Chlorination of Drinking Water

Embed Size (px)

Citation preview

  • 8/10/2019 Chlorination of Drinking Water

    1/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    Chlorination of Drinking WaterWritten by Mr. Brian Oram, PG

    Chlorination of Drinking Water - Private Well Owner Guide

    Commercial System

    Water used for drinking and cooking should be free of pathogenic (disease causing)

    microorganisms that cause such illnesses as typhoid fever, dysentery, cholera, and gastroenteritis.

    Whether a person contracts these diseases from water depends on the type ofpathogen, the

    number of organisms in the water (density), the strength of the organism (virulence), the volume ofwater ingested, and the susceptibility of the individual. Purification of drinking water containing

    pathogenic microorganisms requires specific treatment called disinfection.

    Although several methods eliminate disease-causing microorganisms in water, chlorination is the

    most commonly used. Chlorination is effective against many pathogenic bacteria, but at normal

    dosage rates it does not kill all viruses, cysts, or worms. When combined with filtration, chlorination

    is an excellent way to disinfect drinking water supplies.

    This fact sheet discusses the requirements of a disinfection system, how to test the biological

    quality of drinking water, how to calculate the amount of chlorine needed in a particular situation,

    chlorination equipment, by-products of disinfection, and alternative disinfection methods.

    Disinfection requirements

    Disinfection reduces pathogenic microorganisms in water to levels designated safe by public

    health standards. This prevents the transmission of disease.

    An effective disinfection system kills or neutralizes all pathogens in the water. It is automatic,

    simply maintained, safe, and inexpensive. An ideal system treats all the water and provides

    residual (long term) disinfection. Chemicals should be easily stored and not make the water

    unpalatable.

    Join Our Newsletter

    Sign Up to Receive

    Our FREE Newsletter for

    the Latest News & Information

    New Booklet

    PA Guide to

    Drinking Water

    (2012) 2nd Edition

    & Free PDF Version

    of the First Edition

    Support

    Support this Portal and Outreach

    Like This Portal $5.00 USD

    Water Research Center

    Contact

    About

    Surveys

    PA Private Well Owners

    Individuals Outside of PA

    About Reports Standards Glossary Help Search Contact

    Water Testing Water Treatment Link

    http://www.water-research.net/http://www.water-research.net/http://www.water-research.net/index.php/linkshttp://www.water-research.net/http://www.water-research.net/index.php/glossaryhttp://www.water-research.net/index.php/helphttp://www.water-research.net/index.php/searchmailto:[email protected]?subject=contactushttps://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067http://www.water-research.net/searchsite.htmhttp://www.water-research.net/index.php/linkshttp://www.water-research.net/mailto:[email protected]?subject=contactushttp://www.water-research.net/index.php/searchhttp://www.water-research.net/index.php/helphttp://www.water-research.net/index.php/glossaryhttp://www.surveymonkey.com/s/privatewellhttp://www.surveymonkey.com/s/NMG6RQ3http://www.water-research.net/index.php/about/water-research-centermailto:[email protected]?subject=contactushttp://www.water-research.net/index.php/private-well-owner-booklethttp://www.water-research.net/index.php/join-our-newsletterhttp://www.water-research.net/searchsite.htmhttps://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067
  • 8/10/2019 Chlorination of Drinking Water

    2/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    State and federal governments require public water supplies to be biologically safe. The U.S.

    Environmental Protection Agency (EPA) recently proposed expanded regulations to increase the

    protection provided by public water systems. Water supply operators will be directed to disinfect

    and, if necessary, filter the water to prevent contamination from Giardia lamblia, coliform bacteria,

    viruses, heterotrophic bacteria, turbidi ty, and Legionella.

    Private systems, while not federally regulated, also are vulnerable to biological contamination from

    sewage, improper well construction, and poor-quality water sources. Since more than 30 million

    people in the United States rely on private wells for drinking water, maintaining biologically safe

    water is a major concern.

    Testing water for biological quality

    The biological quality of drinking water is determined by tests for coliform group bacteria. These

    organisms are found in the intestinal tract of warm-blooded animals and in soil. Their presence in

    water indicates pathogenic contamination, but they are not considered to be pathogens. The

    standard for coliform bacteria in drinking water is "less than 1 coliform colony per 100 milliliters of

    sample" (< 1/ 100ml).

