Municipalities throughout the world are choosing TrojanUV systems for their disinfection upgrade and chlorine conversion projects. When you're ready to start planning your project, let's talk.

In the meantime, this Q & A will provide you with information and insight. In it, Wayne Lem (TrojanUV Market Manager) discusses the benefits associated with upgrading an older UV system and Frank Cassisi (Director of Wastewater Operations for the Borough of Hollidaysburg, PA) talks about his recent upgrade project and offers advice to other wastewater treatment plant operators.

What are some telltale signs that a UV equipment upgrade is necessary?

Lem: The most evident signs are those that are observed through periodic inspection of the UV system. Visible wear and tear and corrosion of vital system components are signs that operators should always be looking for.

Also, if the system is becoming more expensive to operate (e.g., power consumption), or if you notice that maintenance is becoming not so routine anymore, and that more time is being spent servicing the system than it was in the past, it is likely time to start looking at the upgrade options available to you.

The core components of a UV system consist of UV lamps, ballasts, and electronic circuit boards. As we all know, new electronic components generally replace older technology every few years. Take mobile phones, tablets, and computers, for example. We often see them become outdated in two or three years. Similarly, though perhaps not as quickly, a UV system’s electronic ballasts and circuit boards (used for a UV intensity sensor) also have limited useful life expectancies. Not only that, but as components age, they may become more difficult to replace and keep in stock.

Significant innovation has occurred in the 15 to 20 years that many UV systems have been in operation. Advancements associated with system efficacy, simplified maintenance, and energy efficiency have been introduced, all of which correlate to cost savings.

What are the typical barriers that keep treatment operations from moving forward with UV system equipment upgrades?

Lem: One main barrier to UV equipment upgrade is often an insufficient capital budget to proceed with an upgrade. In these cases, wastewater treatment plants make do with their aging equipment for another year or so and come up with a “Band-Aid” solution until they find the funding for the upgrade. This temporary solution almost always results in higher operational costs in the form of increased maintenance and parts to keep the equipment running. With newer UV systems today boasting a reduced lamp count and being more energy efficient than their predecessors, the payback could be as little as three years, based on the significant operation and maintenance savings.

In some cases, another potential barrier may simply be a lack of education or awareness of what is involved in a UV upgrade. Some operators or superintendents might not know of other, perhaps neighboring, treatment plants that have undertaken a similar UV system replacement/upgrade project — so they are unaware of the available options, the process, and the associated benefits.

Why did you decide to upgrade the UV system in Hollidaysburg?

Cassisi: We decided to upgrade due to the fact that our old TrojanUV system was 20 years old and past its useful life.

Once a treatment operation has decided it’s time to upgrade, what does it need to consider before doing so? What special obstacles come into play for a UV equipment upgrade?

Lem: There are obviously many moving parts to these types of projects, and several different stakeholders must work together. Thoughtful planning and collaboration is crucial. At Trojan, we are in continual communication with the various stakeholders and provide step-by-step instructions to contractors to ensure a smooth teardown of the old system and successful installation of the new one.



It’s important to understand the amount of civil and electrical work involved in the project and imperative that a plan be put in place to ensure continuous, effective disinfection while the old system is being removed. Many of our customers take advantage of our mobile disinfection trailer — it can be easily plumbed to disinfect the existing effluent, providing disinfection during the upgrade.

What are the design factors that have to be considered with a UV upgrade?

Lem: It’s important to consider what has changed since the original equipment installation, both in terms of plant process design and permit requirements. It may also indicate any changes that could be expected in the future. This includes items such as:

• Flow rates (average and peak): Are they increasing, decreasing, or staying the same?
• Disinfection requirements: Is there a chance that the plant might want to integrate water reuse processes in the future?
• Available footprint: Can the existing channel be utilized, or does a new channel need to be designed and constructed? Many new UV systems are designed to fit into existing or smaller spaces, and this can be a significant cost savings.
• Head loss and hydraulic profile: It’s critical to ensure the new UV system fits within the hydraulic profile, as it is likely that lamp count, configuration, and channel dimensions will change, ultimately affecting overall head loss.
• Maintenance: What do operators like or dislike about their current system? New UV systems have been designed to overcome the operation and maintenance challenges associated with older systems, such as cleaning and high lamp count.

