Disinfectant and disinfectant by- product formation Strategic Exercise Drinking Water
Hans-Peter Kaiser ex Water Works Zurich
Wasserversorgung Content of presentation
. Introduction
. Approach of Water Works Zurich to control disinfectants and disinfectant by-products
. Monitoring drinking water quality
Stadt Zürich Wasserversorgung Page 2 I. Introduction
Ober- Bachs Rorbas Wiesen- Hoch- Dättlikon weningen felden Bülach dangen Nieder- Neer- Pfungen weningen Schöfflis- Höri Embrach Elsau ach Bachen- Winterthur dorf Nieder- bülach Ober- Elgg Schlei- Steinmaur City of Zurich nikon glatt Winkel Embrach Regens- Oberglatt Lufingen Brütten Schlatt Boppelsen bergDielsdorf Otelfingen Nieder- Nürens- Buchs hasli Kloten dorf Kyburg Zell Würenlos Bassers- Dän- Rümlang Lindau Turbenthal Hüttikon dorf - 400 000 inhabitants ikon Regensdorf Opfikon- Dällikon Weisslingen Killwangen Oetwil Glattbrugg Dietli- Illnau- Wild- a.d.L. kon Effretikon Weiningen Wangen- berg Gerolds- Ober- Wallisellen Spreitenbach Untereng- Brüttisellen wil engstringen Russikon Wila stringen Dietikon Dübendorf Volketswil Sternenberg Schlieren Schwerzen- Bergdietikon Zürich Fehraltorf Bauma Urdorf bach Widen Pfäffikon 67 communities Rudolfstetten- Uitikon Fällanden Greifen Hittnau Eggenwil -see Friedlisberg Uster Berikon Birmensdorf See- Zufikon Wettswil Zollikon gräben Bäretswil Oberwil- Aesch Zumikon Lieli a.A. Maur - 506 000 inhabitants Islisberg Stallikon Kilch- Wetzikon Unterlunkhofen Bon- berg Küsnacht Mönch- Arni Adliswil stetten altorf Gossau Oberlunkhofen Rüschli- Erlenbach Hinwil Hedingen kon Jonen Herrliberg Egg Affoltern 2 Thalwil Grüningen a.A. AeugstLangnau Meilen Dürnten - 660 km supply area Ottenbach Uetikon a.A. a.A. Oberrieden Oetwil a.S. a.S. Bubikon Rüti Obfelden Mettmen- Hausen Männe- a.A. Horgen dorf Hombrechtikon stetten Stäfa Masch- Rifferswil wanden Kappel a.A. Wädenswil Knonau Hirzel Cham Richters- Stein- Baar Neuheim Schönen- wil hausen Wollerau berg Hütten Hünenberg Menzingen Zug
Stadt Zürich Wasserversorgung Page 3 Task of the water works Zurich (WVZ)
To supply drinking water and water for fire fighting to the city
– anytime good quality – anytime in sufficient quantity – with sufficient pressure – as cost-efficient as possible
280 employees
Stadt Zürich Wasserversorgung Seite 4 Water treatment plants
Sihlbrugg Spring Water Plant
Lengg Lake Water Plant (250 000 m3/day) Moos Lake Water Plant (80 000 m3/day) Hardhof Groundwater Plant (150 000 m3/day)
Stadt Zürich Wasserversorgung Page 5 Lake water treatment in the Lengg plant
Raw water Oxidation/disinfection with ozone (O3) from lake Zurich
pH adjustment with sodium carbonate (Na2CO3)
Two layer rapid sand filtration
Disinfection with ozone (O3)
Biological activated carbon filtration
Biological activated slow sand filtration
Drinking water
Stadt Zürich Wasserversorgung Page 6 Lake water treatment in the Moos plant
Raw water Oxidation/disinfection with a mixture of from lake Zurich chlorine/chlorine dioxide (Cl2/ClO2)
Flocculation with aluminum sulfate (Al2(SO4)3
Two-layer rapid sand filtration
Disinfection with ozone (O3)
Biological activated carbon filtration
Biological activated slow sand filtration
pH adjustment with sodium hydroxide (NaOH)
Drinking water
Stadt Zürich Wasserversorgung Seite 7 Why disinfection is so important?
Definition of drinking water disinfection Measure to reduce the number of infectious pathogenic microorganisms by inactivation.
