Print version CEE 697z Organic Compounds in Water and Wastewater NOM and DBPs Special Lecturer: Rassil El Sayess Lecture #9 http://www.ecs.umass.edu/eve/research/nyc_chloramines/literature.html Dave Reckhow - Organics In W & WW
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 Mater ~90% Compounds Acids • Anthropogenic Aldehydes • Chemicals Ketones • (PPCPs, Ag & 2 Nitrosamines • industrial products)
Other Compounds THMs, THAAs The DBP Iceberg DHAAs ICR Compounds Stuart Krasner AWWA 50 MWDSC DBPs ~700 Known DBPs Susan Richardson USEPA Non-halogenated Halogenated Compounds Compounds
The Trihalomethanes (THMs) Br Br Br Cl H C Cl C H H Br C C H Br Cl Cl Br Cl Cl Chloroform Bromodichloromethane Chlorodibromomethane Bromoform Published in Dutch journal H2O, Aug • 19, 1972 issue Deduced that they were formed as • byproducts of chlorination Proposed chemical pathways • Rook, 1974, Water Treat. & Exam., 23:234 4 1921-2010
Treated Waters: TTHMs from US Surveys Occurrence Assessment for the Final Stage 2 DBPR, 12/05, USEPA 5 5
The Haloacetic Acids (HAAs) HAA5 include the two monohaloacetic acids (MCAA & MBAA) plus One of the trihaloacetic acids: Br Br Br Cl C COOH Cl COOH C C COOH Br COOH Br C Cl Cl Br Cl Cl Trichloroacetic Bromodichloroacetic Chlorodibromoacetic Tribromoacetic Acid Acid Acid Acid (TCAA) And 2 of the Br Br Cl dihaloacetic acids H C COOH COOH C H C COOH H Cl Br Cl Dichloroacetic Bromochloroacetic Dibromoacetic Acid Acid Acid 6 6 (DCAA) (DBAA)
Regulated Compounds THMs HAA5 Bromate Chlorite The regulated compounds are Common “end products” produced by almost all precursors Chemically very stable This is not typical of other DBPs
DBP Precursor Materials General Groups Specific Structures Bulk NOM Lignin Hydrophobic NOM Carbohydrates Acids (Fulvics & Humics) Proteins & Amino Acids Neutrals Terpenoids Bases Hydrophilic NOM Fatty Acids Acids, Bases, Neutrals Tannins Mesophilic NOM Anthropogenics Acids, Bases, Neutrals Ranitidine Soluble Metabolics
DBP Data - Availability Based on precursors Bulk NOM: most data, from raw & treated waters NOM Fractions: some data Specific Structures: far less data Based on type of DBP Regulated compounds (THMs & HAAs) Extensive Data, especially for bulk NOM Common unregulated compounds Moderate level, especially from ICR and selected “studies” Emerging unregulated compounds Very little data
1300 600 20 mg/L chlorine dose pH 7.0 1200 Fulvic Acid 20 o C 1100 500 TOX 1000 900 THM, HAA Concentration ( µ g/L) 400 TOX Concentration ( µ g/L) 800 700 300 600 TCAA 500 TTHM 200 400 300 100 200 DCAA 100 0 0 0 20 40 60 80 100 120 140 160 300 350 10 (from: Reckhow & Singer, 1984) Time (hrs)
Some Common Unregulated DBPs 10 Many decrease with Chlorinated Raw Drinking Water time from New Jersey (MacNeill's UMass thesis, 1994) Degradation DCAN 8 Chemical Concentration ( µ g/L) 6 Biological 1,1,1-TCP Not shown 4 Chloropicrin 2 1,1-DCP 0 0 20 40 60 80 100 120 140 160 11 Time (hrs)
Model Compound Studies Model compounds Synthetically prepared in the lab: water that has been spiked with certain compounds Most have been used to assess formation of regulated DBPs (THMs & HAAs) Some have been conducted to find new DBPs and especially intermediates formed along the way to the final byproducts
Lignin: Halobenzoquinones (HBQs) H H O O Cl Cl 4 HOCl Lignin? Many pathways Cl Cl O O H H Plants to HQs H H O O O Cl Cl Cl Cl Cl Cl OH Cl Cl Cl Cl Cl Toxicity Cl Cl HCl Cl O O O 5 H HQs are known to be reactive and damaging to DNA Postulated to be bladder carcinogen of high potency Bull et al., 2006 13
Halobenzoquinones (cont.) Identified following QSAR deductive reasoning SPE - LC/MS/MS method: Zhao et al., 2010 Little occurrence data: U Alberta: 7 samples in 2 publications Dichloro (DCBQ): 14 ng/L median (165 ng/L max) Others much lower UMass: several dozen samples - unpublished Dichloro: 306 ng/L high value 14