What advice can you offer other operators and superintendents who are thinking about upgrading their UV systems or converting from chlorine?

Cassisi: A UV upgrade should not be thought of as a monumental task or a major civil works project. UV is a much better way to disinfect than chlorine. You don’t have to handle harsh chemicals. There is no chemical injection system to worry about or maintain, and there’s no need to have a preparedness, prevention, and contingency plan in place for chlorine leak incidents.

UV systems are easy to operate and will be more cost effective in the long term.

What kind of impact has the upgrade had on the wastewater treatment plant in Hollidaysburg, and what kind of benefits are you seeing?

Cassisi: In working intimately with TrojanUV, our upgrade was relatively simple and we quickly realized the benefits of a newer UV system.

The new system has been running exceptionally well. Besides routine lamp change-outs, our staff has spent hardly any time maintaining the system.

I have seen several different brands of UV systems in operation and have found the TrojanUV system to be far superior in all aspects.

• Download the Q & A [PDF]

For the past few decades, and increasingly today, UV has been successfully used around the world for municipal wastewater disinfection. As a growing alternative and a direct replacement technology to chemical (chlorine) disinfection, UV does not produce harmful by-products and is non-toxic to the environment.

In this Q & A, Wayne Lem (TrojanUV Market Manager) sheds light on the differences between the two disinfection options.

What are the most commonly used alternatives for disinfecting treated wastewater?

Lem: Traditionally, the use of chlorine gas was the most common method of wastewater disinfection. Chlorine gas itself is relatively inexpensive but is a highly toxic chemical that must be transported and handled with extreme caution. It is stored under pressure in large tanks and is released into the wastewater as a gas. Sodium hypochlorite is a diluted liquid form of chlorine that is also commonly used.

Today, UV disinfection is widely accepted for municipal wastewater disinfection around the world. UV is rapidly growing, given it’s a safe and cost-effective alternative over chemical disinfection. Also, it produces no disinfection by-products or a chlorine residual, which is harmful to the environment. The UV disinfection process adds nothing to the water but UV light, and therefore, has no impact on the chemical composition of the water.

How effective is UV at destroying pathogens, as compared to chemical disinfection methods?

Lem: UV is a very cost-effective and a reliable technology that protects the public against pathogenic microorganisms, including protozoa, bacteria, and viruses. Chemical disinfection using chlorine is also effective against these pathogens; however, there are pathogens such as Cryptosporidium and Giardia which are chlorine-resistant but can be disinfected by UV light.

Unlike chemical approaches to water disinfection, UV provides rapid, effective inactivation of microorganisms through a physical process. The retention time required to achieve disinfection ranges from a few seconds compared to several (>30) minutes for chlorine disinfection. This eliminates the need for large chlorine contact chambers, thereby reducing the required footprint and cost of installation.

Are there any employee safety issues involved with operating a UV disinfection system?

Lem: There should be safety plans in place for any disinfection technology used. The safety risks for operating a UV system, although low, are related to operator exposure to high levels of UV light and possible electrical hazards. The exposure to UV light is very low given that UV light is shielded from operators by channel grating and “light locks.” As well, there are lock-outs in the power cabinets to ensure power is off, and lock-out/tagout occurs when servicing a UV system. As with operating and working with any type of equipment, it is recommended that proper personal protective equipment (PPE) be worn and safety procedures be followed.

Owners and operators of UV disinfection systems should have operational practices in place. These are generally provided in the O&M manual from the UV system supplier and cover several items, including:

1. Procedure for lamp maintenance and replacement
2. Procedure for monitoring the system operation
3. Proper disposal of UV lamps, ballasts, quartz sleeves, and other components

What type of public safety concerns are associated with the use of UV disinfection versus chlorination?

Lem: The advantage that UV disinfection is a physical process and does not alter the quality of the water also makes it a perceived disadvantage, in that it does not leave a residual for monitoring. Without a residual, there may be a concern that the UV dose is low and pathogens are not being adequately disinfected, and/or pathogens can sometimes repair and reverse the destructive effects of UV through a “repair mechanism,” known as photoreactivation, or in the absence of light known as “dark repair.”

