disinfection

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Feb 10, 2009 - Regional Sales Manager (WWD). Fred Ferris [email protected] 847.391.1003. (Arlington Heights office). Regional Sales Manager (WWD).

A Supplement to Water & Wastes Digest & Water Quality Products

WATER disinfe disin fec ction

2009 A Guide to Current Disinfection Technologies & Applications

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contents X 2009

A Supplement to Water & Wastes Digest & Water Quality Products

04 Keeping Water Safe Editor’s Letter

05 Ozone: A Natural Phenomenon An overview of ozone generation processes

07 Chlorine Conversion Conversion from gas to liquid disinfection at W.R. Wise Water Treatment Plant yeilds significant improvement in water quality

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Solution for Water Scarcity Treating trace contaminants and disinfecting with UV in water reuse

13 Advancing Technology Disinfecting residential wastewater with UV

16 How Effective is that UV System?

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The disinfection ability of a UV system depends on proper lamp maintenance

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Cover photo courtesy of WHO/P. Virot

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6editor’s letter

Keeping Water Safe

W

ater is essential. It makes up 50% to 70% of an adult’s total body weight, and without it, survival time is limited to a matter of days. Globally, people are confronted with many problems relating to water. It is estimated that 1.5 to 2 billion people in the world lack access to safe potable water. Thirdworld countries specifically continue to be plagued by water-related diseases; however, even developed nations confront water problems. It comes as no surprise that the latest research shows that world demand for water disinfection products is projected to approach $7 billion by 2012, according to the Freedonia Group, a leading international industrial research company. Currently, the U.S. remains the largest water disinfection market; however, developing nations, such as China and India, are expected to register the fastest growth. Essentially, all U.S. utilities using surface water supplies and some using groundwater are required to use some form of disinfection. Under the U.S. Environmental Protection Agency Ground Water Rule, more utilities will be expected to disinfect in the near future. Primary methods of disinfection are chlorination, chloramines, ozone and ultraviolet light. Other disinfection methods include chlorine dioxide, potassium permanganate and nanofiltration. When determining which disinfectant to use, utilities must consider various factors, including water quality, onsite manufacturer of the disinfectant, disinfectant volume, resiliency, community safety and of course overall cost. Furthermore, traditional disinfection techniques can create additional challenges such as unwanted disinfection byproducts. In a continued effort to deliver information to water and wastewater treatment professionals, Water & Wastes Digest and Water Quality Products are pleased to bring you Water Disinfection—A 2009 Guide to Current Disinfection Technologies and Applications. We hope this comprehensive guide will offer valuable information and keep you informed of the safest and most effective methods of water disinfection.

Scranton Gillette Communications, Inc. 3030 W. Salt Creek Ln., Ste. 201, Arlington Heights, IL 60005-5025 tel: 847.391.1000 • fax: 847.390.0408

editoria l staf f [email protected] or [email protected] Editorial Director Managing Editor (WWD) Managing Editor (WQP )

Neda Simeonova Clare Pierson Stephanie Harris

Associate Editor

Caitlin Cunningham

Associate Editor

Rebecca Wilhelm

Graphic Designer

Melissa Rosenquist

Production Editor

Jason Kenny

Web Editor

Adam Terese

Web Production Editor

Morgan Jeffrey

advertising & sales 6900 E. Camelback, Ste. 400, Scottsdale, AZ 85251 tel: 480.941.0510 • fax: 480.423.1443 Regional Sales Manager (WWD) [email protected]

David Rairigh 480.941.0510, ext.25

Regional Sales Manager (WWD) [email protected]

Eric Smith 480.941.0510, ext.14

Regional Sales Manager (WWD) [email protected]

Fred Ferris 847.391.1003 (Arlington Heights office)

Regional Sales Manager (WWD) [email protected]

Brenda Yanez 480.941.0510, ext.12

Regional Sales Manager (WWD) [email protected]

Lori Glenn 480.941.0510, ext.17

National Sales Manager (WQP ) [email protected]

Don Heidkamp 847.391.1047 (Arlington Heights office)

Regional Sales Manager (WQP ) [email protected]

Heather Madril 480.941.0510, ext.24

Reprint Coordinator [email protected]

