Wasserversorgung Disinfectant and disinfectant by- product formation Strategic Exercise Drinking Water Hans-Peter Kaiser ex Water Works Zurich
Wasserversorgung
Disinfectant and disinfectant by-
product formationStrategic Exercise Drinking Water
Hans-Peter Kaiserex Water Works Zurich
Stadt Zürich
Wasserversorgung Page 2
Content of presentation
Introduction
Approach of Water Works Zurich to control disinfectants
and disinfectant by-products
Monitoring drinking water quality
Stadt Zürich
Wasserversorgung Page 3
City of Zurich
- 400 000 inhabitants
67 communities
- 506 000 inhabitants
- 660 km2 supply area
I. Introduction
Zürich
Bachs Hoch-
felden Bülach
Rorbas
Uitikon
Killwangen
Embrach
Dättlikon
Pfungen
Wiesen-
dangen
Elsau
Elgg
Schlatt
ZellKyburgTurbenthal
Wila
Sternenberg
WeisslingenWild-
berg
Russikon
Fehraltorf Bauma
PfäffikonHittnau
Bäretswil
Wetzikon
HinwilGossau
Rüti
Dürnten
Bubikon
Egg
Hombrechtikon
Mönch-
altorf
Grüningen
Stäfa
Oetwil a.S.Meilen
Herrliberg
Ober-
EmbrachBrütten
Lindau
WinterthurHöri
Nieder-
weningen
Ober-
weningen
Rümlang
KlotenNürens-
dorf
Lufingen
Bachen-
bülach
Winkel
Bassers-
dorfOpfikon-
Glattbrugg
Wallisellen
Illnau-
Effretikon
Dietli-
kon
Uster
See-
gräben
Volketswil
Wangen-
Brüttisellen
Dübendorf
Greifen
-see
Schwerzen-
bachFällanden
MaurZumikon
Zollikon
Wädenswil
Horgen
Hirzel
Wollerau
Hütten
Schönen-
berg
Menzingen
Baar Neuheim
Thalwil
Kappel a.A.
Hausen
a.A.
Rifferswil
Zug
ChamStein-
hausen
Hünenberg
Masch-
wanden
Knonau
Obfelden
Ottenbach
Mettmen-
stetten
Langnau
a.A.
Aeugst
a.A.
Richters-
wil
Uetikon
a.S.
Affoltern
a.A.
Adliswil
Hedingen
Bon-
stetten
Stallikon
Arni
Jonen
IslisbergUnterlunkhofen
Oberlunkhofen
Zufikon
Berikon
Oberwil-
Lieli
Wettswil
a.A.Aesch
Birmensdorf
Oberglatt
Nieder-
glatt
Eggenwil
WidenRudolfstetten-
Friedlisberg
Urdorf
Schöfflis-
dorf
Neer-
ach
Steinmaur
Dielsdorf
Buchs
Regens-
berg
Schlei-
nikon
Boppelsen
Nieder-
hasli
RegensdorfDän-
ikon
Würenlos
Otelfingen
Hüttikon
Ober-
engstringen
Schlieren
Weiningen
Untereng-
stringen
Gerolds-
wil
Oetwil
a.d.L.
Spreitenbach
Dietikon
Bergdietikon
Dällikon
Küsnacht
Oberrieden
Rüschli-
kon
Kilch-
berg
Männe-
dorf
Erlenbach
Stadt Zürich
Wasserversorgung Seite 4
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 Page 5
Lengg
Lake Water Plant
(250 000 m3/day)
Sihlbrugg
Spring Water Plant
Moos
Lake Water Plant
(80 000 m3/day)
Hardhof
Groundwater Plant
(150 000 m3/day)
Water treatment plants
Stadt Zürich
Wasserversorgung Page 6
Lake water treatment in the Lengg plant
Raw water
from lake ZurichOxidation/disinfection with ozone (O3)
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 Seite 7
Lake water treatment in the Moos plant
Raw water
from lake Zurich
Oxidation/disinfection with a mixture of
chlorine/chlorine dioxide (Cl2/ClO2)
pH adjustment with sodium hydroxide (NaOH)
Two-layer rapid sand filtration
Disinfection with ozone (O3)
Biological activated carbon filtration
Biological activated slow sand filtration
Drinking water
Flocculation with aluminum sulfate (Al2(SO4)3
Stadt Zürich
Wasserversorgung
Why disinfection is so important?
Definition of drinking water disinfectionMeasure 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
25.03.2018
Stadt Zürich
Wasserversorgung Page 9
Regulated disinfectant and disinfectant by-products (CH: TBDV)
Disinfectant / DBPs Reaction Health effects
Ozone (O3) Ozone is immediately reduced
after ingestion.
Not considered to be toxic
when ingested at
concentrations applied in
drinking water treatment.
