U.V.
U.V.UV disaffection technology is widely used around the world to ensure safe water free from bacteria without the use of chlorine or other unpleasant chemicals, eliminating the risk of overdosing or imparting bad taste.
CPF ultra violet systems all utilise low pressure mercury vapour discharge lamp to produce ultra violet light at the 254nm wavelength (UVC) which is lethal to micro-organisms. The stainless steel chamber incorporates a high purity quartz sleeve around the lamp. As water passes through the chamber, UVC light penetrates and destroys the cell structure of micro-organisms in the water.
We offer high quality, reliable ultra violet disaffection systems for applications ranging from:
Domestic systems
Commercial systems
Industrial systems
Municipal systems
Waste water treatment system
WATER STERILIZATION WITH UV-C IRRADIATION
WHAT ARE UV-C RAYS?
The small part of electro-magnetic spectrum having wave lengths included between 100 and 400 nm (thousandths of micron) is defined as space of the ultra-violet irradiation. The UV-C are part of the subspace characterized by the wave lengths included between 100 an 280nm. Electro-magnetic waves with different wave length and width induce interactions with the matter of different nature, the UV-C irradiation with 2 = 254nm is particularly interesting thanks to its marked germicidal power.
WHY DO THEY WORK?
The high germicidal power of this wave length must be sought in DNA and in the link of its fundamental components (nucleotids). DNA is a macromolecule present in all living organisms in which all information necessary for life and reproduction reside. The alteration, induced by the UV-C irradiation, of some chemical links present among nucleotids is able to change the information contained and conveyed by DNA, these alterations prevent its normal activity and this irreversibly leads to the cellular death.
HOW MUCH DO THEY WORK?
For being effective in the sterilization, an electro-magnetic wave, besides being of a certain kind (2 = 254nm) it must possess also a minimum value of intensity to be able to ensure a minimum dose to water. The parameters which mostly influence the calculation of the dose are: P=power of the UV-C lamp, T=time of exposure (which depends on the flow-rate and on the dimensional characteristics of the unit), exp(-kx)=transmission factor (depending on the distance of the UV lamp and on the transparency of water), Ct=temperature coefficient of water. A UV sterilizer, if correctly sized, is able to give water a dose sufficient for reducing almost all the commonest micro-organisms present in water.
HOW ARE THE PRODUCED?
In nature the UV-C rays are part of the secondary cosmic irradiation which, interacting with the high strata of the terrestrial atmosphere, generates ozone and with a lower energy, it reaches ground as tanning UV(A+B) irradiation. Artificially UV-C rays are produced with the help of special fluorescent lamps containing mercury fumes, these lamps are made of a very pure quartz (>99.99% SiO2) transparent to the UV-C light which they emit in an almost monochromatic form (>95% of 2=254nm).
WHY ARE THEY CONVENIENT?
Among the several advantages offered by this kind of technology we mention:
environmental treatment (without addition of chemicals, without alteration of taste),
no danger of over-dosing and no alteration of the characteristic of water,
quick action (without any stocking tank) the time is the one of passing through the sterilizer,
compatibility with the other technologies (filtration, softening, etc) for a complete treatment
of water,
cheapness and practicalness thanks to the low consumption of electrical energy and to the little required servicing
COMPARISON BETWEEN SOME DISINFECTION TECHNIQUES
Among the different techniques adopted in the disaffection of waters, the choice of one rather than another, depends fundamentally upon the degree of pollution of water, upon the use that one must make of it, upon the financial engagement requested and upon the possible limits of the employment.
We illustrate a comparison table between the main disinfection techniques commonly used.
PHYSICAL TREATMENT CHEMICAL TREATMENT
UV-C Chlorinisation Ozone
Germicidal effect Good Good Good
Oxidative power No High High
Elimination of algae Yes (high doses) No Yes
Advantages
Unchanged taste
Immediate action
Cheapness
No micro-organism is
resistant
No superior limit of dose
Lasting effect
Unchanged taste
Limits
No lasting effect
Clear water is necessary
It modifies taste
Superior limit of
dose
It modified PH
Time for storage
It is expensive
On the table, the undeniable typical values of a disinfection through UV-C equipment result to be evident, especially in the field of primary waters; in spite of this, very often only the whole of different treatments and equipment can supply a valid and safe final result.
The main advantages offered by ultra-violet sterilizers can be in conclusion summed up as follows:
ECOLOGICAL TREATMENT
Asthe working principle is physical and not chemical, nothing is added to, not taken away from water; in this way there is no formation of any kind of undesired by-products even in the case of overexposures, in the full respect of environment
IT DOES NOT CHANGE THE ORGANOLEPTIC FEATURES
When the water treated is for human consumption this aspect is of primary importance, because the UV-C radiation does not change neither its taste nor its smell
UV-C Dose (254nm) sufficient to eliminate in different percentages (90% - 99% - 99.99%), micro-organisms of various nature:
QUICK ACTION
The times of interaction water-radiation are of few seconds; the disaffection directly takes place only during the passage of water. For this it is necessary to install the UV-C unit always after any other treatment equipment, immediately before the utilization tap, in order to avoid possible successive contaminationĚs.
COMPATIBILITY WITH OTHER TECHNOLOGIES
In order to obtain a complete treatment of water when necessary, it is possible to join a UV-C sterilizer after a softener, a reverse-osmose system with a storage tank, a deironiser or any other treatment equipment.
SIMPLENESS AND CHEAPNESS
The simple and tested construction principles make our units safe and trustable; the low consumption (starting of the lamp = few total watts) and the little maintenance required (annual replacement of the lamp) make them very cheap.
On the other end there is an element which, more than any other; has the power to affect the efficiency of these units: THE TURBIDITY OF WATER.
Such parameters must assume the lowest possible values, so that the irradiation results at the maximum, that is why it is so important to install a filter before any UV-C unit.
With regard to this it is necessary to specify that the dosing values declared are not absolute, but relative to the characteristics of water.
Here are the values regarding some chemical-physical parameters that a water which must be treated with UV sterilizers should have:
- Ideal temperature 20C
- colour absent
- turbidity no
- Fe < 0.3 mg/l
- Mn < 0.05 mg/l
- TDS < 10 mg/l