ULTRAVIOLET WATER DISINFECTION
ULTRAVIOLET
Lights
UItraviolet rays with wavelengths shorter than 300 nm are extremely effective in killing microorganisms. The most effective sterilizing range for UV is within the C bandwidth (UV-C). This range is called the germicidal bandwidth. UV-C has been used in hospitals for decades to sterilize surgical instruments, water, and the air in operating rooms. Many food and drug companies use germicidal lamps to disinfect various types of products and their containers.
DESTROY
Microorganisms

All living organisms contain DNA (deoxyribonucleic acid). DNA provides the mechanism for all functions . needed to sustain life. The UV light from 200 to 300 nm is easy to be absorbed by the cells,and the 253.7 nm has the strongest disinfection ability. The UV light penetrates the outer cell membranes of microorganisms, passes through the cell body, reaches the DNA and permanently alters the genetic material. The microorganisms are thereby destroyed in a non-chemical manner.

Ultraviolet disinfection is a purely physical process. Micro-organisms such as bacteria, viruses, yeast, etc. that are exposed to the effective UV-C radiation are inactivated within seconds. It does not add anything to the water, such as undesirable color, odor, taste or flavor, nor does it generate harmful byproducts. It is fast, efficient, effective, economical and environmentally friendly.

Dosage is the product of Intensity with Contact Time, Intensity*Time = micro Watt/cm²* time = microwatt-seconds per square centimeter (µW-s/cm²). Note: 1000 µW-s/cm² = 1 mJ/cm² ( milliJoule/cm²)
The following are incident energies of germicidal ultraviolet radiation at 254 nanometers necessary to inhibit colony formation in microorganisms (90%) and for complete (99.9%) destruction: Energy dosage of Ultraviolet radiation in µW/cm2.
Microorganisms µW/cm2, 90% Destruction µW/cm2, 99.9% Destruction
Bacteria Bacillus anthracis - Anthrax 4,520 8,700
Bacillus anthracis spores - Anthrax spores 24,320 46,200
Bacillus magaterium sp. (spores) 2,730 5,200
Bacillus magaterium sp. (veg.) 1,300 2,500
Bacillus paratyphusus 3,200 6,100
Bacillus subtilis spores 11,600 22,000
Bacillus subtilis 5,800 11,000
Clostridium tetani 3,370 6,510
Corynebacterium diphtheriae 2,140 4,100
Ebertelia typhosa 3,000 6,600
Escherichia coli 3,150 6,000
Leptospiracanicola - infectious Jaundice 6,050 12,300
Microccocus candidus 1,000 15,400
Microccocus sphaeroides 6,200 10,000
Mycobacterium tuberculosis 4,400 8,000
Neisseria catarrhalis 3,000 6,600
Phytomonas tumefaciens 5,500 10,500
Proteus vulgaris 3,500 6,600
Pseudomonas aeruginosa 4,000 7,600
Pseudomonas fluorescens 3,200 6,100
Salmonella enteritidis 2,150 4,100
Salmonela paratyphi - Enteric fever 8,000 15,200
Salmonella typhosa - Typhoid fever 19,700 26,400
Salmonella typhimurium 2,420 6,160
Sarcina lutea 2,200 4,200
Serratia marcescens 1,700 3,400
Shigella dyseteriae - Dysentery 1,680 3,400
Shigella flexneri - Dysentery 4,400 6,160
Shigella paradysenteriae 1,840 5,720
Spirillum rubrum 2,600 6,600
Staphylococcus albus 2,160 5,500
Staphylococcus aerius 6,150 8,800
Staphylococcus hemolyticus 2,000 3,800
Staphylococcus lactis 6,150 8,800
Streptococcus viridans 2,000 3,800
Vibrio comma - Cholera 3,375 6,500
Molds Aspergillius flavus 4,520 8,700
Aspergillius glaucus 24,320 46,200
Aspergillius niger 2,730 5,200
Mucor racemosus A 1,300 2,500
Mucor racemosus B 3,200 6,100
Oospora lactis 11,600 22,000
Penicillium expansum 5,800 11,000
Penicillium roqueforti 3,370 6,510
Penicillium digitatum 2,140 4,100
Rhisopus nigricans 3,000 6,600
Protozoa Chlorella Vulgaris 6,050 12,300
Nematode Eggs 1,000 15,400
Paramecium 6,200 10,000
Virus Bacteriopfage - E. Coli 3,000 6,600
Infectious Hepatitis 5,500 10,500
Influenza 3,500 6,600
Poliovirus - Poliomyelitis 4,000 7,600
Tobacco mosaic 3,200 6,100
Yeast Brewers yeast 8,000 15,200
Common yeast cake 19,700 26,400
Saccharomyces carevisiae 2,420 6,160
Saccharomyces ellipsoideus 2,200 4,200
Saccharomyces spores 1,700 3,400

As a general guideline, the following are some typical UV transmission rates (UVT) :

  • City water supplies : 85-98%
  • Ground water (wells) : 90-95%
  • Surface waters (lakes, rivers, etc) : 70-90%
  • Other liquids : 1-99%
  • De-ionized or Reverse Osmosis water : 95 -98%
UVT(%) 70 75 80 85 90 94 95
Factor 0.42 0.46 0.52 0.63 0.78 0.98 Aqualight® Standard

Find adjusted flow rate for UVT levels other than 95% :

  • Select the "Factor" from the chart for UVT adjustment
  • Divide 30mJ/cm2 by the "Factor" numbers for an adjusted dose
  • From the systems graph of flow rates vs. UV dose, select the adjusted dose on the X-axis and follow the line to the point of intersection on the system model curve. Follow a horizontal line across to the line Y-axis to find the "Adjusted" flow rate

Find adjusted dosage :

  • Select the "Factor" from chart for an UVT adjustment
  • Select the flow rate on the Y-axis and follow a horizontal line to the system model curve and follow that line down to a dose number(mJ/cm2), then multiply the dose number by the selected "Factor" numbers to get an adjusted Dose

Find appropriate system :

  • Select the "Factor" from chart for an UVT adjustment
  • Divide the manufacturer's dose standard (or NSF standard) by the selected factor numbers for an adjusted dose
  • Select the follow rate on your request from the Y-axis and the adjusted dose on the X-axis to get your system model (recommend a larger system if the selected point between two curves).
ADVANTAGES
  • No chemicals added
  • No environmental problems
  • No by-products that might endanger health
  • No reaction tanks or secondary pumps
  • Micro-organisms inactivated within seconds
  • Minimum operating costs
  • Maximum operating safety
  • Modular system for adaptability
  • Water retains its natural flavor and smell