    Public water systems are required to test regularly for coliform bacteria. Private system testing is

    done at the owner's discretion. Drinking water from a private system should be tested for

    biological quality at least once each year, usually in the spring. Testing is also recommended

    following repair or improvements in the well.

    Coliform presence ina water sample does not necessarily mean that the water is hazardous to

    drink. The test is a screening technique, and a positive result (more than 1 colony per 100 ml water

    sample) means the water should be retested. The retested sample should be analyzed for fecal

    coliform organisms. A high positive test result, however, indicates substantial contamination

    requiring prompt action. Such water should not be consumed until the source of contamination is

    determined and the water purified.

    A testing laboratory provides specific sampling instructions and containers. The sampling

    protocol includes the following:

    run cold water for a few minutes (15 minutes) to clear the lines;

    upon collecting sample, immediately cap bottle and place in chilled container if delivery to lab

    exceeds 1 hour (never exceed 30 hours). Many laboratories do not accept samples on Friday due

    to time limits.

    use sterile sample container and handle only the outside of container and cap;

    Chlorine treatment

    Chlorine readily combines with chemicals dissolved in water, microorganisms, small animals,

    plant material, tastes, odors, and colors. These components "use up" chlorine and comprise the

    chlorine demand of the treatment system. It is important to add sufficient chlorine to the water to

    meet the chlorine demand and provide residual disinfection.

    The chlorine that does not combine with other components in the water is free (residual) chlorine,

    and the breakpoint is the point at which free chlorine is available for continuous disinfection. An

    ideal system supplies free chlorine at a concentration of 0.3-0.5 mg/l. Simple test kits, most

    Resources

    Water Library

    Watershed

    Water Quality by State

    Is My Drinking Water Safe?

    Growing Greener Program

    Powerpoint Presentations

    Undergraduate Tools

    School Projects

    ...In Drinking Water

    Arsenic

    Bacteria

    Barium

    Corrosive Water

    Hardness

    Iron

    Lead

    Lithium

    Manganese

    Methane

    Nitrate & Nitrite

    Radiological Contaminants

    Radon

    Sulfur

    Taste & Odor

    http://www.water-research.net/index.php/taste-odorhttp://www.water-research.net/index.php/sulfurhttp://www.water-research.net/index.php/radonhttp://www.water-research.net/index.php/radiological-contaminantshttp://www.water-research.net/index.php/nitratehttp://www.water-research.net/index.php/methanehttp://www.water-research.net/index.php/manganesehttp://www.water-research.net/index.php/lithiumhttp://www.water-research.net/index.php/leadhttp://www.water-research.net/index.php/ironhttp://www.water-research.net/index.php/hardnesshttp://www.water-research.net/index.php/corrosive-waterhttp://www.water-research.net/index.php/bariumhttp://www.water-research.net/index.php/bacteriahttp://www.water-research.net/index.php/arsenic1http://www.water-research.net/index.php/school-projectshttp://www.water-research.net/index.php/undergraduate-toolshttp://www.water-research.net/index.php/powerpoint-presentationshttp://www.water-research.net/index.php/growing-greener-programhttp://www.water-research.net/index.php/is-my-drinking-water-safehttp://www.water-research.net/index.php/water-quality-by-statehttp://www.water-research.net/index.php/watershedhttp://www.water-research.net/index.php/water-library
  • 8/10/2019 Chlorination of Drinking Water

    3/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    commonly the DPD colorimetric test kit (so called because diethyl phenylene diamine produces

    the color reaction), are available for testing breakpoint and chlorine residual in private systems.

    The kit must test free chlorine, not total chlorine.

    Contact time with microorganisms

    The contact (retention) time (Table 1) in chlorination is that period between introduction of the

    disinfectant and when the water is used. A long interaction between chlorine and the

    microorganisms results in an effective disinfection process. Contact time varies with chlorine

    concentration, the type of pathogens present, pH, and temperature of the water. The calculation

    procedure is given below.

    Contact time must increase under conditions of low water temperature or high pH (alkalinity).

    Complete mixing of chlorine and water is necessary, and often a holding tank is needed to achieve

    appropriate contact time. In a private well system, the minimum-size holding tank is determined by

    multiplying the capacity of the pump by 10. For example, a 5-gallons-per-minute (gpm) pump

    requires a 50-gallon holding tank. Pressure tanks are not recommended for this purpose since

    they usually have a combined inlet/outlet and all the water does not pass through the tank.

