Montello S.p.A.’s plant can receive and process 165,000 tons/year of waste of organic origin, including the organic fraction of solid  urban waste (FORSU).

The adopted plant solution consists in an initial waste pre-treatment phase, followed by anaerobic digestion (aimed at the production of biogas used for the generation of electrical and thermal energy), and a subsequent aerobic composting phase of the sludge coming from the dehydration of the digested waste, aimed at the production of quality organic fertilizer.

Montello started to process waste of organic origin back in the 1990s, with the initial target  of obtaining a simple “sanitation stabilization” aimed at  the disposal in the landfill.
In 1997, it developed an aerobic composting treatment for the production of "composted mixed soil improver".

The markedly industrial connotation of Montello, the potentiality of its plant and infra-structural equipment, the constant search for technological innovations and the willingness to experiment with new methods, have prompted the Company to implement constant adjustments and improvements to the plants through the years, according to a logic that goes beyond the horizons of local-scale “environmental services”.

The experience gained in managing the fully-aerobic composting process has allowed the company to identify as “crucial phases” of the processing the pre-treatment of the organic fraction of the waste (for the purpose of separating foreign materials – such as plastic, glass, metals, etc. – from the organic fraction – prior to the bio-converting) and the phase defined as "ACT", that is the period with the greatest fermenting activity.

The results achieved have led the Company to search for new technologies and, consequently, to make an investment that would considerably improve the existing intensive aerobic treatment through the introduction of pre-treatment and anaerobic digestion phases of organic waste. The adopted process is WET type, in a continuous stirred tank reactor, or CSTR, with the use of the biogas produced by the anaerobic digestion process in electro-thermal co-generation groups.

Anaerobic digestion, which is also well-known in Italy for a long time to stabilize biological sludge, is not very popular in the treatment of waste of organic origin, contrary to what is happening in the rest of Europe.

The advantages offered by the anaerobic treatment concern multiple aspects, the main ones being summarized as follows:

• Energy requirement: energy requirement decreases by passing from the aerobic treatment to the anaerobic one; in fact, as we all know, the anaerobic treatment is, vice versa, a source of positive energy;
• Field of application: wide field of application (no problems tied to the presence of foreign materials or excessive humidity);
• Flexibility: the same plant can process different types of organic waste;
• Automation: plant operation is entirely automatic, including the separation of foreign materials (manual selection not required);
• Energy: maximum recovery of both electric and thermal energy, thanks to the high yield of the multi-phase process;
• CO2 emissions: organic material is converted into energy, contributing to a reduction of CO2 emissions and consequently to a reduction of the greenhouse effect;
• Environmental impact: absolutely limited. The process takes place inside buildings kept in depression, hermetically sealed tanks and piping, eliminating any odorous emissions outside and inside the plant and maintaining optimal conditions in the workplace. The use of bio-filters to treat the exhausted air of the plant allows a complete abatement of the emissions into the atmosphere.