Rain water sector
STA rain water treatment plants, Series S.MET 1p, are designed and manufactured according to the resolutions imposed by the different regional regulations, as well as by the national regulations in force (Legislative decree 152/2006) and provision by the Managers of the Integrated water services.
Rain waters are waters corresponding in the first part of the rainfall, to a 5 mm rainfall, evenly distributed on the whole draining surface covered by the rain water draining network, consisting of one or more rainfalls, within a different time span or one after the other within 48, 72 or 96 hours from a similar previous rainfall event, according to the regional regulations in force.
Rainfall water, collected from the draining surfaces, risk of being contaminated by the presence of sands and mineral oil from the parking or passage of any transportation means.
The water treatment is therefore based on the following operating steps:
- collection of the rainfall water volumes
- separation of the first rainfall water from the later rainfall
- separation of setteable solids and mineral oils
- separated disposal of the two wastes
Run-off rain waters from the draining surfaces are collected in a dam, sized according to collected first rainfall volume.
The first rainfall waters are separated from later rainfall waters through a back-flow valve fitted with a floating control, clogging the inlet to the treatment plant when the set level is reached. Within the treatment vessel, within the relative calm created, through the back-flow valve operation, sand is removed (seattable solid decanting and at the same time oil) which profiting from the oil lower weight than water, leads to the perfect mineral oil separation through flotation.
A peculiar device traps polluting substances inside the rainfall dams, thus leading to a good waste quality, compliant with the limits forecast by the regulations in force in terms of specific parameters (mineral oils and seattable solids). Accumulated foots are periodically disposed of through self cleaning.
Once the time interval set by the regulation in force elapses, collection is provided to the final receptor (generally sewage, unless differently imposed) through a pumping system, conveying treated waters at a controlled capacity.