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Chlorination by Muhammad Fahad Ansari 12IEEM14
 

Chlorination by Muhammad Fahad Ansari 12IEEM14

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Muhammad Fahad Ansari 12IEEM14

Muhammad Fahad Ansari 12IEEM14

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  • Identify my colleagues in the audience
  • Identify my colleagues in the audience
  • We are all in the business of protecting public health through prevention. Safe drinking water does not happen by itself, but rather by the deliberate actions of men and women responsible for water system planning, design, management, operations, and maintenance. Describe the importance of attending to both the physical infrastructure and the human infrastructure behind safe drinking water.
  • Group A sources only Number of ACTIVE GROUP A water systems: 4,184 Number of ACTIVE, PRIMARY or SEASONAL Sources: 8,321 Review for all ACTIVE, PRIMARY or SEASONAL (not emergency) sources that provides any or all treatment that would Chlorinate. (CHLORAMINES, CHLORINATION, GASEOUS, CHLORINATION, HYPOCHLORITE, CHLORINE DIOXIDE, HYPOCHLORINATION, EROSION / TABLETS, HYPOCHLORINATION, ON-SITE GENERATOR, HYPOCHLORITE SOLUTION) There are 4,176 (50.2%) sources that meet this definition. When you take out duplication of sources with treatments and duplication from number of multiple sources per system you find there are 1832 (43.8%) ACTIVE GROUP A systems that have one or more sources that meet the above criteria. 659/1705 (39%) Group A ACTIVE COMMUNITY SYSTEMS 1 to 200 RESIDENTIAL CONNECTIONS that CHLORINATE/TOTAL Group A ACTIVE COMMUNITY SYSTEMS 1 to 200 RESIDENTIAL CONNECTIONS.
  • 82% of WA state residents supplied by Group A water systems are supplied by chlorinated water. Consistent with national average. The Residential Population of ALL Active Group A Water Systems: 5,545,000 The Residential Population of Active Grp A Systems w/ Chlorination : 4,496,000 (81.8%)
  • MAJOR THEMES OF CHLORINATION MECHANICS: The chlorine disinfectant process – what works and what doesn’t Chlorine chemistry – what happens when chlorine hits the water Chlorine byproducts and human health Killing an organism versus inactivating an organism. Identify three groups of pathogens: Bacteria, virus, and protozoa. Disinfection kinetics in cells: Disruption of protein synthesis Destruction of enzymes. Leading to disrupted metabolism Disinfection kinetics in viruses: Affinity for combining with nitrogen in the viral DNA, breaking nitrogen bonds and disabling replication (“inactivation”) How effective is UV (order of effectiveness, from most effective to least): Giardia and Crypto 10 mJ/cm 2 dose needed for a given level of inactivation Bacteria 15 mJ/cm 2 Most virus 40 mJ/cm 2 Adenovirus (standard) 186 mJ/cm 2
  • Disinfection is a PROCESS. It is not instantaneous. Reduced “potency” with increasing pH, decreasing water temperature, increasing turbidity, insufficient mixing, and increasing chlorine demand. Other chlorine demanding compounds: various organic and inorganic compounds Walkerton =- Limestone geology suggests higher pH – diminished “potency”. The concept of disinfection as a process has gone commercial: describe disinfectant wipe container information
  • Talked about disinfection as a process. CT concept reflects this. CT concept applies mainly to the inactivation of viruses and Giardia , Inactivation of bacteria is achieved when the treatment standard for virus inactivation is met. DOH and EPA regulations state that groundwater under normal conditions of temperature and pH require a CT of 6 to meet the virus and bacteria inactivation requirement (99.99%). 1 For flow in pipelines, T reflects full volume of the pipe. Example: 6-inch pipeline - 1.5 gallons of water per foot - 1000-feet long Pipeline holds about 1500 gallons. If peak flow through the pipeline is 100 gallons per minute, then T = 15 minutes. If chlorine residual at the end of the 1000-foot pipeline is 0.4 ppm, then CT = 15 x 0.4 = 6. Sufficient to meet virus inactivation requirement for groundwater.   In order to achieve a similar level of inactivation for Giardia, surface water with a pH of 7 (neutral) and temperature of ~40 F requires a CT value of about 200. Refer to previous slide (order of effectiveness). 1. Studies have shown some virus are more resistant, and may require CT greater than 400 to achieve 99.99% inactivation. (Virus survival studies have also been conducted on a variety of both laboratory and field strains (AWWA, 1979).)
  • Free chlorine is the most effective form of chlorine. Combined chlorine is a very weak disinfectant , and not considered a primary disinfectant. MCL for free and total chlorine is 4.0 mg/l. Regulations call for “detectable” chlorine residual. DOH recommends 0.2 mg/l FREE chlorine. In swimming pools, nitrogen sources include urine, skin oils and perspiration, and cosmetics and sunscreen.
