Waste water

Waste water do always need a disinfection process via UV rays to respect law limits. SITA since more then 30 years produces equipments for this application.



The fear for the increasing level of pollution, due both to natural causes and to the uman activity, makes the need of having a pure water more and more important. Waste water, both for the volumes treated and for the direct effect on the environment, plays an important role in the matter of pollution and is a key factor for land conservation.
For this reason and according to the present laws concerning the provisions for the protection of water from pollution SITA has a range of products for the treatment of waste waters.
Differently from the classic UV chambers assigned to the treatment of primary waters, for secondary waters it is necessary to have a different disposition and number of lamps. Such plants find an application in the final part of the treatment process, where the pre-treated and filtered water, rich in bacterial charge, needs to be disinfected.
The problem of secondary waters is not less important than the one of primary waters in fact, the water coming from industrial and/or sewer discharges goes directly into rivers or into the sea with all is bacterial charge and pollutes them and all neighbourhoods.


The widespread treatments of hyper-chlorination show unquestionable problems linked to the production of DBP (Disinfection By Products). Reacting with the nitrogen compounds normally present in the polluted waters, the disinfectants with a chlorine basis give origin to a long series of undesired by-products, with mutagenic–carginogenic features (trihalomethanes, chloramines, and so on).
On the contrary, the ultraviolet radiation is characterized by the irreplaceable advantage of having no danger deriving from overdosing.

Technical Features

The main technical features are the following:

  • Low or medium pressure GERMICIDAL LAMPS, according to the project. In any case all the lamps are characterized by a high ultraviolet emission in C band, with a remarkably pronounced peak on the wave length λ=254nm (maximum resonant absorption by DNA-RNA nucleic acids of the bacterial charge).
  • STAINLESS STEES UV CHAMBER: For this kind of applications the use of AISI 316L stainless steel is recommended
  • RADIATION SENSOR: for the continuous monitoring of the radiation emitted by the UV lamps.
  • TEMPERATURE SENSOR: For the monitoring of the water temperature (in order to prevent over-temperatures in the case of absence of flow)
  • ELECTRICAL PANEL: through which it is possible to turn le germicidal lamps on, and to control instant by instant on the display, the alarm LED, the exchange contacts, the correct working of the system (see detailed technical sheets)
  • QUARTZ SLEEVES CLEANING SYSTEM: The treatment of waste waters generates deposits on the quartz sleeves of lamps, consequently the system can be supplied with a manual or automatic cleaning system (see detailed technical sheet).


For this particular series of equipments does not exist a standard series in fact, considering the great variety of flow-rates and of the chemical-physical characteristics of the waters to be treated, we prefer time by time to size the system for each specific requirement. For this reason our Technical Department is always ready to give the customer the maximum assistance in order to identify the more suitable system for any problem.
The strictly necessary data for the sizing of a UV system for waste water are:

  1. diameter of the piping,
  2. transmittance of the water to the UV-C radiation,
  3. flow-rate to be treated.

Of course, in order to operate a complete evaluation we would need as well the chemical/physical and bacteriological analysis of the water to be treated.