Although these may be legitimate concerns, they can be overcome by working with a UV supplier with proper sizing tools and expertise in leading-edge controls and monitoring.

Through proper sizing, an adequate UV dose can be delivered to prevent photo reactivation. Furthermore, through incorporating a robust and calibrated UV lamp intensity sensor for dose control, the realtime UV dose for the system can be monitored and controlled to ensure continuous adequate disinfection.

How do employee training requirements compare for UV as opposed to chlorine gas or hypochlorite disinfection methods?

Lem: In comparison, facilities with chlorine systems may need to institute a full Risk Management Program as specified by the U.S. Environmental Protection Agency, as well as a process safety management program required by the Occupational Safety and Health Administration. Training and operational controls for these programs are extremely time consuming and expensive.

What costs should be considered in the 20-year lifecycle cost evaluation for a new facility requiring disinfection?

Lem: The cost of chlorination equipment is typically a small part of the overall capital cost. Because chlorination requires a lengthy retention time, a large chlorine contact tank or channel is required unless one already exists. This adds additional concrete, civil works, excavation, and construction to the overall capital cost.

Due to the hazardous nature of chlorine gas, an emergency scrubber system and an enclosed building may need to be installed to protect operators and the surrounding community from a dangerous chlorine gas leak.

Sodium hypochlorite (liquid chlorine) has similar equipment and chlorine contact tank costs as chlorine gas. However, if the hypochlorite is delivered to the plant, there will be additional costs associated with building storage facilities to store this corrosive chemical.

The large volumes of hypochlorite required means large storage tanks are needed, thereby increasing the total capital cost. If UV equipment is to be retrofitted into an existing chlorine contact tank, the majority of the cost will come from the equipment, and additional space can be reclaimed because of UV’s small footprint. If a concrete channel is to be constructed, the cost to accomplish this is significantly smaller compared to chlorine since the footprint of a UV system is much smaller. UV disinfection occurs in seconds, whereas chlorination requires several minutes of retention time.

The annual cost of operating and maintaining a disinfection system can have a significant impact on the economic evaluation of each option. The operations and maintenance costs include the cost of chemicals, electricity, replacement parts, and labor required to maintain each system.

The hazards of chlorine gas results in a significant amount of investment into training staff, emergency preparedness planning, and maintaining the chlorine system. Chlorine gas prices are relatively low, but this is often outweighed by the intensive maintenance and safety precautions needed for the system.

Due to the corrosive nature of chlorine, piping and pumps are prone to leaks and scaling and subsequent replacement. Scaling buildup in piping and pumps requires regular acid cleaning to remove.

Therefore, these ongoing maintenance costs associated with chlorination systems must be addressed when comparing disinfection alternatives. The O&M costs associated with UV consists primarily of lamp replacement costs and the electrical cost of operating the UV system.

Are there economic or other advantages to be had by retrofitting existing chemical disinfection facilities to UV?

Lem: The cost of retrofitting an existing chlorination system to UV is a common economic evaluation and often reveals UV having the lowest lifecycle cost. The capital cost of a UV system is higher than a typical sodium hypochlorite system.

Fortunately, the operating cost of a typical UV system is significantly lower than a hypochlorite system due to the increasing cost of chemicals. The retrofit of an existing hypochlorite system to UV has a higher initial capital cost, but over a span of a few years, the cost of the UV system would provide a return on investment.



This chart above shows the accumulated net-present value cost of UV and sodium hypochlorite for an actual wastewater treatment plant in New Jersey, USA. Based on a design flow of 16 MGD and average flow of 10 MGD, the cost of the UV system would almost equal the cost of staying with hypochlorite in five years. Over the long-term, UV becomes the more costeffective solution at this plant.

• Download the Q & A [PDF]

>> Press Release [PDF]

More TrojanUVSigna™ News

• TrojanUVSigna™ Approved by California Water Board For High-Level Water Reuse Applications
• Installation of TrojanUVSigna™ Marks New Era of Cleaner Waterways For Chicago

Governor General of Canada, David Johnston (left), Professor of Drinking Water Safety at Tsinghua University, Wenjun Liu (middle), and Trojan's Dongming Lu at Tsinghua University's School of Environment's Drinking Water Safety Laboratory.

