ETVO, located in São Brás, in the municipality of Amadora, is Valorsul's operational unit that receives, treats and valorises organic waste collected from large producers (restaurants, canteens, hotels, markets, hypermarkets).

Organic waste from the different sources is delivered to the Centre during two shifts: from 00:00 to 08:00 and from 16:00 to 24:00. It is deposited in a reception and unloading area, confined and equipped with isolation doors suitable for vehicle access.

The organic waste deposited in the wet line reception pit is transported by a set of screw conveyors, whose bed has a sieve mesh (150x60mm), through which the smaller organic waste passes. The smaller organic waste is fed via screw conveyors to the hammer mills (3) with the addition of process water upstream. The hammer mills generally consist of a set of knives (136) supported on a shaft that rotates by the action of an electric motor and an 18 mm mesh screen, which ensure the crushing (decomposition) and particle size reduction of the waste, producing an organic suspension that is stored in a tank located below the mills. This equipment is made of stainless steel and has a nominal capacity of 7 t/h (each).

ETVO was the first facility in Portugal to use ‘Anaerobic Digestion’ technology (treatment in a closed environment without oxygen) associated with ‘Composting’ and to produce electricity from the biogas generated. In addition to this energy, which is exported to the National Electricity Grid as ‘green energy’, high-quality ‘compost’ is also produced for use in agriculture.

The biogas produced is stored in a reservoir measuring 2,150 m3.

All the contaminated air from the plant is collected (6 air changes/h) and treated in the biofilter, thus preventing the spread of odours in the ETVO and the surrounding area.

To obtain the final compost, it still goes through a refining process, the aim of which is to remove the wood chips, which we will use again in the process, and to remove some contaminants that were not removed in the pre-treatment phase. The end product is an excellent natural fertiliser as it provides organic matter to agricultural soils and helps retain water from irrigation and rainfall near the roots of plants. 4 months is the time between receiving the waste and obtaining the final compost.