Russell D. Grubbs Water Utilities Manager City of Nacogdoches

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1 Russell D. Grubbs Water Utilities Manager City of Nacogdoches

2 Appreciation of where we are knowing where we have been

3 500 BC, Historical records show that the boiling of water had been recommended even though initially there was no understanding of the principals involved. 1896, Louisville, Kentucky,the first record of chlorine being used directly for water disinfection was on an experimental basis 1897 in England, again on an experimental basis, to sterilize water distribution mains following a typhoid outbreak.

4 1902, Belgium, first continuous use for the dual objective of aiding coagulation and disinfection. 1908, Boonton, New Jersey first permanent continuous use in the United States Contested in court Court found that it represented a publichealth safeguard. This action paved the way for its rapid expansion to other public water supplies in North America.

5 Chloramines Discovered

6 In 1915, the influence of ammonia on the disinfection qualities of chlorine was discovered using aqueous ammonia. This led to prolonging widespread adoption of Chloramine usage, which produced a more stable disinfection residual than chlorine alone chloramines first observed to improve taste and odor problems

7 1926- widespread use of chloramines for taste and odor control 1930 s studies show that taste and odor problems escalate if chloramination not controlled properly In the 1940 s, It was reported that some waters exhibited a break in the chlorine residual curve upon addition of a supplementary amount of chlorine, creating a free chlorine residual.

8 BREAK-POINT CHLORINATION DISCOVERED

9 The most effective chlorine residual is created by break-point chlorination. However, free chlorine may produce undesirable by-products, especially when water that contains organic chemicals is treated Free Chlorine Residual produced by the breakpoint process used to destroy chloramines to rid water of chlorinous taste By WWII, chloramination discontinued due to scarce availability of ammonia

10 Free Chlorine Residual ruled SUPREME in the Water Disinfection Process

11 Free Chlorine Residual ruled SUPREME in the Water Disinfection Process UNTIL..

12 TRIHALOMETHANES DISCOVERED

13 In the 1970 s, researchers in Holland identified a reaction of the free chlorine residual on organic materials. Produced a group of compounds called Trihalomethanes (THMS) Organic material, humic and fulvic acids, origination from decaying vegetative growth THMS were identified as cancer causing agents

14 1986, SDWA amended to add criteria for acceptable levels of THMS EPA encouraged alternative water disinfection methods- reduce THMS 1994 EPA- Disinfectant By-Product Rule stage 1 DBP EPA Disinfectant By-Product Rule stage 2 DBP2 Going back to chloramines in some form or fashion

16 Disinfection - to remove or inactivate pathogenic or disease-causing organisms present in the water. With regard to water treatment, disinfection refers to the destruction or removal of most intestinal or fecal bacteria. Process of disinfection attempts to disrupt the normal life cycle of an organism Penetrating the organisms cell wall disrupts the normal life cycle- either dies or cannot reproduce= bacteriologically safe water

17 Water disinfection does not mean sterilization Most effective form of water disinfection is Boiling, but lacks in practicality Most common form of water disinfection is chlorination

19 Addition of chlorine gas, sodium hypochlorite or calcium hypochlorite to water creates FREE CHLORINE CL 2 + H 2 O- = HOCL + OCL- Hypochlorous Acid= HOCL (dominates at ph <7.5) Hypochlorite = OCL- (dominates at ph >7.5)

20 Hypochlorite ion (OCL-) is negatively charged and meets great resistance while attempting to penetrate the cell wall of an organism Hypochlorous Acid (HOCL) has a neutral charge and readily penetrates the cell wall of an organism and inactivation is achieved rapidly Most effective at a ph of 7.5 or less Very dependent upon concentration and time EPA developed the CT Values for efficient inactivation of Giardia and viruses

21 A variety of reactions take place during chlorination When chlorine is added to any waters containing ammonia (NH 3 ), the ammonia reacts with hypochlorous acid (HOCL) to form monochloramines, dichloramines, and trichloramines. The formation of these chloramines depends on the ph of the water and the initial chlorine-ammonia ratio. Ammonia + Hypochlorous acid = Chloramine + Water