More About UV Disinfection in China

In China, the use of ultraviolet light is an established method for the disinfection of treated wastewater before it is discharged back into lakes, rivers and streams. TrojanUV alone has supplied UV equipment to hundreds of wastewater treatment plants throughout the country.

Highly favorable reviews of UV technology in wastewater applications influenced Tianjin Economic Development Area (TEDA) Water Supply to investigate the potential of using UV for drinking water applications at one of its Tianjin water treatment plants.

• Read the case study

In an effort to modernize and improve its wastewater management, the India Central Pollution Control Board (CPCB) has set new wastewater discharge standards. These standards in combination with the growing adoption for public-private partnership (PPP) models provide the needed funding to help accelerate the construction of new municipal wastewater treatment plants.

Many of these new plants will be constructed to treat wastewater before it is discharged into the Ganga. The Ganga is a river that starts in the Himalayas, and after traversing a course of more than 2,500 km through the plains of north and eastern India, merges with the Bay of Bengal.

The Clean Ganga Project

The Government of India has made a commitment to clean up this river which is regarded as the most important river in India with significant economic, environmental and cultural value. This project, called the Clean Ganga Project, was started in 2014 after Narendra Modi became the Prime Minister of India.

This is an extremely important initiative, and TrojanUV is proud to play a role in educating stakeholders throughout the region and creating awareness of UV disinfection.

The TrojanUV3000Plus™ is currently being installed at the Varanasi Sewage Treatment Plant in Uttar Pradesh, India to disinfect 120 MLD (5,000 m³/hr) of wastewater before it discharges into the river. The system design consists of two duty channels with one bank of lamps per channel, 31 modules per bank, and 496 lamps.


These concrete channels will house the TrojanUV3000Plus disinfection system at the Varanasi Sewage Treatment Plant.

UV disinfection gives the Government of India an effective way to disinfect wastewater. UV has significant cost, safety and environmental benefits compared to chemical (chlorine) disinfection and has been proven effective in thousands of installations globally.

More About Water Reuse

When it comes to wastewater disinfection, two common methods are widely used today: chemical and physical. Chemical disinfection is typically achieved by chlorine gas or hypochlorite whereas physical disinfection is by UV light. An increased awareness of the disadvantages of chemical disinfectants, specifically chlorine, continues to prompt wastewater treatment plants to convert to UV.

Take the City of Hot Springs, Arkansas for example. Officials there decided to convert the disinfection at its regional wastewater treatment plant from chlorine to UV. This was done in an effort to eliminate the safety issues associated with chlorine, and to also protect and improve receiving waters.

UV is Effective, Safe & Environmentally Friendly

With chemical disinfection, the effluent is exposed to chlorine gas (or liquid chlorine) in large tanks to ensure sufficient contact time to kill microorganisms. However, in some jurisdictions regulations place stringent limits on chlorine levels in the final effluent to minimize disinfection by-products being discharged into receiving water. In those cases, an additional chemical process called dechlorination is required to remove residual chlorine, ultimately adding more complexity and cost to the disinfection process.

Alternatively, UV provides an effective, safe and environmentally friendly way to disinfect wastewater. It has significant benefits compared to chlorine and has been proven effective in thousands of installations globally. Furthermore, UV is not affected by temperature or pH of the effluent and does not create disinfection by-products. 

More About Upgrading a UV System

• By upgrading to a new TrojanUV system for their wastewater treatment plant, the Honouliuli Water Recycling Facility in Hawaii will see significant energy savings, as power consumption will be reduced by up to 75%. Read the case study.

• In order to improve the treatment performance and ensure that it would eventually have the treatment capacity to meet future population growth equivalent of up to 225,000, Swansea WwTW was in need of an equipment upgrade. Read the case study.

• Wayne Lem (TrojanUV Market Manager) discusses the benefits associated with upgrading an older UV system and Frank Cassisi (Director of Wastewater Operations for the Borough of Hollidaysburg, PA) talks about his recent upgrade project and offers advice to other wastewater treatment plant operators. Read the Q & A.