Adrienne Miller 847.391.1036 (Arlington Heights office)

ma nagement Vice President/Publisher Associate Publisher Director of Production Operations Production Manager VP Events VP Custom Publishing & Creative Services Director of Circulation

Dennis Martyka [email protected] Greg Tres [email protected] Judith H. Schmueser [email protected] Scott Figi [email protected] Harry Urban [email protected] Diane Vojcanin [email protected] Mike Serino [email protected]

corporate Chairperson

Neda Simeonova, editorial director [email protected]

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President/CEO Sr. Vice President Chairman Emeritus

K.S. Gillette E.S. Gillette A. O’Neill H.S. Gillette (1922-2003)

Water Disinfection 2009

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6focus on ozone

Ozone:

A Natural Phenomenon

W By Jack J. Reiff

hat Mother Nature performs, science tries to duplicate and then works to improve upon. Ozone—created by a natural

phenomenon—provides many benefits to mankind that science had to harness the energy and recreate the process. This seemingly simple process that takes place naturally in the environment has taken the industrial society a long time to perfect.

An overview of ozone generation processes

When stimulated by either an electrical charge or ultraviolet (UV) light (specific wavelength) the oxygen molecule (O2) breaks up and temporarily joins other oxygen molecules, forming ozone (O3) or other levels of ozone depending on the charge and feed source. These outside valences or oxygen molecules are not happy in this new arrangement and seek to disengage themselves, creating an abundance of available oxidizing power. Ozone was discovered in 1840 through the process of electrolysis. The development moved about in the laboratory until 1857 when Werner Von Siemans developed a process for general and industrial use of ozone. Experimentation and development continued in the search to improve on the generation of this fragile molecule that does so much, but readily decomposes back to oxygen. There are several ways to produce

ozone—carona discharge, UV light, photo chemical and cold plasma have all been improved by science and technology and the processes are now relatively inexpensive. Ozone, unlike most other chemicals, has no natural resource or method of storage. Ozone is generated onsite, and due to its rapid decomposition, cannot be stored for extended periods of time. The generation method of carona discharge requires the energetic excitement of molecular oxygen to redistribute itself into atomic oxygen in the form of O3. The “silent arc discharge” known also as carona discharge or brush discharge has become the preferred method of ozone generation when outputs above 1 gram per hour are required. A carona discharge generator can take on many forms, sizes and ozone outputs. The required components of a basic carona discharge ozone Water Disinfection 2009

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6focus on ozone generator are: • Two electrodes separated by a gap; • A dielectric material inserted into the gap; • A feed gas flow containing oxygen inserted into the gap; and • Sufficient voltage potential between the two electrodes to cause a current flow through the gas.

Ozone Generation The reliability, performance and efficiency of the ozone generator depend on several factors. Because more than 80% of the applied electrical energy is converted to heat, the materials used in constructing the generator must be heat resistant. The heat generated must also be removed quickly and efficiently from the area or the heat will accelerate the decomposition of the ozone generated. Some ozone generators are watercooled. For small ozone generators, this method can be costly. Another method of cooling is through airflow or refrigeration. With the proper use of airflow, heat is reduced and utility costs are not increased. Many manufacturers use heat-sink devices in their design around the ozone components to direct heat away from the unit. The generation of ozone is a process of balance and equilibrium because ozone is being generated and destroyed concurrently. Feed-gas decontamination is critical for good ozone generation. Heat, particulate matter, moisture, feed-gas flow (volume), pressure, vacuum, water conditions and other variables will affect the ozone quality and percentage of concentration. This is one reason of many that clean dry air or oxygen should be used in the generation of ozone. The U.S. Environmental Protection Agency suggests that minimum moisture content below -60 Dew point (frost point) should be maintained with the feed source. Clean air, free of particulate matter, provides for maximum oxygen content in the volume of air