  • What happens when chlorine gas or hypochlorite enters the water: Produces hypochlorous acid and hypochlorite ion oxidizes organics and inorganics in solution changes pH (up with hypochlorite and down with chlorine gas) produces chlorinated byproducts when combined with natural organic matter produces chloramines when ammonia or organic nitrogen is present. Two species of free chlorine: HOCl and OCl. OCl and HOCl are both measured together as “free chlorine”. The equilibrium of hypochlorous acid and hypochlorite is a function of pH . Free chlorine is the most effective form of chlorine for disinfection. The most effective form of free chlorine is hypochlorous acid. One study: These results have been confirmed by several researchers that concluded that HOCl is 70 to 80 times more effective than OCl- for inactivating bacteria. (Culp/Wesner/Culp, 1986). In other words, where it takes 2 minutes to destroy 99% of E. Coli with 0.1 ppm hypochlorous acid, it takes 150 minutes to accomplish the same thing with hypochlorite ion. One system’s chlorine residual of 0.4 ppm is different from another’s in its ability to kill bacteria.
  • Chlorine-based disinfectants are the only disinfectants that provide a residual in the distribution system. This residual is an important part of the multi-barrier approach to preventing waterborne disease. EPA analysis described in GWR: Three factors showing most significant association with no microbial contamination: Operator training Following-up on sanitary survey deficiencies Maintenance of a chlorine residual For smallest systems: Operator training and following up on sanitary survey deficiencies (chlorination is not the silver bullet) Chlorination is not the only measure needed to assure safe drinking water! Coliform bacteria and free chlorine residual testing are two tests used to monitor and assure satisfactory water quality in the distribution system. Daily monitoring and reporting for chlorine residual is required by regulation. Infrequent monitoring and/or inconsistent chlorine residual values increase risk.
  • The addition of hypochlorite compounds increases pH. The addition of chlorine gas decreases pH. Recall previous slide on pH effect on potency. Some facts: Chlorine gas is 100% available chlorine by weight. 1 lbs of chlorine gas = 1 lbs of available chlorine. Gas does not degrade over time. Calcium hypochlorite is available in 65-70% available chlorine by weight. 1.5 lbs of CaOCl = 1 lbs of available chlorine. Degrades very slowly over time – 3% year if kept dry. Sodium hypochlorite is available in 5 – 15% available chlorine by weight. Manufactured by: Cl 2 + 2 NaOH → NaCl + NaClO+ H 2 O It’s heavier than water One gallon of 5.25% household bleach has approximately 0.4 pounds of available chlorine when new. 6% bleach comes in smaller containers, but holds the same weight of available chlorine. Household bleach degrades by 10% in 60 days at 75 F 12.5% bleach degrades by 50% in 60 days at 75% F It decomposes when heated or evaporated to form sodium chlorate and sodium chloride: 3 NaClO → NaClO 3 + 2 NaCl Less common modes of chlorine treatment includes: Chlorine dioxide On-site hypochlorite generation Chloramines are formed when chlorine is introduced in the presence of ammonia or organic nitrogen compounds.
  • Identify components. Ventilation Eye wash Gas alarm Rotometer Eductor Auto-transfer Scale Emergency Planning and Community Right to Know and CERCLA. Threshold = 100 lbs stored. Requirements: Conduct emergency planning. Provide fire service and/or local emergency planning agency with information regarding quantity and location of stored gas. Emergency release notification. Release of more than 10 lbs of gas requires notification of local emergency planning agency, state authorities (DOH), and the National Response Center.   These as well as local and state codes and regulations must be considered during the design and operation of chlorination facilities at a water treatment plant. Chlorine quenching may be necessary (UFC). Spokane (Well Electric) and Wentachee (Rocky Reach Regional Supply) have gone from gas to bulk sodium hypochlorite for safety reasons
  • Describe process
  • What is seen in the picture? Metering pumps Hypochlorite solution tank (recipe based upon changing chlorine strength) Dilution of the NaOCl may produce scaling problems in the pump and/or solution tank (foot valve). Long discharge lines (possible air-binding) Flooded suction
  • NEW SEGMENT – METHODS AND STANDARDS .
  • NEW SEGMENT – METHODS AND STANDARDS .