Spanish minister of Agriculture, Fisheries, Food and Environment, Isabel García Tejerina, inaugurated the new Ourense Wastewater Treatment Plant (WWTP) on July 26 2017.

Our role in the project was featured in the October 2017 edition of “Environmental Projects, Technology, and News” Digital Magazine. Read the article here.

The Investment

A total of €59 million was invested in the Ourense WWTP project which has provided the city of Ourense with an infrastructure that enables compliance with European Directives on wastewater treatment.

The facility will serve a population of 350,000 compared to the previous capacity of 88,000, and the maximum daily treatment flow will be tripled (from 24,640 m³/d to 72,000 m³/d). The new plant will also enable the treatment of 100% of the stormwater received at the facility.

The UV Solution

The TrojanUVSigna™ was selected for UV disinfection at the new facility. For wastewater disinfection, the TrojanUVSigna™ offers low total cost of ownership and drastically simplified operation and maintenance compared to alternative systems. Since it's introduction in 2010, it has been installed in a variety of applications – around the world – disinfecting primary and secondary effluents as well as tertiary / water reuse.

• Learn more about the benefits of TrojanUVSigna™

Here are some of the highlights from the Conference:

What is ECT?

ECT is a term used to describe an advanced water treatment process that focuses on targeting the removal of chemical compounds which can pose significant health risks or diminish aesthetic water quality and therefore compromise the overall integrity of a water source.

Why is ECT so important in drinking water treatment? What experience does Trojan have?

The treatment of drinking water is regulated globally and drinking water treatment is heavily monitored to ensure biological contaminants including bacteria, protozoa and viruses do not pose risks to public health. The removal of chemical contaminants generally requires treatment methods that are more advanced than those established for biological contaminant treatment.

However, increasing global population is driving demand for quality drinking water. With population growth, more and more, cities are forced to rely on water sources that are exposed to chemical contamination. Trojan has helped dozens of municipalities destroy chemical compounds or contaminants in their drinking water to provide water that is safe and aesthetically-pleasing.

What is UV-AOP technology?

UV-AOP (Ultraviolet – Advanced Oxidation Process) is the treatment process offered by TrojanUV for ECT. TrojanUV was one of the first to commercialize this process for the treatment of chemical contaminants in water. The process is driven by UV-light which is capable of weakening or breaking the chemical bonds of contaminants, therefore directly destroying many trace chemical contaminants found in water.

This process is referred to as photolysis (photo = light; lysis = disintegration). In addition, UV-light can produce powerful oxidizing agents called hydroxyl radicals when hydrogen peroxide is added to water upstream of a UV system (through photolysis of hydrogen peroxide). These radicals are highly unstable and react with chemical contaminants immediately after they are formed.

What interest is there with UV-AOP for drinking water treatment in China? How does it work?

China extracts a significant amount of its drinking water from surface waters that are prone to algae blooms. When algae die, they are known to release the chemicals 2-methylisoborneol (MIB) and geosmin which can be difficult to treat by traditional drinking water treatment processes.

This results in the earthy and musty tastes and odors in the finished drinking water. Regions of China, specifically the province of Shandong, have serious taste and odor events in their drinking water and the government is funding AOP technology to improve their drinking water quality.

What solutions does Trojan offer for UV-AOP technology?

TrojanUV is the leading supplier of ECT systems for taste and odor removal. Our UV systems utilizing hydrogen peroxide as an oxidant (with the hydrogen peroxide and delivery system sometimes supplied by our own USP Technologies) are capable of removing compounds attributed to the unpleasant taste and odor in drinking waters.

Our vast knowledge of ECT is backed by our scientists who possess the fundamental understanding of the science behind contaminant treatment and are increasing their knowledge through further research in this area.

Further Reading

• Learn more about the UV-oxidation process
• Learn more about TrojanUV ECT systems
  

Ask an ECT Expert

Have a question about environmental contaminants, our TrojanUVSwift™ECT or TrojanUVPhox™? Want to discuss a project or application? Email our ECT Manager at ect(at)trojanuv(dot)com

The Groundwater Replenishment System (GWRS) in Orange County, California is the largest indirect potable reuse project of its kind in the world. Our TrojanUVPhox™ plays an important role in the facility's treatment train.

