Logo stampa

Pisa Stabilisation Plant

Via C. L. Ragghianti, 12 - Pisa

  • 1 / 1   

Herambiente Servizi Industriali

Page updated 1 July 2019

    Authorised treatment capacity
    the maximum quantity of waste authorised for treatment is 55,000 t/year, of which 45,000 t/year of hazardous waste.
    Authorised storage capacity
    600 tonnes.
    Waste accepted
    liquid special waste, hazardous and non-hazardous waste. Waste from outside the region is also authorised.

    The plant has a potential of 25 t/h and consists of:

    • a storage section made up of special bays for unloading and transferring the waste to be treated and of dust storage silos;
    • a preliminary mixing section consisting of two discharge, homogenisation and mixing tanks, into which some specific reagents can also be dosed a mechanical mixing section consisting of a loading hopper equipped with a tilting screen, conveyors and augers for transporting and dosing reagents and waste and two mixers (of which only one installed, at present);
    • o a maturing area.

    The treatment uses the setting process of cement or lime and other reagents (silicate, bentonite, phosphoric acid, sodium sulphide (flakes or liquid), organic thickeners, silicoaluminates, etc.) to trap pollutants.
    The sludge to treat is discharged into the storage bays from which it is sent by bucket to the mixing and homogenisation tank.
    Dust, on the other hand, can be delivered both in big-bags and in bulk. Bulk dust is unloaded directly into the storage silos from it is fed with a closed system to the stabilisation plant. The sludge-dust mixture is fed to the mixer, which is equipped with two mixing shafts, each equipped with a 55 kW motor (for a total of 2 motors), through a loading hopper equipped with a tilting screen that performs a preliminary coarse screening. The necessary reagents (lime, cement or sodium sulphide or other specific reagents) are then added to the mixture. The solid parts separated by a tilting screen are stored in a container to be sent off for disposal.
    The stabilised waste is finally discharged into the maturation bays located in the northern part of the plant where it remains in maturation, before it is sent to its final destination.
    The matured sludge is subjected to laboratory analysis in order to check the successful outcome of the process. The final destination of the sludge can be landfill or incineration.
    The air of the whole area is drawn out by a special fan and conveyed outside after filtration on a bag filter and passing through a dedicated biofilter.
    Solid reagents are stored in a special silo equipped with a dust filter or in big bags/bags, while liquid reagents can be stored in the two 15 m3 tanks on the plant and connected to the mixer with a dosing pump, or in palletized containers (such as small cisterns).
    The stabilisation plant can also be used, if necessary, for simple solidification of waste, by mixing waste of different consistencies.

    Waste type approval
    Specific waste control procedures apply both when defining contracts with customers (the 'type approval' phase) and upon accepting deliveries to the plant.
    The compliance of the quality of the incoming waste with the corresponding approval is checked by means of visual and analytical inspections, carried out instantly, periodically and on a 'spot' basis, including collection of waste samples.
    After checking, the waste is sent for the treatments defined in the approval phase.

Share this