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being supplied as a feed gas. Dry air, to maximize volume flow, also eliminates the potential for nitrous oxide development when the carona arc energizes the feed gas. Nitrogen oxide, converted to nitric acid, is detrimental to the operating equipment and catalytically destroys the ozone. The selection of the dielectric material is critical in the performance, output and life of the generator. When considering the dielectric, it should be rated based on the continuous electron bombardment necessary to generate the desired ozone output. This same concern must be applied when selecting the electrodes. To provide a sufficient voltage potential between the electrodes to generate the ozone, a transformer is incorporated into the system to step up the voltage and operate between 10,000 and 25,000 volts at low amperage. This voltage can vary based on the design characteristics for the ozone application. Some transformers are of the dry type where others can be encased in oil or filled with silicone or other heat-control material to maintain low operating temperatures. The line voltage to the transformers can be 120 VAC, 230 VAC or 440 VAC in single phase or 3 phase at 50 to 60 Hz. Ozone is a gas that is virtually colorless and has an acidic odor. The gas has an electrochemical oxidation potential that is quite high and is superior to chlorine or other sanitizing products. The high oxidizing potential allows ozone to break down organic compounds that chlorine cannot. The pungent odor makes the presence of ozone immediately noticeable but not necessarily harmful. Most people can detect about 0.01 ppm in the air, well within the general comfort level of individuals. Symptoms that are experienced with concentrations at 0.01 to 1 ppm are headaches, irritation, burning of the eyes or respiratory discomfort. When compared to the same exposure to chlorine, you will find that an exposure to 1,000 ppm of ozone for 30 seconds would be

mildly irritating but the same exposure to chlorine is often fatal. Ozone will attack and decompose organic and inorganic materials. The oxidation of inorganic material helps in the process of treating soluble soil, making it insoluble so that it can be precipitated out of solution. This attribute is the basis for top-end wastewater treatment. Potential ozone applications, at present, seem unlimited. The benefits are untold in environmental issues, economic issues and health benefits. Now that we have produced the ozone, we harness and apply it for practical benefits. One of the simplest ways is to use a venturi injector. This device, set into the stream of water that is in use and to be infused with the ozone, creates a pressure differential from the inlet to the outlet side of the device. This pressure differential creates a low-pressure vacuum in the outlet flow of the water. This vacuum is the suction for the ozone feed line into the water flow. This type of application should be designed properly so that the loss of ozone in the vacuum does not inhibit the designed function of the ozone. The venturi system requires a water flow under pressure. Another method is the use of a sparger, which allows the ozone bubble into the water under pressure for dispersion in the water. This method provides for large and small bubbles of ozone to be applied and allows for off gassing unless destroyed. wd Jack J. Reiff is president of Wet-Tech, The Ozone People. Reiff can be reached at 508.831.4229, or by e-mail at [email protected] For more information related to this article, visit www.wwdmag.com/ lm.cfm/di030901 or www.wqpmag. com/lm.cfm/di030901

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6applications—chlorine

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n 2006, the W.R. Wise Water Treatment Plant in Greenwood, S.C., converted its disinfection system from gaseous chlorine to onsite

generation of sodium hypochlorite (0.8%); from gaseous anhydrous ammonia to commercial aqua ammonia (19%); and from gaseous chlorine and solid sodium chlorite to liquid sodium chlorate and 78% sulfuric acid for onsite generation of chlorine dioxide.

By David Tuck

Conversion from gas to liquid disinfection yields significant improvement in water quality

The use of gaseous chlorine at water treatment plants has, for many years, been an effective method of disinfection. It remains by far the most common method used globally to disinfect water and wastewater and is the most commonly used disinfectant in treatment plants throughout the U.S. The safety of chlorine gas has, however, come under increased scrutiny in recent years. At many plants, minor chlorine gas leaks occasionally occur with faulty valves and poor connections, and the risk for major leaks is always present. At low levels, chlorine gas can cause eye, skin and respiratory irritation, while exposure in high enough doses can be fatal. In addition to the side effects related to chlorine gas exposure, the nature of the gas allows migration to distances well beyond the point of release. In addition, storing, moving, handling and changing the one-ton chlorine gas cylinders are cumbersome and potentially hazardous. The regulatory compliance issues related to chlorine also are significant. The OSHA Process Safety Management Plan, which the Wise Plant was required to maintain, was voluminous. Another regulatory challenge was the U.S. Environmental

Protection Agency’s (EPA) Risk Management Plan, which the plant was required to develop and maintain.