22 Free Chlorine reacts with the fulvic and humic acids that are derived from the decaying vegetation and other organic matter This reaction forms several types of cancercausing agents called Trihalomethanes (THMs) and Haloacetic Acids (HAAS) EPA Mandates Maximum Contaminant Levels of THMs and HAAS

24 Oxidation of all ammonia-nitrogen compounds and all reducing agents Forms Free Chlorine Most effective chlorine based disinfectant Quick kill or inactivation

27 e

30 Addition of ammonia to water creates FREE AMMONIA Ammonium= NH 4 (dominates at ph 9.3) Ammonia = NH 3 (dominates at <ph 9.3) Ammonia + Hypochlorous acid = Chloramine + Water

31 The Full Circle

32 Chloramines do not form THMs or HAAS EPA issued DBP Stage 2 Rule Tighter standards for Trihalomethanes (THM) New Standards for Haloacetic Acids (HAAS) Typically used for maintaining Total Chlorine residual in distribution system(longer lasting) NOT to be used for CT determination

34 Chloramination is the intentional introduction of ammonia into the water treatment process Pre-ammonization- adding ammonia before chlorine ( no CT values) Post-ammonization- adding ammonia after chlorine ( CT can be met before chloramination) Most commonly used method

36 HOCl and NH 3 react to form monochloramines (NH 2 Cl) HOCL + NH 3 --->NH 2 CL + H 2 O (monochloramine) OCl- and NH do not participate in NH 4 2Cl formation Therefore, NH 2 Cl formation is fastest at ph 8.3

37 One Molecule of HOCl reacts with one molecule of NH 3 Chlorine (Cl 2 ) has a molecular weight of 71 lbs Ammonia (NH 3 ) has a molecular weight of 17lbs Nitrogen (N) has an atomic weight of 14 lbs. Therefore,

38 1 mol. Cl 71 lb Cl mol NH 3 Lbs Cl X X = mol Nh 3 1 mol. Cl 2 17 lb NH 3 Lbs NH 3

40 1 mol. Cl 2 71 lb Cl 2 1 mol N Lbs Cl X X = mol N 1 mol. Cl 2 14 lb N Lbs N

42 For our purposes we will look at NH 3 only This is the equivalent to 4.16 mg of free chlorine (as Cl 2 ) per 1.00 mg of free ammonia (as NH 3 ) Roughly a 4.2:1 ratio, has the greatest covalent bond

43 As NH3

44 If free chlorine and free ammonia are added at a ratio that exceeds 4.16 mg free chlorine (Cl 2 ) to 1 mg free ammonia as (NH 3 ), NH 2 Cl reacts with HOCl as follows: HOCl + 2NH 2 Cl N 2 + 3Cl - + 3H + + H 2 O

45 If additional chlorine is added to the ammonia concentration, NH 2 Cl (mono) reacts as follows: NH 2 CL + HOCL---> NHCL 2 + H 2 0 Dichloramine (better disinfectant but, dissipates more rapidly, chlorinous smell) If additional chlorine is added to the ammonia concentration, NHCL 2 (di-) reacts as follows: NHCL 2 + HOCL---> NCL 3 + H 2 0 Trichloramine (taste and odor problems attributed rotten egg smell)

47 Total

51 Relative Relative Concentration Concentration Application ratios used in practice Chlorine Chlorine to to Ammonia Ammonia Application Application Ratio Ratio (mg (mg Cl Cl 2 2 /mg /mg N) N)

Relative Relative Concentration Concentration 1.50 1.50 1.25 1.25 1.00 1.00 0.75 0.75 0.50 0.