This video explores the UV-oxidation stage of the advanced water treatment process at the GWRS in Orange County, and is shown to tour groups visiting the facility.

Benefits of UV-oxidation

A dual process of UV photolysis and UV-oxidation ensures finished water at the facility is free of chemical contaminants and harmful microorganisms. This is a cost-effective, energy effective and highly-effective treatment for purified recycled wastewater. The water is reused to provide protection against drought and as a means of achieving a sustainable water supply.

• Learn more about UV-oxidation systems

Media Coverage

• OC Aims to Break World Record for Water Recycling (NBC)
• California Aims To Get Past The Yuck Factor Of Recycled Wastewater (NPR)
• From waste to taste: Orange County sets Guinness record for recycled water (Orange County Register)

In a recent edition of Treatment Plant Operator (TPO) feature, the Rocky Mount Wastewater Treatment Plant shared that cross-training, and a wealth of experience in wastewater treatment by their team members allows them to be highly self-reliant and do most of their own maintenance. It is this confidence in their capabilities and their treatment process that earned the facility the designation as a benchmark plant for its maintenance practices and performance record by the Virginia Department of Environmental Quality.

Two TrojanUV systems disinfect the effluent at the plant located in the Blue Ridge Mountain region of Virginia. Tim Burton, plant superintendent, gives credit to UV disinfection for his ability to save money and assure a near-100 percent pathogen kill rate.

The UV Upgrade

The plant first adopted UV disinfection in 1994, after a conversion from chlorine. Two channels of TrojanUV3000™ equipment were installed; each channel had a capacity of 3 MGD and was designed for alternating use. In 2012, one of the channels was upgraded to the newer TrojanUV3000Plus™ system which has yielded significant operating cost savings (for cleaning and electrical costs).

 
The TrojanUV3000Plus™ is one of the reasons why UV treatment is now a favored technology in wastewater treatment. This highly flexible system has demonstrated effective and reliable performance in thousands of installations around the world. It is well suited to wastewater disinfection applications with varying flow rates and influent, and offers dependable performance, simplified maintenance and maximized UV lamp output at end-of-lamp life.

More TrojanUV3000Plus™ News & Further Reading

• Treatment Plant Operator Article: Experience and Cross-Training Make Rocky Mount Team Members Highly Self-Reliant
• TrojanUV3000Plus™ Brochure

Our first open-channel UV systems were installed in the mid-1980’s; by the 1990’s UV systems had become mainstream and were widely adopted for wastewater disinfection. Since then, innovation in UV equipment and technology has continued, with revolutionary advancements along the way that have changed the way we think about UV.

Today, our newer systems offer significant energy, labor and maintenance savings, thanks to the latest in lamp technology, sleeve cleaning and controls/automation.

• Download the What's New in UV fact sheet

New Lamp Technology

Fewer lamps (up to 1/ 3^rd) are needed to treat the same flow thanks to new technology that can pump out up to 1000 Watts per lamp. As lamps have become more powerful, they have also become more energy efficient, saving users up to 66% energy. Improved controllers can help realize even more savings. For example, new controllers can automatically adjust lamp power during periods of low flow or changing water quality to conserve energy and extend lamp life, all while ensuring your required dose is being met.

Labor Savings

In new UV systems, there are up to 1/3rd fewer lamps to maintain and new controller and sleeve cleaning technology that can simplify an operator’s daily work. Smart controllers have expanded the capabilities available for monitoring and automating UV system functions, including diagnostics and alarms. Our ActiClean sleeve cleaning system saves hours of maintenance time by automatically cleaning quartz sleeves to prevent fouling.

Innovation to Installation

With over 10,000 municipal UV installations, we have many examples of UV innovation in action. One such example is in Chicago; The Metropolitan Water Reclamation District of Greater Chicago (MWRD) – of which the Terrence J. O’Brien Water Reclamation Plant (WRP) is part of – has made a number of upgrades to its treatment process over the years. The addition of UV disinfection was a critical part of these upgrades; it played a key role in improving water quality throughout the Chicago Area Waterway System (CAWS).

