About UV technology


UV technology has a long history of over 100 years and has since then experienced a thorough utilization of the technology’s potential. Today, UV disinfection is recognized as an effective method in a wide range of water qualities and applications. Improved technological and design configurations have made UV a viable OPEX and CAPEX solution for disinfection processes, as well as in more advanced applications such as Advanced Oxidation Processes (AOP).

The sustainable method is based on the natural disinfection action of the sun’s rays. UV systems produce the same ultraviolet germicidal rays through its UV lamps, just thousands of times stronger. No bacteria, viruses, molds, or spores are able to withstand this water treatment path, making ultraviolet technology a globally accepted solution for water disinfection.

The use of UV technology effectively ensures that the water quality, both physical and chemical, remains identical before and after the treatment. Additionally, the reaction time between the UV irradiation and the organism to be inactivated is very short and does not create any by-products at all. These are some of the advantages that makes UV technology systems the preferred solution in a wide range of water treatment applications.

The radiation dose or fluence is a design parameter for the disinfection effect of the UV irradiation. The necessary dose to achieve a given inactivation depends on the organism to be killed. The measurement is expressed in mWs/cm² and/or mJ/cm².

UV Transmission is the measure of the UV light’s ability to pass through 1 cm of liquid. When light irradiates the water, the water absorbs a part of the radiation, resulting in a decrease in light intensity from the lamp. The design of ULTRAAQUA UV systems takes this into account, being easy to install, maintain and thoroughly cost-optimized. Get an in-depth view of how uv systems work here.

Ultraviolet lamp technology

UV Lamps & Wavelength

UV is a spectrum of light that is just below the visible range to the human eye. The UV-C spectrum (185 – 280 nm) is known as the germicidal spectrum because it is the region that contains the peak germicidal wavelength (260 nm). The UV units for water treatment consist of a specialized low-pressure high output lamp with Mercury indium amalgam filling that produces ultraviolet radiation at 254 nm – very close to the optimum at 260 nm. Compared to the low-pressure lamps, the medium pressure lamps are less efficient in utilizing usable germicidal wavelengths. Medium pressure lamps generally only convert up to 10% of their input watts into usable UV-C watts, whilst amalgam low-pressure lamps can be up to 40% efficient. There has been a drastic rise in market share for “low pressure-high intensity” amalgam lamps in the past few years. This has primarily been driven by the need for higher electrically efficient lamps (thus lower electrical operating costs) combined with the growing awareness in using “green” technologies to reduce carbon footprint.


UV systems consists of a control cabinet and a UV reactor. While there are many UV systems in the industry today, the quality of its essential internal parts determines its performance. ULTRAAQUA UV systems use the highest-grade materials and components available on the market.



• Monochromatic spectrum
• Power density app. 0,5-5,5 W/cm
• Power levels 0-1000 W
• Efficiency 32-40%
• Lamp lifetime 16.000 H
• Lamp surface temperatures 40-130 °C



• Polychromatic spectrum
• Power density app. 100-500 W/cm
• Power levels 0.5 – 50 kW
• Efficiency 7-15%
• Lamp lifetime 9.000 H
• Lamp surface temperatures 600-800°C



The ULTRATHERM™ quartz sleeves are made from the highest purity quartz available. If they are not scratched or fouled, they have an unlimited lifetime. This guarantees excellent UV ray transmission and effective disinfection. It is essential to keep the quartz sleeves clean as any fouling can trap the UV light, resulting in a negative impact on the entire disinfection process. The suggested replacement interval is <24,000 hours.



ULTRATOUCH™ control cabinets are designed for installation in industrial environments. The design reflects the “what you need to know when you need to know it” philosophy. With multiple features and enclosure material options, they can be designed specifically for a variety of applications and climates. All internal components are from established European suppliers, delivering smooth and energy-efficient operations.

Frequently Asked Questions

Your guide to UV technology

Since the technology was invented over 100 years ago, the use of UV technology has experienced rapid growth and continuous development to achieve maximum efficiency in various water treatment applications. Today, the potential and advantages of the technology are hard to ignore for the many available water treatment applications. In the guide below, you can find answers regarding its efficiency, functionality, benefits and more.

