Chlorination / DeChlorination Procedures

Transcription

1 Chlorination / DeChlorination Procedures -A New Twist to an Old Technology- Robert Gordhamer Measurement Technologies, Inc. Redmond, Washington

2 Chlorination / Dechlorination Field Chlorination Forms of chlorine Reducing the amount of chlorine Methods of chlorination Field Dechlorination Discharge requirements Dechlorination chemicals Methods of dechlorination

3 FIELD CHLORINATION AWWA/ANSI C Disinfecting Water Mains First standard approved Sept. 30, 1947 Latest revision June 1, 2005 Standards are reviewed every five years. AWWA standards describe minimum requirements AND is not a SPECIFICATION.

4 Forms of Chlorine Liquid chlorine (Cl 2 )... Calcium hypochlorite (Ca(OCl) 2 ) granules or tablets... Sodium hypochlorite (NaOCl) solution... *It is recommended that you follow the current AWWA C651 specification with the following modifications.

5 FIELD CHLORINATION Liquid Chlorine Least expensive with the highest danger. Requires specially trained treatment crews. Requires safety equipment for the operator and all other personnel at the site. Requires containment container for cylinder.

6 FIELD CHLORINATION Calcium Hypochlorite (HTH) Available in two forms Tablets Granular Contains approximately 65% available chlorine. Placed in pipeline during construction. Recommended to be used in pipe sizes to 24 diameter.

7 FIELD CHLORINATION Sodium Hypochlorite Contains between 5% to 15% available chlorine. (12.5% typical) Available in 1 qt. to 55 gallon containers. Must be stored properly to prevent deterioration. Must be NSF 60, household bleach is not an acceptable chlorine.

8 What determines how hot you cook the line Chlorine Residual Level The specifier determines the chlorine residual level the line should be targeted for? Did your crews let dirt get into the pipeline during the installation? Did you not seal the pipeline at night? Could there be animals inside the line?

9 How can I use less Chlorine

10 Alternate Procedures

11 Alternate Procedures

12 Disinfecting Water Mains Basic Disinfection Procedure 1. Inspect materials to insure their integrity. 2. Preventing contaminating materials from entering the watermain. 3. Remove, by flushing those materials that may have entered the line. 4. Pressure test new installation. 5. Chlorinating the new installation cont.

13 Disinfecting Water Mains Basic Disinfection Procedure 6. Document that an adequate level of chlorine contacted each pipe. 7. Flushing the highly chlorinated water from the main. 8. Determining the bacteriological quality by laboratory test after disinfection. 9. Final connection of the approved new water main to the active distribution system.

14 How do you COOK a line? Tablet or Granular Continuous-feed method Slug method NOW...

15 By using a Modified Continuous-Feed method. Mixes the chlorine solution with every gallon of water that is filling your new system. This will insure total contact at the desired chlorine residual level.

16 Why use a combination Venturi / Orifice Design? Reliability

17 How does an Orifice design work?

18 The size of the orifice determines performance.

19 How does a venturi design work?

20

21 The lateral by-pass venturi works by combining two principles together 2 Mainline orifice. Plus three additional orifice insert And,

22 And the lateral by-pass venturi

23 Side view - Showing the mainline orifice ring. Flow direction This orifice directs part of the water flow into the lateral bypass venturi. By inserting the smaller orifices you can control your discharge rate OR increase bypass pressure to insure a full vacuum is achieved.

24 Incoming water flow Pressurizes the lateral by-pass to start the vacuum.

25 When the by-pass water re-enters the main flow, it will enter at the higher incoming pressure.

26 The Pros & Cons of Venturi / Orifice designs The smaller the opening, the quicker you get a vacuum, HOWEVER, you take away high flow performance. The larger the opening, the higher the flow must be before a vacuum is achieved. This takes away low end performance.

27 Lateral By-Pass Venturi Design with Mainline Orifice FEATURES: Full vacuum throughout entire flow range. Wide range of FLOW. Controllability of feed solution.

28 Lateral By-Pass Venturi Design with Mainline Orifice CONSISTENT FEED RATE: ONE GALLON per minute, FROM START TO FINISH. Feed control valve allows for proper balancing of feed solution. Gives operator the ability to make feed solution strength based on flow.

29 Chlorinating Set-Up

30 Source Hydrant Any length of hose can be attached in front of the venturi device...

31 Chlorinating Set-Up Source Hydrant No outside power required when you use a venturi style device. Enter point

32 Chlorinating Set-Up

33 Testing for CRL Locate sampling points, having the first point within ten feet of the entry point. Number of sampling points to be determined by the size of the project.

34 Set-up Discharge area You will need to discharge water from the system during the chlorinating operation. Some of this water will have a chlorine residual level that needs to be neutralized.

35 Entry Point

36 Device with Test Port

37 Taking a test sample

38 Procedure for chlorinating the system Adjust feed control valve to full open position. Turn on the water supply to start filling. Test chlorine residual level at a sample point within ten feet of the entry point. Follow Engineer s specifications on the chlorine residual level. Take test samples at selected sites throughout the project. Adjust the control valve to increase or decrease the amount of chlorine entering the system.

39 COOK

40 Dechlorinate

41 Liability If you allow chlorinated water to be discharge into the environment and you have not enforced your state regulations, YOU will share in the responsibility. OR, in other words the fine. This will be true for the consulting engineer, the owner and the person or company that discharges the chlorinated water.

