The conversion of existing Biogas plants is currently one of the key opportunities for the development of the agricultural Biomethane sector. Within this context, SYNERGY is developing a project for “Società Agricola Axe Agricoltura Per L’Energia” in Medicina (Bologna, Italy), where the existing plant will be expanded and converted to enable the production of 350 Sm³/h of Biomethane for injection into the natural gas grid.

The project involves a plant fed by livestock manure and agricultural biomass and includes the integration of new structures and technologies, while retaining several existing sections that are already operational and fully functional.
To achieve the project objectives, a number of activities have already been initiated, involving both process units and supporting infrastructure.
The planned structural works include the construction of a new digester, a new fermentation tank with gas recovery, new digestate storage tanks and a feedstock loading tank together with a slurry unloading tank.

From a process engineering perspective, the project includes the installation of a solid-liquid separation unit, a new upgrading plant and a desulfurization system. The intervention is completed by the infrastructure required for plant operation, including an emergency flare, technical buildings, and pumping systems.

For many agricultural businesses, Biomethane now representsthe natural evolution of the path previously undertaken with Biogas.. Projects such as the one in Bologna demonstrate how this transition can be achieved through targeted revamping and expansion activities on existing plants.

The plant, which underwent a revamp, has been converted from biogas production to the production of biomethane for injection into the grid. The works involved the construction of new gas holders, the installation of an SBR system to remove nitrogen from the digestate and to upgrade the gas, and the installation of a new biogas line with an emergency flare.

The plant consists of a primary fermenter and a secondary fermenter that allow the process to have an optimal hydraulic retention time.

Livestock waste is loaded through a pre-tank, from which it is pumped to the primary fermenter, while the plant biomass is handled through a loading hopper and a Biomix pump.

Watch VIDEO of the full realization

Input matrices

• Cattle slurry

The plant, which is currently undergoing revamping, will be fuelled by agro-zootechnical biomass (Cereal shreds and livestock manure) and by-products from the dairy industry. Thanks to the upgrading works, the plant will switch from producing electricity from biogas to producing 500 Smc/h of biomethane, which will be fed into the grid and supplied directly to an agri-food industry.

Solid biomass is fed into the system via a loading hopper fitted with a screw pump, whilst livestock manure is fed through pre-treatment tanks connected to the digesters.

Input matrices

• Livestock manure
• Cereal shreds
• Dairy by-products (SOA)

At Società Agricola Ecoenergia Cortenuova it was decided to make use of the large quantity of pig slurry (150m³ /g) produced by the company’s farms by building a 500 kWe biogas plant fed with pig manure and the addition of molasses to reach full capacity.

In addition to the single-stage biogas plant, our team built a nitrogen removal plant for the digestate downstream of the anaerobic process.
The digestate leaving the plant (about 130m³ /g ) is pumped to a screw-type solid-liquid separator to remove a large part of the solid fraction.
The clarifier is then sent to the stripping plant in the ammonia removal section.
Our system has reduced the amount of ammonia in the digestate by more than 60%.

Input matrices

• Pig slurry 150m³/g
• Molasses

Watch VIDEO of full realization

Input matrices

• Pig slurry
• Maize silage
• Triticale

In 2021, Synergy installed a 500 Sm3/h biomethane plant that feeds gas into the grid.
The plant consists of two primary digesters with four mixers each and two secondary digesters with three mixers each.
The liquid biomass is stored in two pre-tanks, while the solid part is fed into two hoppers with a shredding system. Afterwards, the solid fraction is mixed with the liquid part and together conveyed to the primary digesters.
The digestate is then sent through pipes to the separator to make the division between the liquid and solid parts, which can be used as organic fertiliser.
Our technicians and software engineers installed a PLC with software capable of managing the entire plant in the technical room.

Input matrices

• Silage
• Sorghum
• Triticale
• Corncobs
• Cattle manure
• Poultry manure

The biological sludge from the newly constructed plant is pumped into a single-stage fermenter. The biogas produced is sent to a cogenerator installed in a room that will produce electricity for the purification plant’s own consumption. Such a plant, having as its feedstock a material quite different from slurry, biomass or other product, uses different, specially designed components.

This plant is a demonstration of Synergy’s ability to develop different systems using waste types of various origins.

Input matrices

• Biological sludge

• Pig slurry

Input matrices

• Cattle slurry