Decision to Convert The decision to undertake the conversion project at the Wise Plant was driven by the result of vulnerability assessment recommendations in 2002. The utility was looking to develop a flexible alternative disinfection strategy throughout the plant that would enable the facility to further ensure operator and community safety, reduce Hazmat and PPE training and meet EPA regulations concerning disinfection byproducts (DBPs)—regulations that no longer allowed the use of free Cl2 as the primary disinfectant. The Wise Plant evaluated several alternative disinfection options including free chlorine, chlorine dioxide, chloramines and ozone. Ultimately, the Wise Plant decided to install a 1,500-lb/day ClorTec onsite sodium hypochlorite generation system from Severn Trent Services. The ClorTec system offers significant benefits over competitive onsite systems— particularly its ability to improve water quality through the reduction of total trihalomethanes and haloacetic acids levels and improvements Water Disinfection 2009

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6applications—chlorine in chloramine levels. The flexibility of the selection paid off immediately as the plant was able to utilize existing space to save costs. The chlorine gas cylinder storage area was used for the sodium hypochlorite storage area and brine tanks. The gas cylinders’ handling area was used to house the new liquid feeders for sodium hypochlorite. Generating sodium hypochlorite on site is a simple and straightforward process that uses three common consumables: salt, water and electricity. The onsite generation system selected by the Wise Plant operates by feeding softened water into a brine dissolver. The salt dissolves to form a brine solution, which is further diluted to the desired salt solution. The salt solution is then passed through electrolytic cell(s), which apply a low-voltage DC current to the brine to produce the sodium hypochlorite. The sodium hypochlorite is then safely stored in three bulk storage tanks. When it reaches the low-level set point, the system

automatically restarts to replenish its supply. Three liquid feeders inject the hypochlorite as needed. In addition to significant improvements in water quality, the use of onsite sodium hypochlorite generation offers several advantages over the use of gaseous chlorine for disinfection. First, the disinfectant is produced and stored in liquid form. The 0.8% solution generated by an onsite system is nonhazardous, eliminating the need for system users to develop and maintain an EPA Risk Management Plan. Hazmat training is not required for handling the disinfectant, and there is no need for the use of self-contained breathing apparatuses with onsite sodium hypochlorite disinfection systems. In addition, onsite systems do not suppress finished water pH to the extent that gaseous chlorine disinfection does; therefore, the amount of pH adjustment chemical (i.e., lime or caustic) necessary before distribution of finished water is reduced. The onsite generation process also

is a cost-effective disinfection alternative. A pound of chlorine equivalent can be generated on site using salt, water and electricity for as low as 20 cents/lb of chlorine equivalent (2006 pricing). Systems typically provide a return on initial investment within three to five years.

Dramatic Reductions, Improvements Once the new disinfection system was online at the Wise Plant, there was a noticeable improvement in water quality, including a dramatic reduction in total trihalomethanes and haloacetic acids levels, improvement of chloramine levels in the distribution system, a reduction in flushing required at dead-ends and savings through the reduced need for post-pH adjustment chemicals. Annual flushing has been reduced by 76% and the flushing process takes less time, equating to a cost savings of $12,688 per year. Post-pH adjustment with lime or caustic has resulted in a reduction of 30 lb-per-mgd, a savings

Onsite sodium hypochlorite generation system

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of $11,436 per year. The Wise Plant used chlorine dioxide as the primary disinfectant, which was key to reducing DBPs prior to coagulation. The 0.8% sodium hypochlorite and chloramines used before and after filtration, respectively, provided more stability in maintaining the chloramine residuals in the distribution system with no additional production of DBPs. The 0.8% hypochlorite is more stable and much easier to feed compared to gaseous chlorine, and less chlorine is lost to the atmosphere because of better mixing and retention in the treated water as compared to gaseous chlorine. The conversion from gas to liquid disinfection at the Wise Plant has proven to be extremely cost-effective. The onsite sodium hypochlorite generation system provides water that is free of pathogens, reducing acute risks; eliminates the production of

DBPs, dramatically reducing chronic risks; and maintains a residual disinfectant in the distribution system for continued pathogen deactivation. In addition to the aforementioned cost savings, the liquid disinfectants are safer and less hazardous to handle. The onsite system is more stable and consistent than the gaseous chlorine system it replaced, all the while reducing the risk for exposure to the staff and community. The 2006 conversion project reflects the Greenwood Commissioners of Public Works’ commitment to delivering superior water quality for its customers. This commitment was acknowledged in 2006 when the utility became only the fourth U.S. water utility ever to receive Phase IV “Excellence in Water Treatment” recognition from the Partnership for Safe Water. The partnership is sponsored by the American Water Works Association, Association

