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.