermenters without any pre-treatment process. The mixing of the pre-digested material with the fresh material is a fundamental operation, because the presence of the bacteria ensures the diffusion of the same in the treated biomass. The floor of the fermenters consists of a heated base, equipped with a system for the collection of the leachate, that is re-used in successive cycles. The leachates are filtered, heated and recycled in the process by means of a series of pipes with sprinklers installed at the top inside the fermenters themselves. The process of anaerobic organic conversion is assisted by a computerised control system (PLC), that allows process to be maintained within the range of the pre-arranged parameters. Numerous variables of the process are controlled, such as for example: the temperature of the treated material, the quality and quantity of the extracted biogas and the pressure within the fermenter. A system of acquisition and visualisation of the parameters of the process allows for it to be checked in real time to see if the process is correctly executed within these parameters. All of the relevant values are memorised and can be visualised in a graphic representation of the trend of the various parameters. All equipment is installed in a dedicated building, in such a way as to minimise the overall visual impact.