Online Residual Chlorine Monitor

of Metropolitan Water Agencies, Association of State Drinking Water Administrators, EPA, National Association of Water Companies and the American Water Works Association Research Foundation. wd David Tuck is water plant superintendent for Greenwood Commissioners of Public Works. Tuck can be reached at 864.953.2411 or by e-mail at [email protected] For more information related to this article, visit www.wwdmag.com/ lm.cfm/di030902 or www.wqpmag. com/lm.cfm/di030902

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6applications—uv

Solutions for Water Scarcity

T

he Groundwater Replenishment (GWR) system, located in Orange County, Calif., provides purified recycled water for aquifer recharge

and injection into area aquifers to prevent seawater intrusion. The GWR

By Kenny Khoo & Adam Festger

system is a joint project between the Orange County Water District (OCWD) and the Orange County Sanitation District (OCSD). It is the largest indirect potable reuse project of its kind in the world and utilizes the most advanced water treatment technology available.

Treating trace contaminants and disinfecting with UV in water reuse

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FULLSCALE SYSTEM DESIGN PARAMETERS

• • • • • The GWR system treats and reuses wastewater that, in the past, had been discharged to the ocean. The water is reused to provide protection against drought and as a means of achieving a sustainable water supply. The full-scale advanced treatment system takes filtered secondary effluent from the neighboring OCSD treatment plant and converts it to water that exceeds all drinking water quality standards. The 70-milliongal-per-day (mgd) system consists of microfiltration (MF), reverse osmosis (RO) and the TrojanUVPhox UVoxidation/disinfection system.

The UV Solution While MF and RO provide treatment for a variety of organic compounds, there are a number of contaminants that, due to their small molecular size (among other reasons), can pass through even the most advanced RO membranes. Common in wastewater, a compound known as N-nitrosodimethylamine (NDMA) is present at the GWR system as a byproduct formed during upstream wastewater treatment processes. NDMA is formed primarily from the combination of certain precursor chemicals, coagulants and chlorine in wastewater treatment plants. The NDMA molecule is considered to be carcinogenic at very low concentrations and although it passes through MF and RO membranes, it is destroyed with ultraviolet (UV) light by a photochemical process known as UV-photolysis. In addition, using a low concentration (3 parts per million (ppm)) of hydrogen peroxide, the system

initiates an oxidation reaction that destroys other contaminants such as pharmaceuticals or industrial contaminants that have been shown to be present in secondary effluent. Together with the other treatment processes in the GWR system, the TrojanUVPhox creates high-quality water from wastewater that would otherwise be lost to the ocean. The treatment objectives accomplished by the TrojanUVPhox include: • Destruction of nitrosamines and other contaminants treated by UV-photolysis (UV alone); • Destruction of pharmaceuticals, personal care products and industrial chemicals treated by UV-oxidation (UV + hydrogen peroxide); • Microbial disinfection; and • Additional protection—an additional barrier that helps build public confidence in treated water.

• • •

Average flow capacity: 70 mgd Peak flow capacity: 100 mgd Future flow capacity: 130 mgd Design influent NDMA concentration: 150 ppt Target effluent NDMA concentration: 95% at 254 nm Disinfection method: UV

The system consists of the UV reactor system, a hydrogen peroxide storage and metering system and an Optiview UV transmittance monitor. The low-energy TrojanUVPhox minimizes electrical consumption by using high-efficiency amalgam lamps. The system effectively meets the peak flow demand within the design space constraints. It has a footprint comparable to or smaller than the medium-pressure lampbased UV system that was also considered for the project. The water providers of Orange County are proactively meeting the water supply needs of the region, and in doing so, they have garnered public support for the project.

