UV-DESINFECTION

         Content

           Introduction

           Technical design of the UV-sterilization devices type „PUV“
 

Introduction

Technical design of the UV-sterilization devices type „PUV“

UV-radiations are energy electromagnetic radiation, which occur in the natural spectrum of the radiation, which is created by the sun. They are in the area of short wave invisible light of 100 - 400 nm.

The physical quantity: 1 nm = 10-9 m. (nm = nanometer = billion meter)

The UV-radiation is divided as follows:

            - UV - A                     315 - 400 nm
            - UV - B                     280 - 315 nm
            - UV - C                     100 - 280 nm

The range of radiation under 200 nm covers ion ozone generating or hard radiation. This range is in general not approved by authorities for the treatment of drinking water and therefore not used in the water treatment.

It was found that the wave range of 254 nm has a very strong performance for disinfection. This is due to the fact, that the absorption spectrum of the DNA (Desoxiribonucleinacid) has its max. value between 260 nm and 280 nm. This is shown in the following graphic.
 

The low pressure mercury vapour lamps which are used for the UV-disinfection have its max. performance out a wave length 254 nm and are similar to the absorption curve of the DNA. The reaction of the UV-radiation is a photochemical reaction of the DNA, Dimeren will be build, mainly at the Thymianbases. Due to this effect bond to the Adeninbases will be blocked, and the cell growth and metabolism is not possible.

So the microorganism will be inactivated and will be neutralized. No by-products will be produced, which could change the water or do will create negative couses of the consumption of the drinking water.

 Following you will find a UV-dose-table of D10 - and D0,1 for the destruction of microorganism. The D10-value shows, which dosage has to be given to an amount of microorganism, to get a reduction of 90%, the D0,1-value shows the dosage for a reduction of 99,9%.

UV-C dose rate at 254 nm for destruction of 90% or 99,9% of different microorganism

 * UV-dosing rate in mWsec/cm for destruction of 90% of microorganism

** UV-dosing rate in mWsec/cm for destruction of 99,9% of microorganism

The artificial production of UV-radiation will be made with low pressure mercury germicidal lamps.

The low pressure mercury vapour lamps consist of one hermetic closed discharge vessel. The gas, which is in the inside is a vacuum sealed against the outside..

A voltage will be generated, which generate an electrical field between the electrodes. Is the accelerated voltage high enough, electrons will leave the electrodes. They will be speeded up in the electrical field. If they crash with the gasatoms they discharge their kinetic energy. This atom or molecule decrease to a lower energetic level or to the basis level. The released energy normally will be emitted in kind of radiations, so called quants.
Due to the energy in the atom, mercury is a very good gas for production of UV-radiation.
In principle 3 types of mercury-lamps are differentiated.
            - low pressure lamps
            - mid pressure lamps
            - high pressure lamps

The used low pressure lamps can only be operated with a lower performance, but they have a much better efficiency of about 45% congored to the mid- or high pressure lamps. Using high- or mid pressure lamps, the operating costs will be higher. Due to this fact, mostly low pressure lamps are used.

Technical design of the UV-sterilization devices type „PUV“

All UV-devices are build cylindrical. The flow cylinder is made from stainless steel (1.4571). Each UV-lamp is protected by one quartzglaspipe, which separates the UV-lamp from the medium. This quartzglaspipe has a UV-C radiation permeability of 98%.

All PUV-systems are designed that at minimum an intensity of radiation of 40 mW sec/cm will be reached under the given max. flow in m³/h.

The UV-lamps are mercury-low pressure lamps and they are designed for a operating time of about 8.000 hours.

Each quartzglaspipe can be removed separately, so that a cleaning and maintenance can be done easily.

UV - System Type PUV 4S

Overview  UV - Disinfektionssystems  Type " PUV

UV - System Type PUV 6S

The systems are equiped with
            - one LED-display per UV-lamp
            - operating hours counter
            - display of operation
            - display for disturbance or alarm
            - pot. contact for remote-alarm

The systems PUV - 1S and PUV - 2S do have a transformer 220V/24V and a high frequency disturbance filter.
All the other systems do have a switch cupboard  with ventilation, main- and single switches.
Feed voltage 220V/380V - 50 Hz.

Type PUV 1S

Type PUV 2S

Options:

- UV-C Intensity Control Measurement and Display can be supplied for all devices   from PUV-4S, for measuring the lamp intensity (about 254 nm).  The display shows the remaining percentage of effectivity and permits conclusions  regarding length of life, pollution of the quartz pipes and water quality.

- Temperature measurement and Display can be supplied for all devices from  PUV-4S to avoid high temperatures during stand-byl and to switch off the device at  set-point.

- Cleaning system for the plants of the type PUV „XL“ for cleaning the  quartz glass pipes manual or automatically.

- Electronic programmable controller for the plants type PUV „XL“, to control the  UV-systems as free programmable PLC

- Vertical arrangement of the UV-lamps, if a horizontal installation is impossible  due to local reasons. Dimensions on design on request.