Safe water technologies: An introduction to UV water disinfection

Water is used everywhere, from agricultural and industrial to residential and healthcare settings and beyond. Whatever the specific application – whether it’s potable water, wastewater, reuse water, or rainwater – safety is paramount.There are many ways to make water safe for use, including various processes for filtration (nano, ultra, and reverse osmosis) and disinfection (chemical and non-chemical). Which process or combination of processes is used depends on various factors, such as the initial water quality, intended end use, and logistical and economic considerations.

In this blog post, we focus on ultraviolet (UV) water disinfection, providing an overview of where it fits into the big picture of water disinfection, how it works, and how it is evolving.

The water disinfection landscape

In general, there are two main categories of water disinfection technology:

1. Chemical technologies, which include chlorine, ozone, and peracetic acid
2. Non-chemical technologies, which include UV disinfection

uv-water-disinfection-benefitsEach technology has a unique set of advantages and disadvantages. For example, chemical disinfection using chlorine is highly reliable and inexpensive, but it also poses safety risks related to the handling of chlorine and the creation of toxic byproducts.

When deciding which technology is best for an application, engineers typically take into consideration a range of factors, including requirements for biocidal efficiency, practicality, reliability, cost, environmental impact, and occupational health and safety.

Harnessing the power of UV light

UV water disinfection harnesses the germicidal power of short-wave UV light – specifically at the 254 nm wavelength – to damage the DNA of cells and viruses. Applying UV light at this specific wavelength to water renders any microorganisms sterile, thereby disinfecting the water.

The first use of UV water disinfection technology was in 1910. Since then, the use of UV systems has grown as the technology has evolved along with scientists’ understanding of how UV light combats waterborne threats.

Compared to chemical disinfection technologies, non-chemical UV disinfection offers several key benefits in terms of safety and efficacy, including:

  • Fast-acting, triggering a reaction almost instantly
  • No disinfection by-products
  • Safe and chemical-free, avoiding the handling and disposal hazards associated with chemicals
  • Environmentally responsible technology
  • Does not alter water chemistry and its constituents, such as pH, taste, odour, colour, etc.
  • Proven and trusted

Different technologies for UV water disinfection

Since that first application, the sophistication and capabilities of UV water disinfection technology have grown exponentially. While manufacturers offer endless options for UV water disinfection systems spanning different makes, models, and specifications, they can all be grouped into two main categories:

  1. Light-in-a-pipe systems. In these systems, pressurized water is exposed to 254 nm UV light as it flows through a quartz tube. Light-in-a-pipe systems are advantageous in that they offer greater control over water conditions within the system, such as preventing exposure to airborne pathogens. However, they can be costlier to operate given increased energy requirements and maintenance costs.
  2. Channel systems. In these systems, non-pressurized water is exposed to 254 nm UV light as it flows through an open channel. Channel systems are often used to disinfect large water streams – especially wastewater streams – as they can offer lower operation and maintenance costs. However, channel systems are also more vulnerable to airborne pathogens and other risks due to their open nature.

As both types of systems have advantages and disadvantages, it’s important for engineers to understand their options and find the best fit for their project requirements.

uv-water-disinfection-benefits

Making water safer with better UV technology

UV systems are already a safe and reliable solution for disinfecting potable water, wastewater, reuse water, and rainwater, and they are only becoming better with continual advances in technology.

Here are a few of the ways in which UV water disinfection technology is becoming smarter and more effective:

  • UV dose consistency. Maintaining a consistent UV dose is important to ensure that all the water flowing through a UV system meets the minimum requirements for safe disinfection. Advances in lamp technology allow lamps to be calibrated to operate at a higher intensity initially and maintain the minimum required lamp intensity until the very end of their lifespan.
  • Real-time monitoring. UV systems typically have sensors to indicate when performance falls below minimum thresholds. However, when sensors are poorly calibrated or the cause of an alarm is not clear, it can be a nuisance for operators. Fortunately, smarter sensors and remote real-time monitoring are continually improving reliability while reducing maintenance requirements.
  • 360-degree coverage. Suspended and dissolved solids in the water can cause shadowing within a UV disinfection system, reducing its efficacy and thus the safety of the water. This challenge is being overcome with smarter system design, such as using dual lamps and reflectors to provide 360-degree UV light coverage that attacks pathogens from all angles.

With some countries actively shifting away from chemical disinfection of water due to health and safety concerns, demand for UV water disinfection is set to grow further. And with smarter technology making UV systems a better choice across diverse applications and industries, understanding UV water disinfection is becoming increasingly important for engineers around the world.

Five considerations for upgrading an existing UV Pure system

Over 18,000 UV Pure systems are operating worldwide – with many providing years or even decades of reliable disinfection performance in potable, wastewater, and reuse applications. Over time, requirements for some sites can change, leading operators to evaluate different disinfection options to cope with higher flow requirements, changing water quality, emerging pathogenic threats or other factors.