25 Ratios encountered when blending chloraminated water with chlorinated water 0.00 0.

52 Relative Relative Concentration Concentration Ratios encountered when blending chloraminated water with chlorinated water Chlorine Chlorine to to Ammonia Ammonia Application Application Ratio Ratio (mg (mg Cl Cl 2 2 /mg /mg N) N)

54 Utilities typically monitor FREE CHLORINE concentration: Sum HOCl + OCl - (HOCL dominates at < ph 7.5) Probably the most practical way to measure chlorine concentrations, but: Poor indicator of disinfection effectiveness, taste & odor issues

55 A combination of testing for Total Chlorine and Free Chlorine can improve the effectiveness of your disinfection Free Chlorine and Free Ammonia cannot coexist to any significant degree Total Chlorine Residual 3.5 mg/l Free Chlorine Residual 3.3 mg/l Free to Total residuals that are equivalent or within 90% is a good indicator of Free Available Chlorine and Break-point has been achieved.

56 DPD Methods for Total Chlorine measures monochloramine, dichloramines, trichloramines, Free Chlorine, and Manganese 3.5 mg/l (T) 3.3 mg/l (FC) 3.5mg/L (T) - Manganese Correction (not required) 3.5mg/L (T) 3.3mg/L (FC) - 0.2mg/L (MC) = 0 mg/l

57 Alternate Scenario- I have a 1.3 mg/l (FC) and I am good to go! Why are customers complaining of taste and odor?

58 Alternate Scenario- I have a 1.3 mg/l (FC) and I am good to go! Why are customers complaining of taste and odor? 3.5 mg/l (T) 0.9mg/L Manganese

59 Alternate Scenario- I have a 1.3 mg/l (FC) and I am good to go! Why are customers complaining of taste and odor? 3.5 mg/l (T) 0.9mg/L Manganese 3.5 mg/l (T) 1.3mg/L (FC) mg/l (MC) = 1.3 mg/l Free Residual looks good, but results in dichloramine or trichloramine formation

61 Utilities typically monitor TOTAL CHLORINE concentration: Sum of NH 2 Cl, NHCl 2, NCl 3, organochloramines, HOCl, OCl - Probably the most practical way to measure chloramine concentrations, but: Poor indicator of disinfection effectiveness, taste & odor issues

62 A combination of testing for Total Chlorine, Free Chlorine, and Free Ammonia can improve the effectiveness of your disinfection Free Chlorine and Free Ammonia cannot coexist to any significant degree Total Chlorine Residual 3.5 mg/l Free Chlorine Residual 0.35 mg/l (goal is ZERO) Free Ammonia goal is ZERO Free to Total residuals that are 10% or less is a good indicator of monochloramine formation.

63 DPD Methods for Total Chlorine measures monochloramine, dichloramines, trichloramines, Free Chlorine, and Manganese 3.5 mg/l (T) 0.3mg/L (FC) 0 (FA) 3.5mg/L (T) - Manganese Correction (not required) 3.5mg/L (T) - FC - 0.3mg/L (MC) = 3.2 mg/l Monochloramine Formation Achieved

64 Alternate Scenario I have 3.5 mg/l (T) and I am good to go!

65 Alternate Scenario I have 3.5 mg/l (T) and I am good to go! Why are customers complaining of taste and odor?

66 Alternate Scenario I have 3.5 mg/l (T) and I am good to go! Why are customers complaining of taste and odor? 1.3 mg/l (FC) 0.9mg/L Manganese

67 Alternate Scenario I have 3.5 mg/l (T) and I am good to go! Why are customers complaining of taste and odor? 1.3 mg/l (FC) 0.9mg/L Manganese 3.5 mg/l (T) 1.3mg/L (FC) mg/l (MC) = 1.3 mg/l Total residual looks good, but results in dichloramine or trichloramine formation

68 25 ml sample water Potassium Iodide Solution add 3 droplets, stir Sodium Arsonite Solution add 3 droplets, stir Add 25 ml Total DPD powder, stir Wait 3 minutes Test for Total Residual

69 Monochloramine Testing (MonoChlor) Tests for Monochloramines only Make sure you are testing for Free Chlorine as well as Free Ammonia

