CEE 597B DBPs CEE/EHS 597B Class #15: Special Treatment Issues: DBPs Dave Reckhow 2 1
CEE 597B DBPs 2007 John #1: Dr. John Snow 1813-1858 Cholera First emerged in early 1800s 1852-1860: The third cholera pandemic Snow showed the role of water in disease transmission London’s Broad Street pump (Broadwick St) Miasma theory was discredited, but it took decades to fully put it to rest 3 Soho, Westminster 4 Picadilly Circus 2
CEE 597B DBPs Photo courtesy of the Leal family and Mike McGuire John #2: Dr. John L. Leal Jersey City’s Boonton Reservoir Leal experimented with chlorine, its effectiveness and production 1858-1914 George Johnson & George Fuller worked with Leal and designed the system (1908) “Full-scale and continuous implementation of disinfection for the first time in Jersey City, NJ ignited a disinfection revolution in the United States that reverberated around the world” M.J. McGuire, JAWWA 98(3)123 5 Chlorination 1-2 punch of filtration & chlorination Greenberg, 1980, Water Chlorination, Env. Impact & Health Eff., Vol 3, pg.3, Ann Arbor Sci. US Death Rates for Typhoid Fever 6 Melosi, 2000, The Sanitary City, John Hopkins Press 3
CEE 597B DBPs Conventional Treatment: 1910-present Coagulation & solids separation rapid mix, flocculation, settling, filtration Disinfection including clearwell for contact time Most common for surface water Corrosion Control Fluoride Coagulant Chlorine Dist. Sys. Clear well raw water rapid flocculation Settling Filtration 7 mix John #3: Johannes J. Rook Short Biography Education PhD in Biochemistry: 1949 Work experience Technological Univ., Delft (~‘49-’54) 1921-2010 Laboratory for Microbiology Early Research Lundbeck Pharmaceuticals in Copenhagen, (~’55-?) 1955, Microbiological Deterioration of Noury Citric acid Factory (in Holland) Vulcanized Rubber Amstel Brewery Applied Micro. Rotterdam Water Works by 1963, chief chemist 1964, secured funds for a GC at (1964-1984). Rotterdam 1984-1986; Visiting Researcher at Lyonnaise des Carlo Erba with gas sample loop Eaux, Le Pecq. 8 4
CEE 597B DBPs John Rook & DBPs Major Contributions Brought headspace analysis from the beer industry to drinking water T&O problems Found trihalomethanes (THMs) in finished water Carcinogens !?! Published in Dutch journal H2O, Aug 19, 1972 issue Deduced that they were formed as byproducts of chlorination Proposed chemical pathways 9 Rook, 1974, Water Treat. & Exam., 23:234 DBP Epidemiology Bladder Cancer Basis for current DBPs linked to 9,300 US cases every year EPA regulation Other Cancers 80 µg/L THMs 60 µg/L HAAs Rectal, colon Reproductive & developmental effects Miscarriages & Low birth weight 20 µg/L THMs - high risk Birth Defects Hwang et al., 2008 e.g., Cleft palate, neural tube defects Other Kidney & spleen disorders Immune system problems, neurotoxic effects 5
CEE 597B DBPs 11 Reactants Products Reduced Oxidized Inorganics Inorganics & inorganic Cl - HOCl DBPs OH - O 3 NH 4 + NH 2 Cl ClO 2 - ClO 2 & Organic DBPs Oxidized NOM NOM 6
CEE 597B DBPs Formation of Cl 2 -driven DBPs Cl 2 The Halogenated DBPs NaOCl • THMs • HAAs and other haloacids Br-, I- • Haloaromatics • N-halo compounds • Halo-nitriles, aldehydes, nitros, etc OBr-, I 3 - NH 3 ~10% The non- NH 2 Cl halogenated DBPs CO 2 + Oxidized Natural Organic Organic ~90% Mater Compounds • Acids Anthropogenic • Aldehydes Chemicals • Ketones (PPCPs, Ag & 13 • Nitrosamines industrial products) Reactions with Disinfectants: Chlorine Oxidized NOM The Precursors! and inorganic chloride HOCl •Aldehydes + natural organics Chlorinated Organics (NOM) •TOX •THMs •HAAs The THMs Br Br Br Cl C H Cl H Br C H C H Br C Cl Cl Br Cl Cl Chloroform Bromodichloromethane Chlorodibromomethane Bromoform 14 7