Why is UV disinfection a preferred water disinfection solution?

In most cases, ultraviolet disinfection is the last step of the water treatment process, destroying the tiniest particles that cannot be filtered out by existing filters. UV disinfection is the only solution that does not change any properties such as pH and temperature – which is essential for applications such as aqua life and ultra-pure water.

Ultraviolet disinfection is extremely effective in destroying microorganisms since no known bacteria or viruses are resilient to UV light. Furthermore, the technology today is optimized to a point where UV systems are usually the best OPEX and CAPEX wise due to energy use, footprint, and high level of automation. It also requires the shortest contact time without the need for additional supportive infrastructure.

Even though some of the alternative solutions possess sections of UV technology advantages, only UV disinfection delivers them all at once.

What are the most common UV applications for water treatment?

Besides standard disinfection, the other most common UV applications for water treatment are:

  • De-chlorination: usually when the water in the inlet point has been pre-treated with chlorine and the further processes cannot tolerate it and its by-products. Commonly found in high-purity water applications like injection water for food and beverage, pharmaceuticals, and microelectronics industries. It is also extremely effective for swimming pool water.
  • De-ozonation: ozone can sometimes be used to clean up the entire piping systems and places that cannot be accessed by maintenance teams. However, ozone is highly chemically reactive and needs to be eliminated, in order not to harm the end product in high-purity water environments or aquaculture species.
  • TOC reduction: in the drinking water industry, TOC is directly associated with THMs and HAAs formation when chlorine is used. By destroying TOC, the formation of dangerous microorganisms is reduced significantly. It is also very common in pharmaceuticals and microelectronics industries.
  • AOP: used in applications where the microorganisms are complex and cannot be destroyed by typical UV light, or where high purity water is required. The AOP process consists of UV and hydrogen peroxide, ozone, or both.

Can UV light kill COVID-19 virus?

UV light has been proven to effectively eliminate the Covid-19 virus. However, based on the latest research, the covid-19 virus cannot survive the whole water treatment path. Because of this, there is no actual need to treat drinking water from covid-19.

How often do I need to replace UV lamps?

UV lamps should be replaced before reaching the expected lamp lifetime. For Low-Pressure – High Output ULTRATHERM™ UV lamps this is 16.000 hours, while Medium-Pressure High Intensity ULTRATHERM™ UV lamps are set to 9.000 hours.

How do I select the right UV system?

Some of the most important factors in determining the right UV system are knowing the location, application, flow rate, UV transmission, and targeted bacteria. ULTRAAQUA is able to assist in assessing all of the factors to ensure that the right UV system is chosen. By sending a sample to our headquarters in Denmark, we can help with assessing the bacteria to be targeted in our state-of-the-art laboratory.

By providing the desired log reduction and/or pre-filtration we can help find the perfect solution for your needs. The more information engineers have available, the better product fit and pricing can be offered to the requesting party.

Read more about using UV Dose to find the right UV system here.

What are the operation and maintenance costs of a UV system?

Operation costs are based on the power supply, which can vary greatly depending on the type of the UV system.

The UV maintenance costs are the lowest possible compared to its alternatives. It is also safe without involving dangerous chemicals. Depending on the application, the inspection should be done annually, with lamp re-placement up to two years (medium pressure more often), and quartz sleeves up to four years.

What is UV Transmittance and why is it important?

UV Transmittance is essential to know as it helps identify how clean the water is, resulting in better conditions to ensure proper water disinfection.

By knowing the UVT of the water to be disinfected, it becomes possible to properly size the UV system for optimal disinfection.

Read more about UV Transmittance here.

Can I install a UV system outside?

It is possible to install a UV system outside, however, the control cabinet should be covered from direct sunlight or rainfall.

Can UV reduce Total Organic Carbon (TOC) in water?

TOC UV Systems uses UV lamps that emit light at 185nm wavelength. The light energy promotes the formation of OH-radicals from the photolysis of water. The OH-radicals react with the organic matter in the water leading to the oxidation into CO2 (carbon dioxide) and H2O (water), effectively resulting in the removal of TOC.