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6applications—uv A key component of their efforts has been the design of a treatment process providing multiple barriers to chemical and microbial contaminants and meets California Dept. of Public Health notification levels for chemicals such as NDMA (notification level of 10 parts per trillion) and 1,4-dioxane (notification level of

3 parts per billion). In order to obtain an operating permit for the UVPhox system, a 5-mgd demonstration system underwent extensive performance testing to demonstrate both NDMA destruction and microbial disinfection. The disinfection capability of the system was determined by

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measuring the log inactivation of MS2 bacteriophage seeded into the influent stream upstream of the UV system. In a similar fashion, its ability to destroy NDMA was determined by measuring the influent and effluent NDMA concentrations. The GWR system design specifications and the 2003 NWRI/ AWWARF UV Guidelines require validation of >100 mJ/cm 2 delivered dose, >4-log inactivation of MS2, and >1.2-log reduction of NDMA.

The performance of the TrojanUVPhox treatment system exceeded DHS performance requirements and OCWD design criteria. The system effectively reduced NDMA to below the 10-ppt treatment level given an influent concentration of 150 ppt. Given an influent concentration of MS2 that allowed demonstration of a 5-log reduction, the system completely eliminated the MS2 bacteria in the effluent, leaving zero plaqueforming units per milliliter (PFU/mL). The dose required to perform this reduction is in excess of 100 mJ/cm2 and was achieved with only a fraction of the total system in operation. wd Kenny Khoo is municipal market specialist for Trojan Technologies. Khoo can be reached by e-mail at [email protected] Adam Festger is marketing manager, drinking water/environmental contaminant treatment, for Trojan Technologies. Festger can be reached by e-mail at [email protected] For more information related to this article, visit www.wwdmag.com/ lm.cfm/di030903 or www.wqpmag. com/lm.cfm/di030903

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6tech update

Technology01101010

Advancing By Adam Donnellan

I

n the early 1900s, it was discovered that ultraviolet (UV) light had the ability to inactivate microorganisms. Testing showed that waterborne

pathogens—disease-causing microorganisms—were inactivated when exposed to UV radiation. While this discovery remained unused due to the availability of lower cost chemicals, UV has been effectively applied in wastewater plants for the last 30 years.

Disinfecting residential wastewater with UV

Health concerns related to the use of chemicals in water are leading more engineers and system designers to investigate how UV can be used in place of or combined with traditional chemicals. Today, UV light is being used for municipal wastewater, drinking water, industrial process waters and a host of other applications. A recent industry trend has been the use of UV technology to treat residential wastewater.

How the Technology Works For disinfection purposes, inactivation of microorganisms is carried out by a UV lamp’s UV-C light output, which targets the nucleic acids (DNA and RNA) of microorganisms. Exposure to UV-C light prevents the DNA and RNA from replicating; therefore, the microorganism is

prevented from reproducing. Cells that cannot reproduce cannot infect and are therefore harmless. The actual lamps are housed in quartz sleeves, which are in turn housed in a disinfection chamber or vessel. These sleeves not only help maintain maximum operating temperatures but also prevent the lamps from coming in contact with the wastewater. A quartz sleeve looks like glass but unlike glass, it lets the UV-C rays out. While in the vessel, the wastewater is exposed to doses of UV energy. Simply put, UV dose is equal to lamp intensity multiplied by residence time. It is usually represented in microwatt seconds per square centimeter (mWs/cm 2). Time is calculated as the hydraulic residence time in the UV system. The intensity is a function of

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6tech update

Left: Quartz sleeve with a manual wiper system. Top: PVC disinfection vessels with manual cleaning systems.

the lamp type, the arrangement of lamps and the energy-absorbing elements in the water that absorb or interfere with light before it reaches the targeted microorganism. The measurement of absorbing material is referred to as UV transmission (UVT). This is expressed as a percentage from 0 to 100—most wastewater plants average 65%. There are many advantages to this type of disinfection, such as no need for toxic and expensive chemicals; fast treatment; low maintenance and simple and extremely low-cost operation. Because the UV disinfection process does not add chemicals or change the physical or chemical

properties of the effluent, the wastewater is ready for discharge when it leaves the system.

Residential UV Systems Most residential wastewater treatment systems require components that are both rugged and easily maintained. For UV systems in this environment, PVC construction fits the bill. PVC chambers are good for the harsh wastewater and the physical environment and provide a good alternative to traditional stainless steel systems. Because most residential wastewater treatment equipment already uses PVC piping, the UV systems are easy to install.