42 EPA has set guidelines The US-EPA has a recommended set of guidelines. Each state has adapted there own standards. Some states, have even broken it down into regions. However, all states have discharge limits on chlorine or chloraminated water. AWWA is developing a new dechlorination standard.

43 And, it s good for the Environment Even a trace of chlorine will kill fish. Your discharge water effects the beginning of the food chain.

44 Washington, Oregon and Idaho s Requirements Regulation Standard: State Controlled DISCHARGE LIMITS: Fresh Water CMC (Acute) 19 ug/l Fresh Water CCC (Chronic) 11 ug/l

45 mg/l vs. ug/l mg/l means milligrams per liter or parts per million (PPM). 1 mg/l = 1 PPM ug/l means micrograms per liter or parts per billion (PPB). 1 ug/l = 1 PPB

46 Convert ug/l (PPB) to mg/l (PPM) To convert micrograms per liter to milligrams per liter, divide by ug/l divided by 1000 = mg/l 19 ug/l divided by 1000 = mg/l.8 mg/l multiplied by 1000 = 800 ug/l PPB

47 What you should know So, you are going to specify DECHLORINATION. There are many different styles of dechlorination devices, so be sure, that if you specify a device that it works at the chlorine residual levels that will be encountered.

48 Liability Consideration should be given to specifying only the performance that is needed and let the contractor determine what equipment to use to achieve the chlorine residual level specified for the discharge. This way you do not assume liability on what equipment was used.

49

50 Dechlorination Two major methods of Dechlorination Non-Chemical Dechlorination Only to be used for low chlorinated water. Chloraminated water can take 3 4 times longer to decay the chlorine residual. Chemical Dechlorination Faster and more predictable method. Available in solid, liquid and gaseous forms. Works well with chloraminated water.

51 Non-Chemical Methods for Dechlorination Holding Tanks or Ponds Land Applications Groundwater recharge Releases though hay bales Discharge into Strom Sewers Discharges into Sanitary Sewers

52 Chemical methods for Dechlorination Types of Chemical Dechlorination Drip style devices Injection Pumps Passive device Vacuum - Induced

53 Forms of Dechlorination Equipment Passive A device which requires that the water discharge to make contact with the dechlorination chemical. Vacuum-induced Any device that produces a vacuum and provides a means of controlling the flow of dechlorination chemical.

54 Tablet style devices

55 Liquid Feed style devices

56

57 Dechlorination Chemicals Common chemicals used in field dechlorination Sodium Sulfite Sodium Thiosulfate Sodium Bisulfite Ascorbic acid Sodium Ascorbate Calcium Thiosulfate

58 Why should you use only environmentally safe chemicals We are neutralizing the chlorine to protect aquatic life. We have to be aware of ph. NO effect dissolved oxygen in the water. Safe for humans to handle. Easier shipping and handling of freight.

59 What chemicals are safe for aquatic life? Calcium Thiosulfate (Domestic) Liquid solution Ascorbic acid (Imported) Granular or tablet form Sodium Ascorbate (Imported) Granular form only

60 Cost comparison of chemicals that are safe for aquatic life? Calcium Thiosulfate (Domestic) Low cost Ascorbic acid (Imported) Granular three times the cost Tablet five times the cost Sodium Ascorbate (Imported) Granular over 6 times the cost

61 Basic Dechlorination Procedure The selected dechlorination process must be able to neutralize the chlorine to levels below 0.01 mg/l. Testing needs to be done at the point of discharge, the point you lose control of the water flow. Spread dechlorination chemical in the path of the discharge water to insure that the initial water will make contact with the chemical.

62 Basic Dechlorination Procedure Make sure that either your feed solution or your tablet chamber has the proper amount of chemical to handle the chlorine residual to be neutralized. Start your discharge and check your chlorine residual at the discharge point. Make any adjustments that may require proper neutralization of chlorine.

63 Basic Dechlorination Procedure If using a manufactured device follow the manufacturers directions. Monitor chlorine residual at per determine times during the discharge and record in log book. When you achieve the desired chlorine residual level in your discharge water, stop flushing.

64 Required Equipment Proper dechlorination device that will neutralize the chlorine residual. The proper amount of dechlorination chemical. Proper chlorine test equipment that will measure to 0.01 mg/l this means TEN PARTS PER BILLION.

65 Set-up Discharge area You will need to discharge water from the system during the flushing operation. Make sure that the area will handle the amount of the discharge. Store chemicals properly. Set-up additional monitoring equipment.

66 Set-up Determine where the device will be located in relationship to the discharge point from the outlet of the system. It is preferred to have the discharge point away from the device.

67 Testing for chlorine Set-up

68 Testing your discharge If your test shows no chlorine, turn feed solution control valve down until you show a sign of chlorine in your discharge. Then open feed solution control valve a slight amount to balance feed solution strength to chlorine residual discharge. As you are flushing you may test your incoming residual level of chlorine by drawing a sample from the make-up water valve.

69 Always Dechlorinate when discharging chlorinated water

70 For more information: Measurement Technologies, Inc. P.O. Box 2195 Redmond, WA VITC (8482) E-Fax: www. H2ONeutralizer.com 2009