The introduction of UV Pure’s new Hallett product line addresses these upgrade challenges with new technology, higher-capacity flow rates, and lower power consumption while continuing to provide the low-maintenance, highly reliable performance that operators trust from UV Pure.

As the UV Pure team prepares to ship the first of these new Hallett systems in early 2019, we share some answers below to common questions about the new units.

How are the new Hallett units similar to UV Pure’s proven Hallett 15xs and Hallett 30 systems?

The new Hallett units are still powered by UV Pure’s patented Crossfire Technology™, which includes automatic self-cleaning wipers, smart sensors, and built-in purging to prevent fouling of the quartz sleeve by mineral scaling and biofilm. This makes Hallett systems up to 10 times more effective in difficult water applications than conventional UV systems.

How are the new Hallett systems different from existing Hallett units?

The new Hallett units have been completely redesigned with better features and operability. The new systems can handle flow rates of up to 100 gpm (378 L/min) per unit while continuing to provide robust, reliable disinfection under the toughest conditions. For higher flow applications, multiple Hallett units are connected to achieve flow up to 1 MGD (3,785 m3/day).

What happened to UV Pure’s Upstream products?

Upstream systems will be discontinued in early 2019, but UV Pure will continue to offer replacement parts and full product support for years to come. New Hallett NC systems will replace Upstream models for disinfection applications that do not require product certification or validation.

How does UV Pure ensure its systems provide the appropriate level of public health and environmental protection?

UV Pure is offering a new Hallett system that is validated to the US Environmental Protection Agency’s (EPA) UV Disinfection Guidance Manual (UVDGM) protocols, as well as to the National Water Reuse Institute’s (NWRI) UV Disinfection Guidelines for Drinking Water and Water Reuse.

What type of warranty is available for replacement lamps?

UV Pure continues to offer a 12-month limited warranty for LPHO lamps, while amalgam lamps in the new Hallett 1000 model will be covered for 16 months.

Learn More:

Click here or below to download a brochure that answers your questions about the new Hallett, or please contact us here.

 

Discover the NEW Hallett 1000: Smart new features, same trusted name

Operators can now virtually eliminate concerns about maintenance, active supervision, and performance reliability for on-site UV disinfection at commercial, industrial, and municipal water or wastewater plants up to 1 million US gallons per day (3,785 cubic metres per day). How?

UV Pure’s new Hallett™ 1000 systems have more capacity than ever, plus the performance, power, and smart technology you expect from UV Pure.

The new Hallett 1000 model builds on the success of UV Pure’s proven Hallett 30 system and patented Crossfire Technology™. This technology uses a unique elliptical reflector design with dual air-mounted lamps to deliver a high UV dose and target pathogens from 360 degrees.

New and improved features of the Hallett 1000

Longer lamp life:

Each Hallett 1000 unit is equipped with high-output, long-life low-pressure high-output (LPHO) amalgam UV lamps that are powered by a UL-certified pre-heat ballast with a soft start. This helps extend their operating life to provide maximum UV output for up to 12,000 hours, or approximately 16 months.

Larger capacity system, same reliable disinfection:

The new Hallett 1000 units can handle flow rates of up to 100 gpm (378 L/min) per unit while continuing to provide robust, reliable disinfection under the toughest conditions. For higher flow applications, multiple Hallett 1000 units are connected with a prefabricated pipe manifold to achieve flow up to 1 MGD (3,785 m3/day). This modular design provides built-in redundancy and ensures the highest level of protection since one or more Hallett systems can be shut down for service while others continue to operate.

Space-saving, easy-access vertical design:

The new Hallett 1000 systems incorporate a newly designed aluminum outer shell with side hinges that can easily be flipped open to access the internal components. This design even further reduces the Hallett installation space requirements on a wall or as part of a vertical-mounted manifold system, and allows operators to quickly change lamps without having to pull them from the fragile quartz tube.

Contact us to discuss how UV Pure’s new Hallett systems can help you meet your water disinfection needs.

Cottage owner ensures safe well water with low-maintenance UV Pure system

System Design Specifications
  • Application:  Potable water treatment
  • Location:  Cottage in Kawartha Lakes, Ontario
  • Commissioned:  September 2017
  • System:  1 – UV Pure Upstream NC 10-50
  • Flow:  10 gpm (38 L/min)
  • Minimum UV dose:  40 mJ/cm2
  • Minimum UVT:  50%

Ryerson Urban Water’s Executive Director, Nick Reid, recently purchased a cottage in the Kawartha Lakes to provide him and his family worry-free escapes from the city. However, unlike municipal water systems that use a multi-barrier approach to ensure water safety, Reid knew that many well water users have no protective barrier before the tap. That is why he opted to install a UV disinfection system for an extra measure of safety against any microbiological threat that could arise if surface water made its way into his well.

Because the property had been vacant and the well was unused for an extended period, Reid took steps to chemically disinfect and flush the well. This helped to improve the water quality but did not provide residual protection. To ensure he never had to worry about water quality, Reid wanted a UV disinfection system that would provide a high level of safety for his drinking water with minimal maintenance. So he decided to install a UV Pure Upstream NC 10‑50 unit in September 2017.