Diseases caused by pathogenic microorganisms in drinking water: WHO: Worldwide approx. 2 million illnesses per year and approx. 800000 deaths (600000 children).
But also diseases caused by pathogenic microorganisms in drinking water in the US and Europe:
1993 Milwaukee Wisconsin 400000 sick people (Cryptosporidia) 2010 Östersund, Sweden 27000 sick people (Cryptosporidia) 2015 Le Locle 1000 sick people (Norovirus)
In Europe, the WHO estimates about 14 deaths per day
Stadt Zürich Wasserversorgung 25.03.2018 II. Disinfectants and disinfectant by-products Ozone
Regulated disinfectant and disinfectant by-products (CH: TBDV)
Disinfectant / DBPs Reaction Health effects
Ozone (O3) Ozone is immediately reduced Not considered to be toxic after ingestion. when ingested at concentrations applied in drinking water treatment.
Highly toxic when inhaled - Bromate (BrO3 ) Ozone + Bromide → Bromate carcinogenic, genotoxic (bladder cancer)
DBP: Disinfection By-Product TBDV: Ordinance for drinking water in Switzerland (Verordnung des EDI über Trinkwasser sowie Wasser in öffentlich zugänglichen Bädern und Duschanlagen)
Stadt Zürich Wasserversorgung Page 9 Ozone
Emerging disinfectant by-products DBPs Reaction Health effects
Nitrosoamines Carcinogenic, genotoxic (bladder cancer) NDMA Ozone + N,N-Dimethylsulfamide (DMS; degradation product of the i pesticide Tolylfluanide) →Nitroso- dimethylamine (NDMA) (+NDPA, NMEA), NMOR, NPIP, NPYR, NDBA, NDEA, NDMA) Aldehydes Ozone + NOM Some of them Organic acids carcinogenic, genotoxic (not analyzed at WVZ)
- Iodate (IO3 ) Ozone + Iodide No health effect known (not analyzed at WVZ)
NOM: Natural Organic Matter (DOC/POC: Dissolved/Particulate Organic Carbon)
Stadt Zürich Wasserversorgung Page 11 Ozone - Analytical methods Compound Analytical method Höchst- Guideline LOQ of wert CH value WHO WVZ Regulated compounds (TBDV) Ozone -Amperometry (cont.) 50 µg/L - 0.02 mg/L -Indigo method i 0.01 mg/L (DEV G3/DIN 38408 part 3) - Bromate (BrO3 ) IC (post-column derivatization) 10 µg/L 10 µg/L 0.5 µg/L (WVZ-method, Salhi et al. (1999), Wat. Res. 33: 3239-45)
Emerging disinfection by-products Nitrosamines SPE LC HRMS - 100 ng/L 2-5 ng/L
(8 compounds) (WVZ method, Kraus et al. (BRDproposed: (2008) Anal. Chem. 80: 834-842 10 ng/L) N,N-dimethyl- LC MS/MS - - 24 ng/L sulfamide (WVZ method)
DEV: Deutsche Einheitsverfahren (usually also DIN/EN/ISO norms) LOQ: Limit of Quantification WVZ: Water Works Zurich Stadt Zürich Wasserversorgung Page 13 Chlorine
Regulated disinfectant and disinfectant by-products (CH: TBDV)
Disinfectant / DBPs Reaction Health effects
Chlorine Chlorine (hypochlorous Not considered to be toxic acid / hypochlorite) is when ingested at immediately reduced after concentrations applied in ingestion. drinking water treatment
Toxic when inhaled
Trihalomethanes (THMs) Chlorine (bromine) + NOM carcinogenic and partly (CHCl3, CHBrCl2, CHBr2Cl, genotoxic CHBr3)
Stadt Zürich Wasserversorgung Page 14 Chlorine
Emerging disinfectant by-products DBPs Reaction Health effects
Haloacetic acids Chlorine (iodine, bromine) + NOM carcinogenic and or genotoxic Halonitromethanes ditto genotoxic Iodo-trihalomethanes ditto cytotoxic
Halofuranones (MX) i ditto genotoxic and carcinogenic Haloamides ditto genotoxic Haloacetonitriles ditto genotoxic Haloaldehydes (Di- and ditto genotoxic Trichloracetaldehyde) 2,4,6-trichlorophenol ditto possibly carcinogenic
Stadt Zürich Wasserversorgung Page 16 Chlorine - Analytical methods