Read more here about TOC reduction here.

How long does it take for UV to kill bacteria in water?

The time required for UV systems to kill bacteria in water varies significantly, based on factors such as the targeted bacteria, the intensity of the lamps, as well as the UV transmittance of the water. All relevant factors are naturally considered when sizing the optimal UV system for your requirements.

Does UV treatment require pre-filtration?

Even though UV disinfection provides extremely effective protection against pathogenic microorganisms, pre-filtration is often a neccesity before the UV treatment process.

Pre-filtration is used across numerous applications to filter out larger particles and solids that could create a shadowing effect. If a shadowing effect occurs, the potentially harmful microorganisms might not be able to receive the necessary amount of UVC light.

The amount of required pre-treatment varies a lot, but ultimately depends on the UV rays being capable of “reaching” all pathogens in the flow-through water. The better-pretreated water is, the less UV light is needed and therefore more energy savings. For low UVT environments, ULTRAAQUA offers multiple series that are optimized for energy-efficiency.

What is the best UV reactor and control cabinet material?

The best material depends on the source of water to be treated. If the environment is corrosive due to saline or air humidity, it can be a challenging setting for the commonly used UV system materials in stainless steel.

Based on 25 years of experience with seawater disinfection in warm and cold-water environments, ULTRAAQUA offers UV-stabilized polypropylene (PP) systems, which are resistant to warm seawater applications due to their non-corrosive construction.

For other environments such as cold seawater and freshwater applications, electropolished steel is a possibility, which provides up to 30% extra energy efficiency due to internal reflection.

For control cabinets, Glass Fiber Reinforced Plastic (GFRP) with passive or active cooling is a possibility, which causes the inside of the cabinets to be protected from any external factors.

How to choose the most suitable lamp technology?

Medium-Pressure lamps consume more electrical energy per unit of germicidal light output compared to Low-Pressure lamps. Additionally, MP lamps generally only convert up to 15% of their input watts into usable UV-C light watts, while LP lamps can be up to 40% more efficient.

However, UV systems based on MP lamp technology have the advantage when it comes to high-flow applications where a small footprint is essential and high-power densities are required.

The decision of what lamp technology to use should be based on operational and design advantages, taking the lamp characteristics and especially the site-specific conditions into consideration.

Click here to learn how to choose the right UV lamps.

What UV intensity is needed to kill bacteria and viruses?

The UV intensity requirement varies a lot, based on industry and applications. The averages are as follows:

  • Coliform bacteria, legionella, fecal bacteria, streptococci, nematodes (eelworms) and yeasts, etc. – 3 – 40 (mJ/cm²)
  • Pathogenic fungi, such as fusarium, pithium, phytophtora, etc. – 30 – 120 (mJ/cm²)
  • Viruses such as cucumber virus, olpidium, cholera, etc. – 60 – 250 (mJ/cm²)

Within the aquaculture industry, UV doses for common aquaculture diseases include:


  • Aeromonas salmonicida – 5.0 mJ/cm2
  • Aeromonas hydrophila – 5.0 mJ/cm2
  • Flavobacterium psychrophilum – 126 mJ/cm2
  • Vibrio salmonicida – 1.5 mJ/cm2
  • Vibrio anguillarum – 4.0 mJ/cm2
  • Pseudomonas Fluorescens – 11.0 mJ/cm2
  • Renibacterium salmonicida – 20.0 mJ/cm2
  • Bacterial Kidney Disease (BKD) – 60.0 mJ/cm2


  • Infectious Salmon Anemia Virus (ISAV) – 10.0 mJ/cm2
  • Infectious Pancreas Necrosis Virus (IPNV) – 250 mJ/cm2
  • Nodavirus – 200 mJ/cm2
  • Infectious hematopoietic necrosis Virus (IHNV) – 30.0 mJ/cm2
  • Atlantic Salmon Paramyzo Virus – 240.0 mJ/cm2
  • Heart Sceletal Muscle Inflammation (HSMI) – 250.0 mJ/cm2
  • Nervous Necrosis Virus (NNV) – 70.0 mJ/cm2

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