“I could have gone to a big box store and bought a conventional, off-the shelf UV disinfection unit,” says Reid, “But I wasn’t confident that those systems could provide consistent, protection without frequent cleaning. UV Pure has an excellent reputation and their Upstream system has built-in self-cleaning capabilities, which assures me that our water is disinfected and safe to drink.”

The compact, point-of-entry system was quickly installed in the basement of Reid’s cottage and operates on standard household voltage. Well water first passes through an activated charcoal filter and then a manganese dioxide cartridge. The final disinfection is provided by the Upstream unit before the water is distributed throughout the cottage.

Crossfire Technology provides reliable disinfection for drinking water

“UV Pure’s unique Crossfire Technology™ was an important consideration for me when selecting a UV disinfection system for my cottage,” Reid says. “Dual smart UV sensors continually monitor UV lamp output and water quality, ensuring the highest level of treatment and health protection. If either of these parameters does not meet the set specifications, the systems will sound an alarm, notify me and automatically shut down.”

The Crossfire Technology incorporates two UV lamps mounted in air and elliptical reflectors that enable reuse of UV energy. This design targets pathogens from 360 degrees to provide inactivation of pathogenic organisms such as E. coli, Giardia and Cryptosporidium. This also eliminates the risk of shadowing which is more likely in conventional systems and could allow live pathogens to pass through.

Contact us to discuss your UV disinfection needs.

Watch this video to learn more about UV Pure’s Crossfire Technology:

Farm provides safe drinking water to livestock with help of UV Pure systems

System Design Specifications
  • Application: Potable water treatment
  • Location: Cooper Farms – Ohio, USA
  • Commissioned: 20019
  • System: 4 – UV Pure Upstream NC 15-50
  • Flow: 15 to 60 gpm (57 to 227 L/min)
  • Minimum UV dose: 40 mJ/cm2
  • Minimum UVT: 50%

Inadequate groundwater supplies prompted Cooper Farms in Ohio to begin harvesting and reusing rainwater in 2009 as a supplement to its potable water supply and to reduce its demand on the local groundwater system.

Since one of the key uses for the treated rainwater is to provide drinking water for livestock, Cooper Farms started exploring options to implement a multi-barrier treatment process with UV disinfection that could provide pure, safe water. Rainwater can acquire a multitude of contaminants and pathogens as it is collected, so treating it to potable water quality standards is essential for preventing disease outbreaks and death among livestock.

Upon the recommendation of Flag City Water Systems, a local UV Pure representative, Cooper Farms installed a purification system that includes chemical-free UV Pure disinfection for its ability to handle low UV transmittance (UVT) conditions, a typical characteristic of the rainwater, which is collected and stored in a retention pond at the site.

UV Pure disinfection enhances system performance and provides peace of mind

“We worked closely with UV Pure to design and install a water treatment system that meets Cooper Farms’ needs,” says Brad Longberry, CEO of Flag City Water Systems. “Even after pond water is filtered, UVT can still be quite low, so the ability to consistently deliver a high UV dose under these conditions was a very important consideration for us when selecting UV Pure’s Upstream systems with Crossfire Technology for this application.”

The system at Cooper Farms is designed to treat source water to a potable standard. Currently, a small amount of well water is pumped into a retention pond which is supplemented by rainwater. The blended stream first passes through a microfiltration system that uses a specialized five-micron filter to remove organics and then dosed with chlorine.

“Once chlorination is complete, the water requires additional purification which is provided by UV Pure’s Upstream systems,” Longberry says. “UV disinfection inactivates pathogens like Cryptosporidium, Giardia and Legionella that can be resistant to chlorine. Proper UV disinfection also provides a second layer of protection to enhance the system’s performance and reliability since the changes for a potential disease outbreak are always very real for Cooper Farms.”

The final disinfection in each system is performed by one to four Upstream NC 15-50 systems that are each sized to handle flows from 15 to 60 gpm (57 to 227 L/min) of water, with UVT as low as 50%.

Crossfire Technology targets pathogens from every angle

UV Pure’s Crossfire Technology incorporates elliptical reflectors that reuse light energy to deliver a high UV dose and target pathogens from 360 degrees.

Dual smart UV sensors in the Upstream systems continually monitor UV lamp output and water quality to ensure the highest level of treatment is consistently delivered to protect Cooper Farms on an ongoing basis. If either of these parameters does not meet the set specifications, the systems will sound an alarm, notify the operator and automatically shut down.

“Overall, our partnership with UV Pure has been excellent,” Longberry says. “As a UV Pure distributor for the last 20 years, Flag City has received great technical support and fantastic systems in a timely fashion.”

Learn more about UV Pure’s Crossfire Technology.

Contact us to discuss your UV disinfection needs.

For UV Pure sales and service in Ohio, contact Flag City Water Systems.

Contact information:
1705 Romick Parkway
Findlay, Ohio 45840
419-423-8082
info@flagcitywater.com
www.flagcitywater.com