Idrodepurazione - Agri Power Anaerobic Digestion Plant
The Agripower plant is based on the process of anaerobic digestion of input, where organic substances are degraded by micro/organism in the absence of oxygen (anaerobic condition) at a temperature of approximately 35°C-37°C (mesophil process) or at 50-55°C (thermophilic process). The input biomass (derived from farming and agriculture) is pumped into a pre-treatment area. The mixture then passes to a highconcentration, wet digestion process. The sub-products deriving from anaerobic digestion are biogas and digestate. Biogas is a gaseous mixture mainly composed of methane and carbon dioxide, suitable for the combined production of electrical and thermal energy. Digestate is the output sludge resulting from the anaerobic digestion and is separated into two fractions: a solid one and a liquid one.
DESCRIPTION OF THE PLANT
The input material is sent to a high-efficiency pre-treatment area for grinding and mixing.
A dedicated, PLC-based software allows to constantly monitor the quantity of organic material and raw materials needed to ensure high-quality biogas production.
Anaerobic digestion for biogas production
The output biomass passes to a high-efficiency anaerobic digestion area, where the organic material is degraded and gas is produced under constantly controlled mixing and temperature conditions. The anaerobic digestion process takes place inside digesters. Sludge mixing in the digesters is granted by specifically designed mixers to guarantee that the liquid fraction is adequately mixed even at high concentration levels. Process temperature is controlled through special tubular heat exchangers using the cooling water of the combustion engine inside the cogeneration units. The output biogas contains approximately 50-60% of methane, which is stored inside gasometers located on the top of the digesters, including gasometric membranes of different volume. The plant also includes a biogas organic desulphurization system inside the anaerobic digester with oxygen concentration control.
The output gas is then sent to a cogeneration unit for the combined kickback of electrical and thermal energy. The cogeneration unit is composed of an endothermal engine directly coupled with a power unit. Output energy, the output of wich is equal to 38-42% of input energy, is channelled through a transformation chamber to the national network. Thermal energy is recovered from the engine cooling cycle: it is in part used to heat the digesters and part stored for other purposes.
Separation of digested solid and liquid fractions
The output product deriving from the digestion process is sent to a revolving separator, the purpose of which is to separate the liquid fraction and the solid fraction. The liquid fraction can be stored in specifically designed tanks or sent to treatment or disposal. The solid fraction can be piled on concrete flooring. They can also be spread over land during the appropriate period. In compliance with the Nitrates Directive, nitrogen in excess can be removed by subjecting the liquid digestate fraction to a denitrification treatment.
Controller, process control and supervision system
The entire process is controlled through a centralised measurement and regulation unit and an automated supervision and process control system.
This equipment is installed in a centralised technical room, easily accessible to facilitate supervision, control and maintenance operations.
Energy generated from biomass, leading to the release of the green certificates, represents a new and highly efficient SOURCE OF INCOME. The GREEN CERTIFICATES grant a shortterm economic return and is years of proven plant duration. The INVESTMENT is commensurate with plant expected profitability. The INVESTMENT is safe, because traditional energy sources will gradually deplete and the need for energy generated from renewable sources will proportionally increase.
The transformation of zoo-technical wastewater into stable organic material reduces odours, resulting in nitrogen reduction.
Energy generated from anaerobic digestion is considered BIOENERGY. Biogas is considered a low environmental impact energy source.
- cereal flour
- agricultural waste
- bovine slurry
- bovine manure
- pig manure
- horse manure
- goat manure
- ovine manure
- fowl dung
- sludge from depuration
- fruit and vegetable waste
- food and farm waste
- canteen waste
- butcher waste
- seafood processing waste