Table. Accepted dosages for corresponding wastewater discharge permits 15 mJ/cm2 30 mJ/cm2 45 mJ/cm2 60 to 80 mJ/cm2 100 mJ/cm2

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1,000 fecal coliform (FC)/100 mL 200 FC /100 mL 125 FC/100 mL 23 FC/100 mL 0 to 2.2 FC/100 mL reuse

As with any UV disinfection system, maintenance is a prime concern. The system must be accessible for maintenance. This includes a yearly lamp change but more importantly, periodic quartz sleeve maintenance. Due to the heat of the lamp and impurities in the wastewater, the protective quartz sleeves can become fouled. In order to prevent this fouling or build up, a quartz cleaning system must be implemented. This task can be accomplished with a simple manual cleaning mechanism. Using the plunger mechanism, the end user or maintenance operator can wipe the sleeves. The mechanism is comprised of a rod with a handle and a number of bushings housing wiper rings. By plunging the wiper mechanism back and forth over the sleeves, the operator is able to remove debris and other build up. Once cleaned, more UV light will get through the sleeves and into the wastewater. In order for the system to be effective, this maintenance must be done on a regularly scheduled basis.

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System Design In order to meet regulations or discharge permits, the system needs to be properly sized. To size a system, the following must be understood: • Physical location for installation (environment); • Flow rates (peak instant, average and length of periods of no flow); • Physical size of the piping in the rest of the system; • Understanding of how and who will maintain the system; • Determining the discharge permit, which is expressed as a certain number of microorganisms per 100 mL sample; and • Transmission of the wastewater (55% is low, 65% is average, 70% is found with filtration and 85% can be attained through membranes).

Once the numbers are obtained, they can be put into a calculation. The calculation used is called the EPA Point Source Summation Method, as outlined in the 1986 U.S. Environmental Protection Agency design manual. These numbers are generally supported through biological testing, which is referred to as a bioassay. Bioassays can be performed in the lab, in the field and at testing facilities around the world. End users now have the option to integrate a green technology for disinfecting their residential wastewater. While very effective, a proper maintenance plan is the key to success. wd

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Adam Donnellan is director of technical sales, UV products, for Siemens Water Technologies Corp. Donnellan can be reached by e-mail at [email protected] For more information related to this article, visit www.wwdmag.com/ lm.cfm/di030904 or www.wqpmag. com/lm.cfm/di030904

WEB resources hhh Related search terms from www.waterinfolink.com: UV, disinfection, residential

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6focus on uv

how effective is that

UV System? W

hen a homeowner decides to purchase water treatment equipment, they are looking to protect their drinking water and the health

of their family members who are consuming it. They are looking for water confidence, which is an investment into their home similar to installing a new furnace or replacing the windows, but with water treatment the target is family health.

The purchase of water treatment equipment is traditionally done by consumers who are on private water systems, whether surface water or a private well. The trend is starting to shift, however. Consumers that receive water from a municipal supply are now looking for added security by taking some of the water treatment into their own hands.

Either way, the tap can be turned on with the peace of mind that the water is safe to consume. Water treatment can be done in many forms, whether it is with a water softener to remove hardness, a reverse osmosis system to remove dissolved solids, an ultraviolet (UV) system for the destruction of microorganisms or a simple carbon filter to improve the

By Melissa Lubitz

The disinfection ability of a UV system depends on proper lamp maintenance 16

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taste and odor of the water. Regardless of the equipment, all systems must be maintained or they will no longer be effective and can, in some cases, make the water worse. This especially is the case with UV systems. A UV system targets microorganisms, which can cause serious health concerns if not addressed. UV systems must be maintained at least once a year or more, depending on the water quality. This involves the inspection of the quartz sleeve and the replacement of the UV lamp. Both are very important for the UV system to be effective against potential waterborne illness. UV systems are designed for a specific flow rate based on the reactor size, the water quality and the amount of intensity coming

off the UV lamp. Each UV system, regardless of the manufacturer, is designed around a specific lamp technology. Not all UV systems are the same—they are matched with a specific UV system design. Therefore, if a UV system is rated for 10 gpm at 95% UV transmittance, the water will receive sufficient disinfection at that flow rate based on the system design and the UV lamp.