71 Anhydrous Ammonia (NH 3 ) 4.16 to 1 ratio---> 4.16 lbs chlorine, 1 lb anhydrous ammonia Based upon chlorine residual, not demand 50 lbs/day Cl 2 divided by 4.16 = 12.0 lbs/day AA All waters are different, adjust chlorine down or adjust ammonia up to achieve YOUR optimal dosage Small incremental adjustments ONLY

72 Liquid Ammonium Sulfate (LAS) (NH 3 ) Free Cl 2 Res. (mg/l) X Flow Rate (gpm) X 0.35 = LAS (mls/min.) LAS Concentration (% ) X Sp. Gv. 3.5 mg/l X 650 gpm X 0.35 = mls/min 38(%) X 1.2 (sp. gv.) 17.5 mls/min X 1440 min/day = mls/day /3785ml/gal = or 6.7 gal/day Set liquid chemical feeder to 6.7 gal/day

73 Checking Your Cl 2 to NH 3 Ratio using Liquid Ammonium Sulfate (LAS) Typically 38-40% ammonium sulfate (NH 4 ) 2 SO 4 content Typically ammonia (NH 3 ) is 25.8% of the ammonium sulfate content See Material Safety Data Sheet (MSDS)

74 Checking Your Cl 2 to NH 3 Ratio using Liquid Ammonium Sulfate (LAS) Our LAS contains 38% ammonium sulfate Our LAS has a specific gravity of 1.22 Each gallon of water weighs 8.34 lbs 1 lb LAS X 38% ammonium sulfate = 0.38 lbs of ammonium sulfate per lb of LAS

75 Checking Your Cl 2 to NH 3 Ratio using Liquid Ammonium Sulfate (LAS) gpd LAS x 8.34 x SP.Gv. = lbs of LAS/day 6.7 gpd LAS x 8.34 x 1.22 = lbs LAS lbs LAS x 38% AS = 25.9 lbs of AS 25.9 lbs of AS x 25.8% NH 3 = 6.68 lbs NH 3 /day

76 Checking Your Cl 2 :NH 3 Ratio 650gpm X 1440 minutes/day = 936,000 gpd water.936 MGD x 8.34 X 3.5 Cl 2 residual =27.3 lbs Cl 2 /day 27.3 lbs Cl2/day 6.68 lbs NH3/day = 4.08 = 4.08: 1 ratio

77 Remember Chlorine Dosage = Demand +Residual MGD X 8.34 X mg/l = pounds per day Our sodium hypochlorite bleach is 12.5% available chlorine Has a specific gravity of 1.28 Gallon of water weights 8.34 lbs

78 8.34 X 1.28 Sp. Gv. of bleach = lbs/ gallon of bleach 1 lb bleach x 12.5 % available chlorine =.125 lbs available chlorine Gallon of bleach weights10.68 lbs and has 1.25 pounds of Free Available Chlorine 1MGD x 8.34 X 5mg/L = 41.7 lbs per day of 100% Cl2

79 Lbs of Cl2 lbs of Bleach Day X Lbs of Cl2 = lbs of bleach / day 41.7 lbs of Cl2 lbs of Bleach Day X lbs of Cl2 = lbs Bleach / day

80 Lbs of Cl2 lbs of Bleach Day X Lbs of Cl2 = lbs of bleach / day 41.7 lbs of Cl2 lbs of Bleach Day X lbs of Cl2 = lbs Bleach / day

81 Lbs of Cl2 lbs of Bleach Day X Lbs of Cl2 = lbs of bleach / day 41.7 lbs of Cl2 lbs of Bleach Day X lbs of Cl2 = lbs Bleach / day lbs bleach 1 gal of bleach Day X lbs = gallons of bleach / day