• Learn more about the Terrence J. O’Brien WRP and the TrojanUVSigna installed there

More About UV Disinfection in India

• Blog post: UV to Play an Important Role in Protecting India’s Ganga

We were featured in the Autumn edition of Water Reuse & Desalination magazine with our article “Chlorine Improves UV-AOP Efficiency in Site-specific Conditions”. In the article, our Adam Festger and Scott Bindner outline when it makes practical and economic sense to use chlorine as the oxidizing agent in an ultraviolet advanced oxidation process (UV-AOP) for potable reuse.

Below is a summary of the article and also a link to the full article.

Hydrogen Peroxide is the Most Commonly Used Oxidant for UV-AOP

UV-AOP is a process in which UV, along with an oxidant, removes chemical contaminants such as 1,4-dioxane, algal toxins, pharmaceuticals and pesticides from water. The most common oxidizing agent in use today is hydrogen peroxide (H₂O₂), which is used at facilities around the world, including the Orange County Water District’s world-renowned Groundwater Replenishment System.

The Orange County Water District’s world-renowned Groundwater Replenishment System uses hydrogen peroxide as the oxidant for their UV-AOP process.

Exploring Chlorine as an Oxidant

Recently, research has been undertaken to explore chlorine (sodium hypochlorite and  NaOCl) as an oxidant for UV-AOP. The data shows that under the right conditions, UV-AOP with chlorine can provide significant cost savings compared to UV-AOP with H₂O₂. These ideal conditions are often presented in potable reuse applications.

When UV-Chlorine AOP Makes Sense

Using chlorine as the oxidant in an AOP makes practical and economic sense when:

1. The pH of the water entering the UV-AOP system is less than 6.0
2. Ammonia levels entering the UV-AOP system are low (e.g. under 0.25 ppm)
3. Quenching of residual H₂O₂ would be required to prevent regrowth in transmission lines. UV-chlorine removes the quenching step altogether.
4. Chlorine is already in use at a facility for other treatment processes

UV-Chlorine AOP at The Albert Robles Center for Water Recycling and Environmental Learning

The Water Replenishment District of Southern California is currently constructing The Albert Robles Center for Water Recycling and Environmental Learning (ARC). This facility will implement an advanced wastewater treatment process for potable reuse which incorporates ultrafiltration (UF), reverse osmosis (RO) and UV-chlorine AOP.

The Water Replenishment District of Southern California’s Albert Robles Center for Water Recycling and Environmental Learning has site conditions that make chlorine the best choice for the oxidant in their UV-AOP. 

The facility will control ammonia levels passing through RO, and by way of UF and RO, pH levels will remain low. If the facility had used H₂O₂ as an oxidant, quenching would have been required; therefore they have eliminated this step by using chlorine. ARC has the ideal site conditions to allow them to take advantage of the cost savings offered by using UV-chlorine for their AOP.

Further Reading

• Full Article
• Autumn Issue World Water: Water Reuse & Desalination (article on Page 16) 

About The Authors

Adam Festger: Adam is the Business Development Manager for Potable Reuse at Trojan. Given increasing global water scarcity, he is focused on expanding the use of UV light to convert wastewater into drinking water. He holds a Master’s Degree in Hydrology and a Bachelor of Science in Mechanical Engineering from the University of Arizona. He has over 15 years of experience in contaminant treatment and UV technologies and is a member of the International Ultraviolet and WateReuse Associations.

Scott Bindner:  Scott has spent over 7 years acting as a Market and Applications Specialist for UV Advanced Oxidation Systems at TrojanUV.  He has a Master’s in Biochemisty and a Bachelor of Medical Science Degree in Microbiology and Immunology.  

Extreme Weather Events on the Rise

Year after year, the world is seeing more frequent extreme weather events, whether it is droughts, extreme temperatures, floods, or severe storms. These weather events can have immediate and undesirable impacts on water treatment facilities and the health of receiving water bodies.

For wastewater treatment plants, large amounts of rainfall or snowmelt can outpace peak flow capacities resulting in sewer overflow, where untreated (or partially untreated) wastewater is discharged, polluting receiving waters. In combined sewer systems, overflows contain not only human waste, but industrial and toxic waste.