    An alternative to the holding tank is a long length of coiled pipe to increase contact between water

    and chlorine. Scaling and sediment build-up inside the pipe make this method inferior to the

    holding tank.

    Table 1. Calculating Contact Time

    minutes required = K / chlorine residual (mg/l)

    K values to determine chlorine contact time

    Highest

    Lowest Water Temperature (degrees F)

    pH > 50 45 < 40

    6.5 4 5 6

    7.0 8 10 12

    7.5 12 15 18

    8.0 16 20 24

    8.5 20 25 30

    9.0 24 30 36

    Find us on Facebook

    National Water Tests Water

    Research Watershed Center

    Citizen Science

    128 people like National Water Tests Water Research

    Watershed Center Citizen Science.

    Like

    National Water Tests

    Water Research

    Watershed Center Citizen

    Science

    Yesterday at 03:22

    Maryland - I thought I was away from Oil

    and Gas Issues.

    http://www.cardin.senate.gov/newsroom/

    press/release/cardin-opposes-seismic-

    testing-off-mid-atlantic-coast

    National Water Tests

    Water Research

    Watershed Center Citizen

    Science

    RT @sarmje: RT @KevinOnWater: Utility Offers

    Free Treated #WastewaterTo Residential

    Customers ow.ly/zFT9h#waterreuse#recycling

    Retweeted by BrianOram

    NACWA

    @NACWA

    Expand

    @karen_langley@WPXIJoeHoldenAll elected

    officials and state employees should be able to

    justify their salaries with documentation

    BrianOram

    @PACleanwater

    Expand

    @amy_galfordIf you got any cell phones-

    BrianOram

    @PACleanwater

    30 Jul

    2 Aug

    2 Aug

    Tweets Follow

    Tweet to @PACleanwater

    https://twitter.com/intent/tweet?screen_name=PACleanwaterhttps://twitter.com/PACleanwaterhttps://twitter.com/PACleanwaterhttps://twitter.com/PACleanwater/statuses/495296181170626561https://twitter.com/PACleanwater/statuses/495296942155759616https://twitter.com/NACWA/statuses/494184376469438464https://twitter.com/PACleanwaterhttps://twitter.com/amy_galfordhttps://twitter.com/PACleanwater/statuses/495296942155759616https://twitter.com/PACleanwaterhttps://twitter.com/WPXIJoeHoldenhttps://twitter.com/karen_langleyhttps://twitter.com/NACWA/statuses/494184376469438464https://twitter.com/NACWAhttps://twitter.com/PACleanwaterhttps://twitter.com/hashtag/recycling?src=hashhttps://twitter.com/hashtag/waterreuse?src=hashhttp://t.co/WzU2S8ghW1https://twitter.com/hashtag/Wastewater?src=hashhttps://twitter.com/KevinOnWaterhttps://twitter.com/sarmjehttps://www.facebook.com/isa.kokihttps://www.facebook.com/jilbin.georgehttps://www.facebook.com/winnie.kansiimehttps://www.facebook.com/dan.owens.18https://www.facebook.com/ryan.billings.549https://www.facebook.com/jilalu.hussenhttps://www.facebook.com/yaghub.tahaeihttps://www.facebook.com/laxmilal.menariya.374https://www.facebook.com/ayman.alrehailihttps://www.facebook.com/srdominguez716https://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067?ref=streamhttps://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067?ref=stream&fref=nfhttps://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067?ref=streamhttp://l.facebook.com/l.php?u=http%3A%2F%2Fwww.cardin.senate.gov%2Fnewsroom%2Fpress%2Frelease%2Fcardin-opposes-seismic-testing-off-mid-atlantic-coast&h=NAQGk-YRp&enc=AZP8ow9VHRfE4lgVhUUsOkqB3OjG-gec5jumD7qO0YKYEMcm8l-CbQ4BuQ7OWRkZ_m5Juf_Ws1A5dULavl5uQvDXhjtnZOsIDjwjpmycRLIEPIbv9e3ViEwXKheRMIfKccnATfn820UUfDacmljl2KtjYFURoIV7O0EDWc8OOIeKSQ&s=1https://www.facebook.com/permalink.php?story_fbid=746951415363327&id=133630743362067https://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067?ref=stream&fref=nfhttps://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067https://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067https://www.facebook.com/pages/National-Water-Tests-Water-Research-Watershed-Center-Citizen-Science/133630743362067
  • 8/10/2019 Chlorination of Drinking Water