Formation Potential Experiments designed to maximize exposure of water to chlorine (in this case) under optimal conditions and measure the concentration of DBP for a specified duration Disinfection by-product formation potential (DBP-FM): 72 hr, 20 mg/L Cl2 dose, pH 7, 20C Simulated distribution system (SDS) test: 24 hr, 4 mg/L Cl2 dose, 20C and pH 7 Dave Reckhow - Organics In W & WW
THM-FP From: Reckhow et al., 2007 WRF Report #91186 From: Reckhow et al., 2006 Formation Potential conditions: 60 120 Surface Waters 72 hrs, 20 mg/L Cl 2 , pH 7, 20C AWWARF report (in press) Groundwaters Specific THM-SDS ( µ g/mg-C) 50 Specific THMFP ( µ g/mg-C) 100 40 80 30 60 45 µg-THM/mg-C 20 40 Median 10 20 Value 0 0 0.0 0.2 0.4 0.6 0.8 1.0 16 16 Cumulative Frequency
FP and SDS for NOM Fractions Cumulative Frequency Plot for THM Precursor Content in Major RW Fractions 0.6 Untreated Waters Only 60 120 Philic 0.5 Specific THM-SDS ( µ g/mg-C) Phobic 50 Specific THMFP ( µ g/mg-C) 100 Pre-exponential Term (a) Trans 0.4 40 80 0.3 30 60 0.2 20 40 0.1 10 20 0 0 0.0 0.0 0.2 0.4 0.6 0.8 1.0 Cumulative Frequency 17
Formation Potentials of NOM Fractions 70 60 TTHMFP (µg/mg-C) 50 40 30 20 10 0 Weak Acids Fulvic Acid Humic Acid Neutrals Neutrals Bases Bases Acids 18 18 Hydrophilic Hydrophobic
TOX Formation NOM Cl-DBPs Br NOM TOX HOBr Br-DBPs HOCl HOI NOM I I-DBPs TOX=TOCl + TOBr + TOI Other disinfectants: NH 2 Cl, O 3 , ClO 2 From: Guanghui Hua; 2004 WQTC David Reckhow
What do we know so far? Approximately 50% of the TOX formed by drinking water chlorination is not accounted for concern about the identity and concentrations of DBPs Not feasible to account for each and every compound that might be formed in disinfected water TOX: A surrogate measure for organically-bound halogenated DBPs in a disinfected water sample. Comparing the TOX vales with the halides attributed to the identified DBPs: allow for the estimation of the unidentified TOX TOX analyzers: used to quantify amounts of organically-bound chlorine, bromine and iodine in raw and disinfected water samples
TOX: Known & Unknown Haloketones Chloropicrin Regulated Data from the Mills Plant (CA) August DBPs Trihalomethanes 1997 (courtesy of 20% Stuart Krasner) Haloacetonitriles But, the Bad TTHMs 2% Stuff is Chloral Hydrate probably 1% somewhere Unknown Sum of 5 Haloacetic Acids here? TOX 10% Unknown Organic Halogen 64% Bromochloroacetic Acid 3% 21
Cyto- and Geno-Toxicity of DBP classes Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research . (Richardson et al., 2007)
C- and N-based DBPs Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research . (Richardson et al., 2007)
Final disinfectant Drinking water treatment plants usually employ a chemical as a final disinfectant Common oxidative chemicals Free chlorine Chloramines Chlorine dioxide Manganese oxide Potassium permanganate Dave Reckhow - Organics In W & WW
Use of chloramine vs chlorine as final disinfectant Less formation of NOM regulated DBPs Oxidation & Substitution THMs & HAAs (chlorine & chloramines) Hydrolysis and O O O O oxidation is slow R'' C CCl 2 C OH R'' C CCl 2 C R' which minimizes Hydrolysis Hydrolysis further oxidation to O O Hydrolysis & Oxidation TXAA R'' C CHCl 2 Slow DCAA Cl 2 HC C OH Dihalo products, but little trihalo Substitution O (free chlorine only) R'' C CCl 3 Oxidative Hydrolysis Hydrolysis O TCAA THM CHCl 3 Cl 3 C C OH
Use of chloramine vs chlorine as final disinfectant Normalized per micromole of DOC DBP Formation Reactivities of NOM Fractions of a Low-Humic Water” by Hwang, Sclimenti & Krasner
Use of chloramine vs chlorine as final disinfectant Normalized per micromole of DOC DBP Formation Reactivities of NOM Fractions of a Low-Humic Water” by Hwang, Sclimenti & Krasner
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