Disinfection by Ultraviolet Light
|Bacillus subtilis (spore)||12.0|
|Hepatitis A virus||11.0|
|Infectious pancreatic necrosis||60.0|
Fig. 4 - E.coli (Waterborne indicator Pathogen) DOSE = 5.4 mJ/cm2
|Dose mJ/cm2||Reduction in number of live microorganisms|
- LIQUIDS: water, syrups, emulsions, brines.
- SURFACES: packaging, conveyors, food, working surfaces.
- GASES/AIR: food preparation, clean rooms, air conditioning.
- OXIDATION: TOC reduction, ozone destruction, chlorine removal.
- CATALYSIS: pesticide removal, effluent treatment, ground Recovery.
- DEODORISATION: sewage and industrial emissions.
MEDIUM AND HIGH PRESSURE ARC TUBES
Power ratings are from 0.4kW to 7.0kW with a maximum treatment capacity of 600 m3/hour with a single lamp.
The high energy output is equally effective on both hot and cold fluids.
The broad spectrum output performs more efficiently than low pressure lamps on flows > 13 m3/hour. Conversion of power input to biocidal output is > 15%.
Useful arc tube life between 4000 - 8000 hours depending on operating conditions.
Full spectrum output 185 - 480 nm available for photochemical reactions.
LOW PRESSURE LAMPS
Ideal for low flow situations with power ratings from 15w to 200w.
Single wavelength output at 254 nm.
Conversion to UV-C typically 30% - 35%.
120 - 200 watt lamps unaffected by water temperatures.
The disinfection process involves the exposure of fluids with microbiological contamination to a UV energy source which is mounted centrally in an irradiation chamber.
Lenntech have always believed that correct chamber design is a significant part of effective disinfection and to this end computer modeling is used to establish turbulent flow, which ensures good mixing and balanced exposure at high and low flows and residence time characteristics.
Lenntech UV Systems design equipments so that the dose is AT THE WALL, AT THE END OF LAMP LIFE. This protects the process from possible inadequate treatment which may occur through short circuiting when average and cumulative doses are is used.
High quality internal finishing avoids shadowing and other bacterial traps.
Chambers have integrally fabricated sample ports, drain and air vents as standard.
The inlet and outlet orientation, size and end termination are to customers specification to aid installation.
SINGLE ARC TUBE CONFIGURATION
Single arc tube configuration greatly enhances performance. One high intensity lamp is capable of disinfecting up to 600m3/hour. UV intensity monitoring is positive, simple, effective and proven.
Multi-tube designs utilizing quantities of low pressure lamps housed in one chamber present both hydraulic and mechanical problems. Maintenance is time consuming and expensive. Baffles are required to introduce turbulence and through the shadowing effect of these it is possible for untreated water to pass through the chamber shielded from the monitor.
UV INTENSITY MONITORING
Willand intensity monitors respond to UV-C. The monitor is the customer's safeguard the unit is operating at efficient output. When low UV-C output threshold is reached an alarm is initiated. Monitor output can be linked to BEM or PLC units to ensure optimum plant operation.
To ensure customers are supplied with the correct unit for the intended application we recommend they contact Lenntech UV to arrange an appointment with a trained Lenntech consultant.
Information necessary to correctly size a Lenntech unit includes, but is not limited to:
1. Peak flow (liters per second or gallons per minute). 2. Fluid sample for free transmission test.
3. Microbiological challenge.
4. Required standard after UV treatment.
All information supplied is in the strictest confidence.