puricarexfiles: ULTRAVIOLET DISINFECTION SYSTEMS - Cryptosporidium and Giardia are parasitic. These organisms are in a dormant phase when in water but when they enter a host they release colonies and begin to breed, ultimately causing severe diarrhea and dehydration over a prolonged period of time. Do a bit of research and that you oversize your UV in order to ensure a high UV dose being delivered to your water supply.

Utraviolet

Disinfection Systems

Questions & Answers

Part 2 - Will a UV system kill all microorganisms in my water?

Question: Will a UV system kill all microorganisms in my water?

Answer: All Sterilight systems are rated for a 4-log inactivation of bacteria, viruses and protozoan cysts under specific conditions. This rating is at a specific flow rate, and water quality.

It is a good idea to have your water microbiologically tested prior to installing a UV system.

We do suggest that if your water has bacteria counts in excess of 1000 CFU/10 mL that you do a bit of research with regards to what could be causing such high bacteria counts and that you oversize your UV in order to ensure a high UV dose being delivered to your water supply.

Question: Is UV effective against E. coli?

Answer: Yes, E. coli requires a UV dose of between 6 -10 mJ/cm² to achieve a 4-log inactivation. This is well within the capabilities of Sterilight UV systems.

Question: Does UV inactivate Cryptosporidium (Beaver fever) and Giardia?

Answer: Cryptosporidium and Giardia are what is called a protozoan cyst. Protozoa can be described as microscopic, single celled microorganisms which live in water and are quite a bit larger in comparison to other microbes.

The majority of protozoan cysts are parasitic. Both Cryptosporidium and Giardia are parasitic.

These organisms are in a dormant phase when in water but when they enter a host (being any kind of mammal) they release colonies and begin to breed, ultimately causing severe diarrhea and dehydration over a prolonged period of time.

Cryptosporidium and Giardia were not microorganisms of concern until approximately 10 years ago when Milwaukee was hit with a waterborne disease epidemic. Milwaukee drinking water is surface water, which had become contaminated with high concentrations of Cryptosporidium at the time.

Over 100,000 people came down with Cryptosporidiosis and over 400 people died.

The USEPA recognized that they needed to consider these organisms and include them within their drinking water guidelines.

Testing was done and it was found that chlorine was NOT effective against either of the protozoa. Testing was then conducted using UV technology with initial failure due to improper test procedures.

Ultimately it was proven that UV is in fact very effective against Cryptosporidium and Giardia.

The dose levels required to inactivate these cysts are actually quite low; less than 10 mJ/cm² for 99.9% reduction of both Cryptosporidium parvum and Giardia lamblia.

Question: How do I clean the quartz sleeve?

Answer: If the quartz becomes stained, remove the sleeve from the reactor chamber and clean the OUTSIDE with a commercially available scale remover, such as Lime-Away or CLR.

If the inside of the quartz sleeve does become wet, ensure that it is thoroughly dried before putting the Sterilight system back together.

Question: My lamp is still glowing blue; do I still need to replace it?

Answer: The UV light that is inactivating microorganisms in water is non-visible light, therefore the blue light that you see coming off a UV lamp is not what's doing the work.

A UV lamp can be described as a low pressure mercury vapor lamp, which means it fires via mercury vapor. Over the course of a year that mercury is being used up resulting in a slight decrease of UV intensity.

At the end of one year a Sterilight UV lamp has decreased in it's intensity by approximately 20%. We strongly recommend that UV lamps be changed on an annual basis.

Question: What is recommended maintenance for a UV System?

Answer: Sterilight UV systems require the lamp to be changed on an annual basis (provide they are not installed in a seasonal home).

It is suggested that the quartz sleeve be cleaned during the lamp change provided the home is supplied with high quality water (no iron, hardness etc.) otherwise the sleeve should be maintained on a regular basis.

Please NOTE: If the Sterilight system you have is monitored (ie. Has a sensor) you must ensure that you clean the sensor eye as well as the quartz sleeve.

All new lamps come with a pair of o-rings. Please replace existing o-rings with the new ones.

Question: What does "log inactivation" mean?

Answers: Log inactivation is the inactivation of microorganisms on a logarithmic scale. Microorganisms must be considered on a logarithmic scale due to their high numbers.

Question: Will a UV system restrict my water pressure?

Answer: No, Sterilight systems are designed with inlet/outlet ports correctly sized for the specific application. As an example, the 8 USGPM system comes with 3/4" ports. The typical pressure drop on this system would be 2-3 psi.

Question: I have color in my water causing a low UVT, how do I remove it?

Answer: If you have high color in your water it is most likely a concentration of tannins.

High tannin levels are found in most surface water supplies and some groundwater or simply in waters where large quantities of vegetation have decayed.

Unfortunately tannins cannot simply be removed from water by a physical means of filtration.

Tannins can be described as a colloidal suspension as it carries a negative charge and therefore will not simply fall out of solution like turbidity does.

Tannins are water soluble, organic compounds formed in the decomposition of organics. It can cause a slight yellowish color to the water and will rapidly decrease the level of UVT in your water as the tannin level increases.

The most efficient way to remove tannins from drinking water is by way of an anion exchange system.

Hardness is removed from water via a cation exchange system or softener, as the hardness compounds need to be exchanged with sodium ions in order for the hardness to be removed.

Tannin removal systems work the same way but with a slightly different resin than a softener.

Softeners exchange cations for cations (positively charged ions, like calcium and magnesium in exchange for sodium ions) and tannin removal systems exchange anions for anions (negatively charged ions like tannins in exchange for chloride ions).

Question: What is UVT?

Answer: UV transmittance at 254 nm (which is the wavelength of light that UV lamps operate at) is a measure of the fraction of incident light transmitted through the water column.

The UV transmittance is the ratio of the light entering the water to that exiting the water. The UVT is usually reported for a pathlength of 1 cm. As UV absorbance increases, the UV transmittance decreases (US EPA UVDGM 2003).

UVT is measured using a spectrophotometer. High levels of color &/or tannins will cause a decrease in the UVT level. If the water cannot transmit the UV light, than the UV cannot disinfect efficiently.

Click here for Part 1- Utraviolet Disinfection Systems

What is UV light?

http://puricare.blogspot.com/2017/05/ultraviolet-disinfection-systems-uv.html

Click here for Part 3 – Utraviolet Disinfection Systems

Does my water require pretreatment before my UV?

http://puricare.blogspot.com/2016/04/utraviolet-disinfection-systems.html

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