OUR FREQUENTLY ASKED QUESTIONS

UV disinfection is a physical, non-intrusive method of ensuring that, through the partial photo oxidation of an organism’s DNA, it is unable to replicate and with a typical life of only a few minutes, the organism is rendered harmless.

Ultraviolet (UV) is a form of light radiation that is invisible to the human eye and inhabits the electromagnetic spectrum between X-rays and visible light. There are three ranges of UV radiation - UVA, UVB, and UVC as well as Vacuum UV. All types of UV have the potential to damage our skin, but to varying degrees.

The most dangerous type of UV radiation is UVC which exist between 200 and 280nm and the capability to artificially generate light across this range allows the widespread adoption of UV as an environmentally friendly, chemical-free, and highly effective way to disinfect water against pathogenic bacteria, viruses and protozoa.

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UV-C light inactivates microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions and in its simplest terms the effectiveness of UV disinfection depends on the length of time a microorganism is exposed to UV radiation and the intensity of that radiation.

UV Transmissivity (or UVT or Transmittance or Transmission whichever your preference) refers to the percentage of light, at a wavelength of 254nm, absorbed by a water sample across a fixed distance between the light source and the sensor. UVT measurement is affected by the organics, colloidal solids, and suspended particles in a water sample that absorb and scatter the UV light, preventing it reaching the sensor. UVT is defined as the reduction in light intensity after it is passed through a water sample, expressed as a percentage:

uvt2UVT3

How is UVT measured?

The intensity (IM) of UV light at the wavelength of 254nm (UV254), passed through a 1cm wide water sample is compared to the intensity (IO) being measured across air or pure water over the same distance. This provides a measure of the UV absorbance of the water to be treated and hence is an important factor in the design and control of a UV disinfection system.

Even a small change in UVT can have a significant effect on system size, and hence the cost, of a UV System. It is worth considering as well that the UVT at a particular site may vary over time and so as part of any design process it is worth a protracted period of UVT monitoring which will allow for a more accurate system sizing. Long term monitoring will also give an indication of the amplitude and frequency of fluctuations in UVT which can affect UV System control and hence allow a more accurate assessment of operating costs. 

254nm is often quoted as an efficient wavelength for disinfection because Low Pressure Mercury Lamps are able to emit a monochromatic wavelength of UV light at 254nm. And in terms of efficiency it is at least better than the polychromatic Medium Pressure mercury lamp alternative.

UVC LEDs can be manufacture to emit a variety of wavelengths and so the choice of LEDs can be tailored to suit a particular application.

For disinfection purposes the Typhon system uses 275nm LEDs which is very close to the peak for DNA Absorbance for common pathogens such as Cryptosporidium and EColi so delivers a very efficient disinfection process.

The Typhon UV LED system is validated to the USEPA UVGDM protocol which allows the UV Dose to be tailored to suit any required log kill of any known determinant.

Additionally, the Typhon system offers the advantage that UVLEDs can be selected which will deliver the most effective wavelength to suit a particular microorganism.

That means that the required log kill for Adenovirus can be achieved at around 60% of the dose which a mercury lamp system would need to achieve the same performance.

Yes, LEDs which emit a wavelength around 292nm deliver a very efficient de-chlorination process.

Additionally the same system can deliver de-chlorination and disinfection at the same time.

Traditionally mercury lamp UV is combined with Hydrogen Peroxide.

However this process is very inefficient and required a lot of power to generate Hydroxyl Radicals.

Typhon combine 292nm UVLED light with Sodium Hypochlorite which is a common chemical used on many water treatment plants. 292nm is the peak for chlorine absorbance allowing Hydroxyl Radicals to be generated very efficiently

UVLEDs deliver full disinfection in 100milliseconds from start-up so there is no delay is having fully disinfected water available when needed and the system can be switched on and off as often as the process required with no detriment to performance.

LEDs can be switched ON and OFF as often as required with no detriment to performance which can be particularly useful for sites with intermittent flow patterns.

Intermittent flow applications, where a pump might switch flows from zero to max several times during the day can be a real challenge for mercury lamp UV systems for 2 reasons:

  1. It takes some minutes from start-up for the lamps to warm up to deliver the required UV Dose and so the water must be either held back during warm-up or discharged to waste until the system is ready.
  2. Regular restarting of mercury UV lamps reduce the achievable lamp life and compromises disinfection performance.

Yes. Typically UVLEDs can be reduced in power to 30% of their nominal full power output and those adjustments, either up or down, will happen instantly.

However, UVLEDS can be switched ON/OFF instantly and multiple times with no detriment to LED life which offers another interesting way to conserve power while at the same time conserving LED life.

Rather than simply turning down the LED power, The Typhon system can dynamically switch LEDs OFF and ON depending on when they are needed to meet the UV Dose.

In terms of dose control the UV LED systems requires exactly the same inputs as a mercury lamp system with Flow rate and UV Transmissivity being critical parts of the UV Dose calculation.

However, beyond that the UV LED system requires very little supporting infrastructure:

The Typhon system does not have a separate control panel so power and comms connections are directly to the reactor enclosure.

The Typhon system contains no mercury so there is no need for a glass/mercury capture system downstream of the UV System.

Additionally, because of the inlet configuration there is no need for additional straight lengths of pipework upstream of the UV System, all of which contributes to minimising the system footprint.

The Typhon UV LED system emits no heat through the quartz into the water and so removes the potential for scaling completely.

Scaling is caused by operating in hard water areas. Mercury UV lamp emits a lot of heat which causes insoluble calcium carbonate to form a coating on the surface of the quartz sleeves around the lamps preventing the UV light from getting out into the water.

Wiping systems may remove particles that might settle on the quartz sleeves but they have little effect on the chemically induced scaling which requires the reactor to be periodically stripped down to manually clean the quartz.

UV LEDs do not contain mercury.

Traditional Mercury UV lamps contain somewhere between 20 and 200mg of mercury and a portion of that is vapourised during lamp operation.

If a lamp is then broken during operation the broken shards of quartz as well as the mercury can be released into supply.

The Typhon UV LED system contains no mercury at all, delivering an environmentally friendly disinfection solution.

The Minamata Convention on Mercury  is a global treaty to protect human health and the environment from the adverse effects of mercury. 

The convention is symbolically named after the Japanese city of Minamata which experienced a severe, decades-long incidence of mercury poisoning after industrial wastewater from a chemical factory was discharged into Minamata Bay. The wastewater contained methylmercury, which accumulated in fish and shellfish in the bay. Local people who consumed the seafood became very sick, and many died or were left severely disabled.

MMHThe Minamata Convention provides controls on the manufacture, import and export of a wide range of products containing mercury, with the intention for them to be prohibited by 2020 except where countries have requested an exemption for an initial 5-year period.

Why Typhon’s UV LED Water Treatment?

An optimally energy-efficient configuration of UV LEDs in a water treatment system,
will be first to compete with Hg UV, and will retain its advantage as UV LED performance improves.

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