Compound Analytical method Höchstwert Guideline LOQ of CH value WHO WVZ Regulated compounds (TBDV) Chlorine Amperometry 100 µg/L 5000 µg/L 0.02 mg/L (continuous)
DPD method 0.01mg/L (DEV G4-2, EN ISO 7393-2) Trihalomethanes HS SPME GC/MS 50 µg/L - 0.5 µg/L (THM) (DIN 38407-41)
Chloroform 0.3 mg/L Bromdichlormethane 0.06 mg/L Chlordibromomethane 0.1 mg/L Bromoform 0.1 mg/L
HS: Head Space SPME: Solid Phase MicroExtraction
Stadt Zürich Wasserversorgung Page 17 Chlorine - Analytical methods
Compound Analytical WHO Guideline LOD reported method value proposed Emerging disinfection by-products (not analyzed at WVZ)
Mono, di- and trichloroacetic acid GC(ECD) after 20/50/200 µg/L 12-17 ng/L esterification EPA Method 552.1 Halonitromethanes SPME GC-MS1 - 1-50 ng/L (trichloronitromethane, chloropicrin) Iodo-trihalomethanes SPME GC-MS1 - 1-50 ng/L Halo acetonitrils SPME GC-MS1 1-50 ng/L (Dichloro-/Dibromoacetonitrile) 20 µg/L/70µg/L Haloamides GC-MS/MS - 0.1-0.3 µg/L after liquid/liquid extraction2 1: Luo et al., J. Chromatogr. A 1365 (2014). EPA: US Environmental Protection Agency 2: Templeton et al., Report of project DWI 70/2/268 (2012). LOD: Limit of Detection SPME: Solid Phase MicroExtraction
Stadt Zürich Wasserversorgung Page 18 Chlorine - Analytical methods
Compound Analytical method WHO Guideline LOD proposed value reported Emerging disinfection by-products (not measured at WVZ)
Halofuranones (MX compounds) LC ESI MS/MS after -* 7-35 ng/L liquid/liquid extraction1 Haloaldehydes (Di- and GC MS2 or -* 0.5 µg/L Trichloroacetaldehyde) GC(ECD) 2,4,6-trichlorophenol GC MS 200 µg/L 5 µg/L (EPA method 604)
1 Padilla (2015),, thesis University of Washington. * WHO: Concentrations well below those of health concern 2 Jeong et al. (2015), Environ. Sci. Technol. 49: 13749-59 ESI: ElectroSpray Ionization
Stadt Zürich Wasserversorgung Page 19 Chlorination disinfectant by-products
Source: Barcelo, Emerging Organic Contaminants, Springer 2012
Stadt Zürich Wasserversorgung 25.03.2018 Chlorine dioxide Regulated disinfectants and disinfectant by-products (CH: TBDV)) Disinfectant / DBPs Reaction Health effects
Chlorine dioxide (ClO2) Chlorine dioxide is instantly Not considered to be toxic reduced to chlorite and when ingested at chloride after ingestion. concentrations applied in drinking water treatment
Toxic when inhaled - Chlorite (ClO2 ) Chlorine dioxide + NOM Changes in red blood cells - Chlorate (ClO3 ) Disproportion of chlorite to Changes in thyroid histology chlorine dioxide and an thyroid hormones chlorate Changes in red blood cells (Formation of chlorate in hypochlorite solutions after long storage times) Emerging disinfectant by-products: None under evaluation
Stadt Zürich Wasserversorgung Page 21 Chlorine dioxide - Analytical methods
Compound Analytical method Höchstwert WHO Guideline LOQ CH value WVZ
Regulated compounds (TBDV) Chlorine dioxide Amperometry 50 µg/L - 10 µg/L (continuous)
DPD 20 µg/L (DEV G5 DIN 38408-5)
TMB 2 µg/L (Hach-Lange method) Chlorite IC (DEV D25/D20) 200 µg/L 700 µg/L 6 µg/L Chlorate IC (DEV D25/D20) 200 µg/L 700 µg/L 6 µg/L
DPD: N,N-diethyl-p-phenylenediamine TMB: : 3,3′,5,5′-tetramethylbenzidine
Stadt Zürich Wasserversorgung Page 22 How to control disinfectant by-product formation
Lab analysis are spot tests: Monthly, a 100 µL to 100 mL sample is analyzed. In the same period, the Lengg plant produces 3 billion L of drinking water.
Amount of DBP formed depends mainly on the concentrations of the precursor and the disinfectant.
