RAINWATER TREATMENT PLANT - Case History

RAINWATER TREATMENT PLANT

Scope: the rainwater ?has to be treated?before being discharged into the sea or sewer, in order to meet the environmental law requirements.

Case History: Rolling Mill Complex

Yard surface for the plant dimensioning:?60.000 m2

Total volume of rain to be collected: 300 m3 (first 5 mm of rain)

Main activities on the yard: billet and rebars stock area , transit of vehicles.

Main pollutants: sand, dust, hydrocarbons and oils.

Water Treatment Scheme:

- SETTLING/ DEOLING in underground concrete tanks

- FILTRATION in pressure SAND FILTER?and CARBON FILTER inside the building

?Fig. 1 – Sand filter and carbon filter?

Advantages/ Distinctive features

·????????No impact on activities of the yard

·????????Full automatic control with the use of rain sensor to manage the plant on the base of the real atmosferic conditions (first rain treated, second rain directly sent to the sea)

·????????Treatment of rain water (collected in a underground tank) at low flowrates (submergible pump 7m3/h). By this way the sand and carbon filters have a small size, with low investment costs, while complying with law requirements (the plant must be available with the full capacity after 48 hours of dry weather conditions).

·????????The partial filling of the storage tank is managed by evaluating the waiting time before the deliver ?to filtration, complying with the law timing and respecting the environmental requirements (stagnation of water for long time is avoided).

·????????The chemical analysis of water discharged into the sea meet the law limits (Italian limits D.Lgs. 152/2006)