Soil washing plant
The waste deriving from street sweeping accounts for around 5-10% of total urban waste in generai. Given quantities of this order, the identification of technologies allowing this material to be recycled is more than justífied.
A2A Ambiente Spa, an A2A Group company, has carried out a technical and economic feasibility study which has given a positive outcome, and also revealed considerable environmental benefits, in view of the high percentage of aggregates (sand and gravel) which can be recovered by this process. Moreover, the plant implements the principles contained in the EU and Italian regional and provincial Directives, since it generates a reduction in the amount of waste for landfill disposal and puts the principle of environmental sustainability into genuine practice, with processes which recover more than 6o% of the waste entering the system.
The processing capacity of the plant constructed in Brescia is about 30,000 tonnes of incoming waste per year and it is the second plant in Italy to be built with these characteristics.
The innovative, extremely advantageous features of this plant, designed on the basis of a large number of experimental trials, are as follows:
- backflow soil washing unit;
- cyclone unit with spirai separators;
- chemical-physical-biological treatment plant for recycling of the water from the washing process.
The washing system transfers the substances present in dissolved or emulsified form, or in suspension, from the soil particle to the water. The particles of solid pollutants are then separated by means of additional sorting processes. Finally, the process water is treated in a special chemical, physical and biological treatment plant.
This innovative treatment is able to process the waste obtained from street sweeping operations to produce materials of certified quality, which would previously have simply been sent for disposal in a landfill. Therefore, on the one hand the plant reduces landfill use, while on the other it cuts the need for sand and gravel from new quarries.
The products leaving the plant pass the tests for compliance with the UNI EN standards for their specific sector of use: UNI EN 72620 -Aggregates for concrete; UNI EN 73043 - Aggregates for bituminous mixtures; UNI EN 73739- Aggregates for mortar; UNI EN 73242 - Aggregates for civil engineering works.
The materials which can be recycled bytreatment of the incoming waste are therefore materials which can be sold throughout the European Union, since they carry the CE Mark. CE marking provides the consumer, meaning the purchaser, with a guarantee that the products marked meet essential safety requirements and have passed the tests envisaged by the standards.