82 Lbs of Cl2 lbs of Bleach Day X Lbs of Cl2 = lbs of bleach / day 41.7 lbs of Cl2 lbs of Bleach Day X lbs of Cl2 = lbs Bleach / day lbs bleach 1 gal of bleach Day X lbs =31.2 gals bleach / day 31.2 gallons of 12.5% Bleach = 41.7 lbs of 100% chlorine gas

83 Diaphragm Pump

84 Max GPD X Speed (%) X Stroke (%) = Feed Rate 25 Maxgpd X 0.50 X 0.50 = 6.25 GPD Feed Rate

85 Max GPD X Speed (%) X Stroke (%) = Feed Rate 25 Maxgpd X 0.50 X 0.50 = 6.25 GPD Feed Rate Feed Rate = Stroke (%) Maxgpd X Speed (%)

86 Max GPD X Speed (%) X Stroke (%) = Feed Rate 25 Maxgpd X 0.50 X 0.50 = 6.25 GPD Feed Rate Feed Rate = Stroke (%) Maxgpd X Speed (%) 6.25 gpd = 50 % Stroke 25Maxgpd X 0.50 Speed

88 Nitrifying bacteria convert free ammonia to nitrite Complete nitrification when nitrifying bacteria converts nitrites to nitrates Free Ammonia in the distribution system can cause nitrifying bacteria to grow into colonies called Biofilm Excessive Free Ammonia from chloramination Excessive Free Ammonia from Chloramine decay

89 Causes Excessive Free Ammonia Long Detention times (water age) Warm Waters Lower Chloramine residuals which may result in violating TCEQ regulations, <0.5 Total chlorine residual and, Elevated levels nitrites and nitrates

90 What the heck is that?

91 Biofilm is nitrifying organisms such as nitrobacters and nitrosomas that feed off excessive free ammonia in the distribution system Sediments in the pipeline allow them to hid from chloramination process at lower residuals, typically lower than 2.0T These organisms convert free ammonia to nitrates and nitrites, which consume chloramine residuals

92 What Can I Do?

93 Monitor and control free ammonia Higher Chloramine Residuals >2.0mg/L in the far reaches of distribution system Higher Chloramine Residual greater than 2.0 mg/l has been shown to reduce Heterotrophic Bacteria (biofilm) than Free Chlorine

94 Optimal Chlorine to Ammonia Ratio Increasing drawdown and/or mixing in storage tanks (reducing water age) Looped system, eliminating dead-ended mains Adequate flushing program

95 Detection of early signs of nitrification Typical drop in Total Chlorine residual in distribution system between mg/l Higher drop may signal nitrification High nitrate or nitrites- know your baseline Loss of chlorine residual, no apparent reason

96 Best cure is prevention Nitrification- once you got it, hard to control Switching to Free Chlorine (burn-out) of the nitrification may be only choice if nitrification is significant and violations imminent Time consuming Elevated THMS Taste and odor problems Customer complaints Waste of funds

97 Must have TCEQ written approval Notify sensitive consumers (i.e., dialysis clinics, aquarium owners) Have a Plan

98 See EPA s DAM5 for more detailed info it s free! Any Questions?

99 Lee Odell, Controlling Nitrification in Chlorimanated Systems, AWWA, Journal, 1996 Y. Koby Kohen et al, Nitrification: Causes, Prevention, and Control, AWWA Journal, 2001 Gregory J. Kirmeyer, Glenn W. Foust, Gregory l. Pierson, Joseph J. Simmler, Optimizing Chloramine Treatment, AWWA Research Foundation, 1993 Walter O. Brien, Disinfection of Water TWUA manual of Water Utility Operations, 8 th,1988 Connell, Gerald F., The Chlorination/Chloramination Handbook, 1996 AWWA EPA s Directed Assistance Module (DAM5)

Science of Chloramination. Maine Water Utilities Association June 8, 2010

Science of Chloramination. Maine Water Utilities Association June 8, 2010 Science of Chloramination June 8, 2010 What is chloramination? Chloramination is the process of disinfecting water using chloramines, compounds of chlorine and ammonia. The use of chloramines in the United