AMBIENTALIA AMBIOGAS  
 

 

Dry anaerobic digestion in amBiogas® reactors and
aerobic stabilisation of the digestate in amBiocell® bio-cells.

Ambientalia has always been committed to development of technical solutions at the service of the Environment. In the sector of the biological treatment of waste it has fine-tuned a system for the biostabilisation of residual waste destined for the dump (ambiSystem) and, subsequently, technology for management of the intensive phase of the composting process in aerated bio-cells (amBiocell). Both solutions achieve high qualitative standards of the products obtained, respectively the biostabilised waste to be dumped and the compost for soil correction.

Ambientalia aimed to take a further step, anticipating the direction that would be taken by the sector: in fact the conversion of waste into fertilizers through biological processes remains an operation of great environmental value, but the high energy consumption involved in the treatment is increasingly less sustainable. Efforts must therefore be concentrated on the possibility of exploiting the energy of biomasses and waste, an operation that becomes preparatory and not alternative to the subsequent conversion into compost. Only in this way is the virtuous circle closed: organic waste becomes an energy and agronomic resource, with a healthy balance sheet.

The result of these considerations was amBiogas, the Ambientalia technology for anaerobic digestion of biomasses and organic waste and for cogeneration of electricity and heat, applied in synergy with amBiocell, the aerobic composting technique employed for conversion into compost of the digestate residual from anaerobic processes.
 

AMBIOGAS® AMBIENTALIA®, THE STRENGTH OF AN INNOVATIVE IDEA.

AmBiogas is a technology devised, developed and patented by Ambientalia S.r.l. for the anaerobic dry digestion of waste and biomasses.

The technique of dry digestion, based on processes of fermentation of solid matrices with a dry matter content of up to 50%, has indubitable advantages of a technical nature in comparison with traditional wet digestion (DM max 10%) inasmuch as it avoids dilution of the process materials with large quantities of water; consequently there is a considerable reduction in the volumes of digestate for disposal. Moreover, management of a solid digestate is far less problematical and burdensome than that of a liquid product.

It should be pointed out that dry digestion takes place in batteries of reactors rather than in one large size digester, which means greater operational flexibility and no risk of total blocking of energy production in the case of interruptions in the biological process.

The amBiogas anaerobic dry digester fine-tuned by Ambientalia is distinguished by important features that differentiate it from other similar solutions (front loading parallelepiped module reactors).

Reactors of this type are loaded by mechanical shovels through a front opening, so the height has to be increased by about 1.5–2 metres beyond working height so that the material can be dumped from the shovel. This creates a gap between material and ceiling of about one third of total module volume. As is well known, the heat and damp emanated by the mass rise up into the empty space, and to obviate this dispersion greater energy is required to keep the mass at mesophilic temperatures (around 36°C).

In the amBiogas digester this is avoided by means of a mobile false ceiling: during filling and emptying it is raised to the height necessary for the operator to enter with the mechanical vehicle; during the process it is lowered, creating a cavity of about 300-500 mm between the ceiling itself and the material deposited in the reactor.

Using horizontal module reactor technology the most critical phases for the operators, due to the intense production of aqueous vapour and odorigenous emissions by the mass under transformation, are the loading and unloading of materials, carried out with mechanical shovels. The amBiogas digesters are equipped with a process-air suction system that creates and maintains suitable environmental conditions so that the operators can enter.

These and other solutions make the amBiogas digester a unique and highly innovative system.


Description of the reactor

The amBiogas dry digester consists of a parallelepiped module of the following dimensions: working width max 9 metres, max length 35 metres, height of internal structure in reinforced concrete 5.5 metres, height at false ceiling 5.3 metres. The structure is in reinforced concrete treated with resins to ensure airtightness and is integrated with panels in insulating materials for high heat retention.

The heaters, consisting of pipes in PE with antioxidising barrier, sunk in the floor, are fed with hot water to heat the mass. The front hatch, of the tip-up type, opening upwards by means of pneumatic pistons, is in sandwich panels of AISI 304 STAINLESS steel. Insulated internally, airtightness is ensured by an inflatable gasket. The closure system is by means of pneumatic bolts with safety lock which can be unlocked only with the ambiControl management software.

The digester has (on demand) a false ceiling which is mobile by means of pneumatic cylinders in airtight plastic material. Along the whole perimeter of the module, in correspondence to the “bed” of the false ceiling (if provided) in the lowered position, there are special closures in synthetic material which ensure the maintaining of temperature and humidity.
During loading and unloading operations the false ceiling is raised to facilitate the work of the mechanical shovel. In the course of the anaerobic process it is lowered, leaving a cavity between itself and the biomass.

To maximise working volume while at the same time protecting the hatch from the thrust of loaded material, a retaining partition is provided which is closed in the final loading phases.

The system for collecting the percolate emitted by the masses under processing consists of drainage grilles with discharge pipes where, due to the slope of the reactor floor, the refluxes converge, and of an underground storage tank for the first collection.

To ensure airtightness the “hydraulic seal” system is used, in which the discharge piping is immersed in a water trap for the first collection and send through pumps to the main storage tank. The percolate in the storage tanks is maintained at a constant, software-controlled temperature.

The digester is equipped with a sprinkler system with anti-blocking nozzles, pump-fed with percolate from the storage tanks, preheated by means of an exchanger powered by the cogenerator. Distribution of percolate on the biomass has a twofold function: microbic inoculation and the maintaining of mesophilic temperature.

As mentioned previously, the digester is moreover equipped with a forced aeration system which permits suction of the air inside the reactor to remove the foul-smelling gaseous emissions in the filling and emptying phases.

A motorised airtight valve is set between the main suction manifold and the recovery conduit from the reactor. The aspirated air is conveyed to the bio-filter for purification.
Each reactor is equipped with an autonomous suction system in order to be completely independent.

AmBiogas è costituito da moduli di larghezza variabile, che si possono integrare nell’ambiente circostante perché facili da tinteggiare.
amBiogas consists of variable-width modules which, since they are easy to paint,
can be integrated into the surrounding environment.

 

Portellone frontale
Front hatch.
Guarnizione gonfiabile per tenuta stagna
Inflatable gasket for airtightness.
Schermata del software ambiControl
ambiControl software display

> Biogas Management

> Aerobic stabilisation of amBiocell digestate

> Presentation and data sheet (PDF)

 




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