Combating Pollution Caused by Combined Sewer Overflows

The pollution caused by combined sewer overflows (CSOs) is becoming a priority concern for countries around the globe. Enter INTCATCH, a Horizon 2020 program funded by the European Union and led by Brunel University in collaboration with 20 partner organizations across seven countries. The team is installing CSO treatment systems along with state-of-the-art monitoring tools that can measure water quality in real-time. The vision is to build the program so that any city or town can use these systems and tools to uncover how best to improve the health of their water source affected by CSOs.

Demonstrating INTCATCH in Villa Bagatta, Italy

Villa Bagatta, Italy, lies on the coast of beautiful Lago di Garda (Lake Garda) and is home to one of five INTCATCH demonstration sites, with other sites located in the UK, Greece and Spain. Lake Garda is the largest lake in Italy and a very popular tourist destination. They currently have 22 pumping stations and gravity CSO channels and 10 submerged CSO tunnels, which were designed years ago when there were fewer peak flow events. Now, with more frequent wet weather, Lake Garda is at risk of high pollution from CSOs.

Lake Garda, Italy

INTCATCH begin building Villa Bagatta’s demonstration site in January 2018, when they installed the CSO treatment system comprised of a Salsnes Filter rotating belt filter system, a granular activated carbon filter and a TrojanUV3000PTP UV disinfection system. From January to October, CSOs were simulated using different combinations of raw wastewater and water from Lake Garda and put through the system. Now and until the demonstration ends in the year 2020, real CSO events are being treated by the system.

The demonstration site in Villa Bagatta, Italy: a Salsnes Filter rotating belt filter left in blue container, granular activated carbon filters center, and a TrojanUV3000PTP UV disinfection system far right.

Rotating Belt Filter & UV Disinfection Technology

The Salsnes Filter system is housed in a 20 foot container. Inside, a SF1000 filter (with 90 micron filtermesh), polymer station, mixer and Control Power Panel treat flows up to 50m³/h, removing, on average, 39% of suspended solids. The SF1000 performs solids separation and then transports solids to its integrated sludge thickening stage after which sludge is dropped into a collection area. The Air Knife automatic cleaning system uses compressed air to remove any remaining sludge from the filter as it rotates.

The Salsnes Filter system is housed in a 20 foot container and removes, on average, 39% of suspended solids from incoming flows.

The TrojanUV3000PTP UV disinfection system is the final treatment step, destroying bacteria, protozoa and viruses before discharging into Lake Garda. UV disinfection is a physical process that instantaneously neutralizes microorganisms as they pass by UV lamps submerged in the effluent. The process is environmentally friendly and chemical-free; it adds nothing to the water but UV light, and therefore, has no impact on the chemical composition or the dissolved oxygen content of the water.

The TrojanUV3000PTP UV disinfection system is the final treatment step, destroying bacteria, protozoa and viruses before discharging into Lake Garda.

Monitoring Water Quality in Real-time

A number of monitoring tools are in place to show the efficiency of treatment equipment and its effect on lake water quality, including levels of solids/turbidity, pH, heavy metals and E.Coli. Remote-controlled boats and fixed sensors test the water in real-time and are linked to a decision support system (DSS) that helps improve day-to-day decisions about where, when and how to best help the lake.

Remote-controlled boats test Lake Garda’s water quality in real-time.

The Future of INTCATCH

The INTCATCH program, using well-known and proven treatment technologies, combined with ultramodern monitoring tools, has the potential to help communities around the world reduce pollution caused by CSOs and improve the health of their water bodies.

Once the Villa Bagatta demonstration ends in the year 2020, INTCATCH’s mission will be just that – to find other communities that could benefit from the innovative program they’ve built.

Related reading

The Clean Ganga Project: The Government of India has made a commitment to clean up the Ganga River. This project, called the Clean Ganga Project, was started in 2014 after Narendra Modi became the Prime Minister of India.

The TrojanUV3000Plus™ is currently being installed at the Varanasi Sewage Treatment Plant in Uttar Pradesh, India to disinfect 120 MLD (5,000 m³/hr) of wastewater before it discharges into the river.

Words on Water Podcast: At WEFTEC 2018, TrojanUV sat down with Travis Loop to discuss the importance of the Ganges River to the people of India and the major effort underway to reduce pollution in the river, including new wastewater discharge standards.