CEE 597B DBPs The Haloacetic Acids HAA5 & HAA6 include the two monohaloacetic acids (MCAA & MBAA) plus One of the trihaloacetic acids: Br Br Cl Br COOH Cl C C COOH COOH C COOH Br Cl C Br Cl Cl Br Cl Trichloroacetic Bromodichloroacetic Chlorodibromoacetic Tribromoacetic Acid Acid Acid Acid (TCAA) HAA6 only Br Cl Br And 2 or 3 of the COOH H C H C COOH H C COOH dihaloacetic acids Cl Br Cl Dichloroacetic Bromochloroacetic Dibromoacetic Acid Acid Acid 15 15 (DCAA) Haloacetonitriles Others that are commonly measured, but not regulated include the: Br Br Cl Dihalo- H C C N H C C N H C C N acetonitriles Cl Br Cl Dichloroacetonitrile Bromochloroacetonitrile Dibromoacetonitrile (DCAN) (BCAN) (DBAN) Cl Trihaloacetonitriles N Cl C C Cl Trichloroacetonitrile 16 16 (TCAN) 8
CEE 597B DBPs Halopropanones As well as the: O H Cl etc dihalopropanones C C C H H H Cl 1,1-Dichloropropanone (DCP) trihalopropanones O O Br H Cl H etc. C C H Cl C C C H Cl C Cl H Cl H 1,1,1-Trichloropropanone 1,1,1-Bromodichloropropanone (TCP) 17 17 Factors Affecting DBP Formation Time pH Dose Temperature Bromide/Ammonia Pretreatment Reactions with pipe walls & attached materials “I think you should be more explicit here 18 in step two” 9
CEE 597B DBPs 1300 600 20 mg/L chlorine dose pH 7.0 1200 Time 20 o C 1100 500 TOX 1000 Major 900 THM, HAA Concentration ( g/L) Byproducts 400 TOX Concentration ( g/L) 800 700 300 600 TCAA 500 TTHM 200 400 300 Aquatic 100 200 DCAA NOM 100 0 0 0 20 40 60 80 100 120 140 160 300 350 19 (after Reckhow & Singer, 1984) Time (hrs) 1400 1200 pH Effects 1000 TOX Concentration ( g/L) 800 600 400 TCAA + DCAA TTHM 200 0 0 2 4 6 8 10 12 20 pH 10
CEE 597B DBPs Significance of Bromide Present in surface and groundwaters Concentrations are highly variable Not removed by most treatment processes Readily oxidized by chlorine k HOCl Br HOBr Cl 2 1 1 4 7 10 . [exp( )] 754 9 . k x M s T 3 1 1 37 10 . @ 25 x M s C Therefore, bromide has a 13 second half life at pH 7, and 1 mg/L residual chlorine 21 Impact of Bromide on THM Formation 100 Data from: Minear & Bird, 1980 96 hours, pH 7.0 5 mg/L Chlorine Dose 80 CHCl 3 1 mg/L Humic Acid Percent of TTHM CHBr 3 60 CHBr 2 Cl 40 CHBrCl 2 20 0 0.0 0.4 0.8 1.2 1.6 2.0 22 Bromide Concentration (mg/L) 11
CEE 597B DBPs Bromide: THAA Formation Note that TCAA is the only regulated THAA 330 pH 7, 25 o C, 7 days 300 CCl 3 COOH 25 mg/L chlorine dose 270 2.9 mg/L TOC Concentration ( g/L as Cl - ) 240 CClBr 2 COOH 210 180 CCl 2 BrCOOH CBr 3 COOH 150 120 90 60 30 0 0 1 2 3 4 5 Bromide Concentration (mg/L) From Pourmoghaddas, 1990 23 Case Study: Impact of time & chlorine dose 6 Cl 2 Demand 5 Chlorine Demand (mg/L) 4 3 2 Chlorine Dose 1 2.5 mg/L Loss of Residual 5 mg/L 10 mg/L 0 0 20 40 60 80 100 120 24 Time (hrs) 12
CEE 597B DBPs Case Study: Impact of time & chlorine dose 220 200 THM 180 Total Trihalomethanes ( g/L) 160 140 120 100 80 60 Chlorine Dose 40 2.5 mg/L Loss of Residual 20 5 mg/L 10 mg/L 0 0 20 40 60 80 100 120 25 Time (hrs) THMs from Chlorination Chlorine Residual @ 48 hrs std = 0.8 mg/L 60 55 opt = 0.2 mg/L 50 Temp 45 THM Formation ( g/L) Low = 13 C 40 High = 23 C 35 30 25 20 1-Chlorine: std dose: low temp 15 2-Chlorine: std dose: high temp 3-Chlorine: opt dose: low temp 10 4-Chlorine: opt dose: high temp 5 0 26 0 20 40 60 80 100 Reaction Time (hours) 13
CEE 597B DBPs THMs from Chloramination Addition of ammonia after 5 hrs free contact time 45 End of Initial Free Chlorine Contact Period 40 35 THM Formation ( g/L) 30 25 20 5-Chloramine: mid dose: 4.0 Cl 2 /N: low temp 15 6-Chloramine: mid dose: 4.9 Cl 2 /N: low temp 7-Chloramine: mid dose: 6.0 Cl 2 /N: low temp 10 8-Chloramine; low dose: 4.9 Cl 2 /N: low temp 9-Chloramine: high dose: 4.9 Cl 2 /N: low temp 5 10-Chloramine: mid dose: 4.9 Cl 2 /N: high temp 0 0 20 40 60 80 100 27 Reaction Time (hours) DBP Modeling Power function models (Empirical) simple to use greater experience Chemical kinetic models (Semi-mechanistic) depends on time-varying concentrations of the precursors (reactants) better adapted for use with a more integrated framework combine with degradation terms combine with hydraulic/reactor models Chlorine boosting 28 14
Recommend
More recommend