The Brain of the System The UV lamp can be considered the brain of a UV system. Without the UV lamp and quartz sleeve, disinfection cannot occur. All maintenance issues of a UV system are surrounded around the lamp and quartz sleeve being protected. The quartz sleeve must be cleaned in order to ensure that the UV intensity from

the lamp can get to the water and the lamp must be replaced after one year because the UV intensity does drop off over time. With all of these factors in mind, it becomes obvious how important it is that the correct lamp is used within the UV system. The quartz sleeve is also an important component because it protects the lamp. Both the lamp and sleeve are manufactured from a very specific material that readily transmits UV light. Neither the lamp or the quartz sleeve is manufactured simply from glass but a type of quartz that allows the UV system to perform efficiently and protect the water.

Consumer Confidence Consumers considering purchasing a UV system are also buying

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6focus on uv water confidence. In order to ensure that confidence, the correct replacement lamp is vital to the continued performance of that piece of equipment. That being said, if a specific model is purchased, it is imperative that the lamp is replaced with one that has been designed for that model. Otherwise it can be unclear if the UV system is actually disinfecting the water. There are companies in the water industry that are selling knock-off lamps for residential UV systems that are sold throughout the world. These lamps are offered at a very low price with the promise that they operate the same as the UV manufacturer’s lamps, but this is not true. If a consumer were to install a knock-off lamp, the water confidence that was offered by the UV manufacturer no longer holds true and cannot be supported by the manufacturer. As a UV manufacturer, the comments that have been received from the field with regards to how these knock-off lamps are made and how they are performing have been quite alarming: 1. Lamp wiring is inferior as well as incorrect. System operation and safety is then compromised. 2. False indication that lamp is ‘On.’ The knock-off lamps cause a false “Lamp OK” status when

in fact the lamp has not been lit and therefore is not producing any UV light. There will be absolutely no disinfection provided under these conditions. 3. Wrong lamp pin lengths or weak pins. Relates to safety, potential fire hazard and possible damage to the lamp connector, which in turn can destroy the ballast. 4. Certification. By using a knockoff lamp as a replacement, any certifications that the UV system holds will now be voided, such as NSF Standard 55, CSA/UL/CE. In Canada, it is a requirement to have UL/CSA on systems that are sold. If a knock-off lamp that has not been part of this certification is used, the electrical code that is required on newly sold appliances is no longer being met. 5. Insurance. If a fire occurs due to the installation of a knock-off lamp, there may be complications with regards to home insurance as the knock-off lamp voids all electrical certifications. 6. Loss of warranty coverage. UV manufacturers cannot offer any warranty coverage of systems that are not using replacement lamps provided by the manufacturer because they cannot guarantee the safety of the system.

For consumers who invest money into a disinfection treatment device, it is important that the system is maintained as needed in order to keep the water safe. If you are unsure about a lamp, call the manufacturer and they will be able to tell you immediately if you have the appropriate lamp. Be on the lookout for programs that are set up by the manufacturer specifically for this type of situation—they will be prepared for your questions. This is a simple way to ensure that your customer’s water is safe. wd Melissa Lubitz is technical salesperson, municipal projects group, for R-Can Environmental, Inc., a Trojan Technologies Co. Lubitz can be reached by e-mail at [email protected] For more information related to this article, visit www.wwdmag.com/ lm.cfm/di030905 or www.wqpmag. com/lm.cfm/di030905

WEB resources hhh Related search terms from www.waterinfolink.com: UV lamp, disinfection

”In order to ensure water confidence, the correct UV replacement lamp is vital to the continued performance of that piece of equipment.” 18

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Fact:

arch for “tank” se t e rn te In l ra e n A ge 70 million 5 d n a 0 0 2 n e e returns betw irrelevant to re a h ic h w f o st o results–m ter industry.* a w e st a w d n a r te the wa h delivers just rc a se m o .c k in L fo A WaterIn information r– fo g in k o lo e ’r u what yo nd wastewater a r te a w e th to c specifi remaining e th s ze ri o g te ca industry–and f use. results for ease o

Compile the information you need with accuracy and speed With search results compiled from published articles, journals, white papers, supplier sites, association news, product guides and regulatory news, you can have confidence in the quality of the information. WaterInfoLink.com is free and easy to use, with no registration required. *Google™ and Yahoo® searches conducted on “tank” Sept. 10, 2008.

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