Approach to control the formation of disinfectant by-products: Measuring the variation of the concentration of precursors in lake Zurich (bromine, NOM) minor variation Control the disinfection process based on continuous measurements in a way to never exceed a defined maximum disinfectant concentration The formation of DBPs is limited at anytime
Stadt Zürich Wasserversorgung Page 23 Lengg: Sampling locations and frequency
pH- adjustment Ozone (cont.) Ozone (cont.) Bromate (m) NDMA (q) Bromide (m) Rapid filtration Ozone Slow sand NOM (m) Clean water filtration Bromate (m) Ozonation reservoir NDMA (q) Pre-ozonation Ozone Lake Zurich Ozone (cont.) Ozone (cont.) Activated Pumping Pumping Bromate (m) carbon station filtration station NDMA (q) to the reservoirs
Bromate (m) (cont.): continuous NDMA (q) (m): monthly (q): quarterly
Stadt Zürich Wasserversorgung Page 24 Moos: Sampling locations and frequency
Ozone (cont.) pH-adjustment (NaOH) Aluminium THM (m) -sulfate Ozone Slow sand Chlorite (m) Clean water Flocculation filtration Chlorate (m) Rapid reservoir filtration Ozonation Activated Chlorine (cont.) carbon filtration Pumping Lake Zurich Pumping station to the station reservoirs Chlorination Bromide (q) (Cl2/ClO2) Bromate (q) (cont.): continuous NDMA (q) Bromide (q) (m): monthly THM (m) NOM (m) (q): quarterly Chlorite (m) Bromate (q) Chlorate (m) NDMA (q)
Stadt Zürich Wasserversorgung Seite 25 Summary and Outlook
• With chlorine a wide variety of disinfection by-products are formed. • Chlorine dioxide is degraded to chlorite, chlorate and chloride. • With ozone, bromate and many other DBPs are formed. → Too many DBPs to analyse them all
→ Bioassays of water before and after disinfection (Ames microplate fluctuation test Ames-MPF, bioassays with Daphnia,Thamnocephalus
→ Replacing the chlorine/chlorine dioxide step in the Moos plant to reduce DBPs in drinking water
New Moos treatment chain: NaOH
Activated Pre- Ultra- UV- Drinking Lake Ozonation carbon filtration filtration disinfection water Zurich filtration
Stadt Zürich Wasserversorgung Page 26 III Quality monitoring at water works Zurich
Quality Control with 25 employees (ISO 17025)
Stadt Zürich Wasserversorgung Page 27 Chemical parameters
• Temperature, pH el. conductivity • Water constituents (Ca, Mg, nitrate, etc. • 30 metals and other elements (ICP-MS), • UV-absorbance 254 nm • NOM (DOC, POC, TOC) • Bromate, chlorate, chlorite ICP-MS : Inductively coupled plasma - mass spectrometry
Micropollutants • Pesticides (approx. 50) • Pharmaceuticals (approx. 40) • Volatile org. carbon (approx. 40, VOC; DBPs) • Polychlorinated biphenyls (PCB) • Fuel additives and solvents • Complexing agents (NTA, EDTA) • Fluorinated hydrocarbons • Artificial sweeteners (Acesulfam) • Odours and flavours
Stadt Zürich Wasserversorgung Seite 28 Microbiological and limnological parameters
In addition to the chemical monitoring parameters, microbiological and linmological monitoring is essential for water works Zurich.
Parameters: • Heterotrophic plate counts (HPC; cfu) • E.coli (fecal indicator) • Enterococcus (fecal indicator)
• Algae • Plankton
• Total cell counts (flow cytometry)
Stadt Zürich Wasserversorgung Page 29 III Quality Control
Stadt Zürich Wasserversorgung Seite 30 Continuous online monitoring
Physical-chemical parameters (temperature, pH, redox potential, turbidity, particles, conductivity, UV-absorbance, fluorescence, residuals of disinfectants)
Stadt Zürich Wasserversorgung Seite 31 Early warning system with bio sensors
Sensitive organisms, like Daphnia sp. to detect poisonous compounds after chemical accidents or sabotage.
Stadt Zürich Wasserversorgung Seite 32 Daphnia test
Stadt Zürich Wasserversorgung Seite 33 Zurich’s drinking water is safe at any time!
Thank you for your attention
www.zueriwasser.ch
Stadt Zürich Wasserversorgung Page 34