Chlorination by Muhammad Fahad Ansari 12IEEM14 Chlorination by Muhammad Fahad Ansari 12IEEM14 Presentation Transcript

  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Chlorination Muhammad Fahad Ansari 12IEEM14 Public Health - Always Working for a Safer and Healthier Washington
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Definaton:Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water. SUHAIL RAJPUT 12IEEM27 Public Health - Always Working for a Safer and Healthier Washington
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Our Shared Mission To protect the health of the people by ensuring safe and reliable drinking water. Public Health - Always Working for a Safer and Healthier Washington 3
  • Sources Chlorinated (WA 2008) Sources Chlorinated Sources Sources Not Chlorinated Sources Not Chlorinated Chlorinated 50% 50% 4
  • Group A Residential Population Supplied Chlorinated Water (WA 2008) Supplied Unchlorinated Water 18% Supplied Chlorinated Water Supplied Unchlorinated Water Supplied Chlorinated Water 82% 5
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Chlorination Mechanics How well does chlorine work? Bacteria: Penetrates cell wall and kills the organism Viruses: Relatively effective inactivation Giardia: Relatively ineffective inactivation Public Health - Always Working for a Safer and Healthier Washington 6
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water What Interferes With the Disinfection Process?  High pH  Low water temperature  Turbidity  Insufficient mixing  Presence of chlorine-demanding compounds, such as iron or manganese Public Health - Always Working for a Safer and Healthier Washington 7
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Chlorine treatment standards: “C x T” T = time water is in contact with the chlorine C = concentration of free chlorine (mg/l), measured after “T” Need C x T = 6 for groundwater 0.3 mg/l for 20 min. same as 0.6 mg/l for 10 min. Public Health - Always Working for a Safer and Healthier Washington 8
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Chlorine Chemistry Total = Free chlorine + Combined chlorine Free chlorine: hypochlorous acid + hypochlorite ion Combined chlorine (chloramines): chlorine combined with ammonia or organic nitrogen (causes chlorine taste and odor) Public Health - Always Working for a Safer and Healthier Washington 9
  • Ionization of Chlorine in Water Hypochlorous vs. Hypochlorite 1.2 80% “strong stuff” at a pH of 7.0 1Fraction of Free Chlorine 0.8 HOCl (20oC) “Strong stuff” 0.6 OCl- (20oC) 0.4 20% “strong stuff” at a pH of 8.2 0.2 0 6.0 6.5 7.0 7.5 8.0 8.5 9.0 pH 10
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Chlorine Demand and Chlorine Residual Demand - Inherent properties of the water that consume chlorine Residual - What’s left after the chlorine demand has been satisfied, remaining available to act against microorganisms Public Health - Always Working for a Safer and Healthier Washington 11
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Sources of Chlorine in Drinking Water  Chlorine gas  Calcium hypochlorite (dry)  Sodium hypochlorite (liquid) Public Health - Always Working for a Safer and Healthier Washington 12
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Gas chlorination Public Health - Always Working for a Safer and Healthier Washington 13
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Calcium hypochlorite tablet erosion feed system Public Health - Always Working for a Safer and Healthier Washington 14
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Sodium hypochlorite injection system Solution Tank Injection lines Feed Pumps Public Health - Always Working for a Safer and Healthier Washington 15
  • What Happens to ChlorineAfter it’s Added to Water? HOCl OCl - 16
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water Methods and Standards Industry specifications  American Water Works Association (AWWA)  WA State Department of Transportation Public Health - Always Working for a Safer and Healthier Washington 17
  • Washington State Department of Health Division of Environmental Health Office of Drinking Water THANK YOU Public Health - Always Working for a Safer and Healthier Washington 18