    4/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    To calculate contact time, one should use the highest pH and lowest water temperature

    expected. For example, if the highest pH anticipated is 7.5 and the lowest water temperature is

    42 F, the "K" value (from the table below) to use in the formula is 15. Therefore, a chlorine

    residual of 0.5 mg/l necessitates 30 minutes contact time. A residual of 0.3 mg/l requires 50

    minutes contact time for adequate disinfection.

    Chlorination levels

    If a system does not allow adequate contact time with normal dosages of chlorine,

    superchlorination followed by dechlorination (chlorine removal) may be necessary.

    Superchlorination provides a chlorine residual of 3.0-5.0 mg/l, 10 times the recommended

    minimum breakpoint chlorine concentration. Retention time for superchlorination is approximately

    5 minutes. Activated carbon filtration removes the high chlorine residual .

    Shock chlorination is recommended whenever a well is new, repaired, or found to be

    contaminated. This treatment introduces high levels of chlorine to the water. Unlike

    superchlorination, shock chlorination is a "one time only" occurrence, and chlorine is depleted as

    water flows through the system; activated carbon treatment is not required. If bacteriological

    problems persist following shock chlorination, the system should be evaluated. More information

    regarding shock disinfection can be found at Shock Well Disinfection Website.

    CHLORINATION GUIDELINES

    Chlorine solutions lose strength while standing or when exposed to air or sunlight. Make fresh

    solutions frequently to maintain necessary residual.

    Maintain a free chlorine residual of 0.3-0.5 mg/l after a 10 minute contact time. Measure the

    residual frequently.

    Once the chlorine dosage is increased to meet greater demand, do not decrease it.

    Locate and eliminate the source of contamination to avoid continuous chlorination. If a water

    source is available that does not require disinfection, use it.

    Keep records of pertinent information concerning the chlorination system.

    Types of chlorine used in disinfection

    Public water systems use chlorine in the gaseous form, which is considered too dangerous and

    expensive for home use. Private systems use liquid chlorine (sodium hypochlorite) or dry chlorine

    (calcium hypochlorite). To avoid hardness deposits on equipment, manufacturers recommend

    using soft, distilled, or demineralized water when making up chlorine solutions.

    Liquid Chlorine

    household bleach most common form

    available chlorine range:

    Dry Chlorine

    powder dissolved in water

    available chlorine: 4%

    http://www.water-research.net/shockwelldisinfection.htm
  • 8/10/2019 Chlorination of Drinking Water

    5/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    5.25% (domestic laundry bleach)

    18% (commercial laundry bleach)

    slightly more stable than solutions from dry

    chlorine

    protect from sun, air, and heat

    produces heavy sediment that clogs

    equipment; filtration required

    dry powder stable when stored properly

    dry powder fire hazard near flammable

    materials

    solution maintains strength for 1 week

    protect from sun and heat

    Equipment for continuous chlorination

    Continuous chlorination of a private water supply can be done by various methods. The injection

    device should operate only when water is being pumped, and the water pump should shut off if the

    chlorinator fails or if the chlorine supply is depleted. A brief description of common chlorination

    devices follows.

    chlorine pump(see Fig. 1):

    commonly used, positive displacement or chemical-feed device,

    adds small amount, of chlorine to the water,

    dose either fixed or varies with water flow ratesrecommended for low and fluctuating water pressure,

    chlorine drawn into device then pumped to water delivery line

    Figure 1. Pump type (positive displacement) chlorinator

    Figure 2. Injector (aspirator) chlorinator

    suction device:

    line from chlorine supply to suction side of water pump,

    chlorine drawn into water held in well pump,

    dosage uniformity not assured with this system,

    some suction devices inject chlorine directly into well water, increasing contact time between

  • 8/10/2019 Chlorination of Drinking Water

    6/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    More information about

    the Water Research Center:

    Attn: Mr. Brian Oram, Professional Geologist (PG)

    ater Research Center

    B.F. Environmental Consultants Inc.

    Technology Outreach Program | Available Test Parameters

    Research Interests, Funded Research & Applied Research | Homeowner Water Testing

    Environmental Topics - Infiltration, Permeability, Soil Science, Wellhead Protection,

    Groundwater, Watersheds PowerPoint Presentations

    microorganisms and disinfectant; water/chlorine mixture is then drawn into well pump

    aspirator(see Fig. 2):

    simple, inexpensive mechanism,

    requires no electricity,

    vacuum created by water flowing through a tube draws chlorine into a tank where it mixes with

    untreated water,

    treated solution fed into water system,

    chlorine doses not consistently accurate

    solid feed unit:

    waste treatment and swimming pool disinfection,

    requires no electricity,

    controlled by flow meter,

    device slowly dissolves chlorine tablets to provide continuous supply of chlorine solution

    batch disinfection:

    used for fluctuating chlorine demand,

    three tanks, each holding 2 to 3 days' water supply, alternately filled, treated, and used

    Disinfection by-products

    Trihalomethanes (THMS)are chemicals that are formed, primarily in surface water, when

    naturally occurring organic materials (humic and fulvic acids from degradation of plant material)

    combine with free chlorine. Some of the THMs present in drinking water are chloroform,

    bromoform, and bromodichloromethane. Since groundwater rarely has high levels of humic and

    fulvic acids, chlorinated private wells contain much lower levels of these chemicals.

    THMs are linked to increases in some cancers, but the potential for human exposure to THMs from

    drinking water varies with season, contact time, water temperature, pH, water chemistry and

    disinfection method. Although there is a risk from consuming THMs in chlorinated drinking water,

    the health hazards of undisinfected water are much greater. The primary standard (maximum

    contaminant level) for total THMs in drinking water is 0.10 mg/l, and activated carbon filtration

    removes THMs from water.

    Other Outside Links

    Water Treatment Systems- Residential and Commercial

    Certified Water Testing Services

    http://www.webdesignpros.net/watertesting/certifiedwatertesting.htmhttp://www.webdesignpros.net/watertreatment/watertreatment.htmhttp://www.water-research.net/trihalomethanes.htmhttp://www.water-research.net/powerpoint/index.htmhttp://www.water-research.net/watertesting.htmhttp://www.water-research.net/Experience.htmhttp://www.water-research.net/Inorganic_Testing.htmhttp://www.water-research.net/TTP_Program.htmhttp://www.water-research.net/
  • 8/10/2019 Chlorination of Drinking Water

    7/7

    8/3/2014 Chlorination of Drinking Water

    http://www.water-research.net/index.php/water-treatment/tools/chlorination-of-water

    15 Hillcrest Drive, Dallas, PA 18612

    Links Help Guides Search Our Site

    About Contact

    Continuing Education Courses:

    OSHA Training, Engineers, Geologists, Sustainability,Architects, LEED Professionals

    Watershed Monitoring, Research, Training, Lake and Watershed Studies,

    Citizen Monitoring, Volunteer Monitoring Programs

    The Water Library - Pdf files on Water Issues & Topics

    Tools for Environmental Professionals, Citizens, & Students

    Field Training & Workshops in Earth Science | Affiliations & Hot Links

    2014 Water Research Watershed Center. All Rights Reserved. | Site Design by Resource Media

    http://www.water-research.net/links.htmhttp://www.water-research.net/infiltrationbmp.htmhttp://www.water-research.net/schoolprojects/schoolprojects.htmhttp://www.water-research.net/Waterlibrary/index.htmhttp://www.water-research.net/Watershed/https://webdesignpros.redvector.com/LMS.Web/Dashboard/VAR-Course-Details.aspx?id=ca51a4c3-cdb2-48a8-b2fb-f57eaf0b3d63&lp=R7%2fLkjoG8F8%3d&hours=30.00&backnavkey=VAR_CART_CATALOGhttp://www.bfenvironmental.com/GreenBuild.phphttp://www.bfenvironmental.com/sustain.phphttp://www.bfenvironmental.com/workshops.phphttp://www.bfenvironmental.com/engineers.phphttp://www.bfenvironmental.com/training.phphttp://www.bfenvironmental.com/http://www.water-research.net/index.php?Itemid=261http://www.water-research.net/index.php/abouthttp://www.water-research.net/index.php/searchhttp://www.water-research.net/index.php/helphttp://www.water-research.net/index.php/links