Highly toxic when inhaled
Bromate (BrO3-) Ozone + Bromide → Bromate carcinogenic, genotoxic
(bladder cancer)
II. Disinfectants and disinfectant by-products
Ozone
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 11
Emerging disinfectant by-products
DBPs Reaction Health effects
Nitrosoamines
NDMA
(+NDPA, NMEA),
NMOR, NPIP, NPYR,
NDBA, NDEA, NDMA)
Ozone + N,N-Dimethylsulfamide
(DMS; degradation product of the
pesticide Tolylfluanide) →Nitroso-
dimethylamine (NDMA)
Carcinogenic, genotoxic
(bladder cancer)
Aldehydes
Organic acids(not analyzed at WVZ)
Ozone + NOM Some of them
carcinogenic, genotoxic
Iodate (IO3-)
(not analyzed at WVZ)
Ozone + Iodide No health effect known
Ozone
i
NOM: Natural Organic Matter (DOC/POC: Dissolved/Particulate Organic Carbon)
Stadt Zürich
Wasserversorgung Page 13
Compound Analytical method Höchst-
wert CH
Guideline
value WHO
LOQ of
WVZ
Regulated compounds (TBDV)
Ozone -Amperometry (cont.)
-Indigo method(DEV G3/DIN 38408 part 3)
50 µg/L - 0.02 mg/L
0.01 mg/L
Bromate (BrO3-) IC (post-column derivatization)
(WVZ-method, Salhi et al.
(1999), Wat. Res. 33: 3239-45)
10 µg/L 10 µg/L 0.5 µg/L
Emerging disinfection by-products
Nitrosamines(8 compounds)
SPE LC HRMS(WVZ method, Kraus et al.
(2008) Anal. Chem. 80: 834-842
- 100 ng/L(BRDproposed:
10 ng/L)
2-5 ng/L
N,N-dimethyl-
sulfamide
LC MS/MS(WVZ method)
- - 24 ng/L
Ozone - Analytical methods
i
DEV: Deutsche Einheitsverfahren (usually also DIN/EN/ISO norms)
LOQ: Limit of Quantification
WVZ: Water Works Zurich
Stadt Zürich
Wasserversorgung Page 14
Chlorine
Disinfectant / DBPs Reaction Health effects
Chlorine Chlorine (hypochlorous
acid / hypochlorite) is
immediately reduced after
ingestion.
Not considered to be toxic
when ingested at
concentrations applied in
drinking water treatment
Toxic when inhaled
Trihalomethanes (THMs) (CHCl3, CHBrCl2, CHBr2Cl,
CHBr3)
Chlorine (bromine) + NOM carcinogenic and partly
genotoxic
Regulated disinfectant and disinfectant by-products (CH: TBDV)
Stadt Zürich
Wasserversorgung Page 16
Chlorine
DBPs Reaction Health effects
Haloacetic acids Chlorine (iodine, bromine) + NOM carcinogenic and or
genotoxic
Halonitromethanes ditto genotoxic
Iodo-trihalomethanes ditto cytotoxic
Halofuranones (MX) ditto genotoxic and carcinogenic
Haloamides ditto genotoxic
Haloacetonitriles ditto genotoxic
Haloaldehydes (Di- and
Trichloracetaldehyde)
ditto genotoxic
2,4,6-trichlorophenol ditto possibly carcinogenic
Emerging disinfectant by-products
i
Stadt Zürich
Wasserversorgung Page 17
Compound Analytical method Höchstwert
CH
Guideline
value WHO
LOQ of
WVZ
Regulated compounds (TBDV)
Chlorine Amperometry
(continuous)
DPD method(DEV G4-2,
EN ISO 7393-2)
100 µg/L 5000 µg/L 0.02 mg/L
0.01mg/L
Trihalomethanes
(THM)
Chloroform
Bromdichlormethane
Chlordibromomethane
Bromoform
HS SPME GC/MS (DIN 38407-41)
50 µg/L -
0.3 mg/L
0.06 mg/L
0.1 mg/L
0.1 mg/L
0.5 µg/L
Chlorine - Analytical methods
HS: Head Space SPME: Solid Phase MicroExtraction
Stadt Zürich
Wasserversorgung Page 18
Chlorine - Analytical methods
Compound Analytical
method
proposed
WHO Guideline
value
LOD reported
Emerging disinfection by-products (not analyzed at WVZ)
Mono, di- and trichloroacetic acid GC(ECD) after
esterificationEPA Method 552.1
20/50/200 µg/L 12-17 ng/L
Halonitromethanes
(trichloronitromethane, chloropicrin)
SPME GC-MS1 - 1-50 ng/L
Iodo-trihalomethanes SPME GC-MS1 - 1-50 ng/L
Halo acetonitrils
(Dichloro-/Dibromoacetonitrile)
SPME GC-MS1
20 µg/L/70µg/L
1-50 ng/L
Haloamides GC-MS/MS after liquid/liquid
extraction2
- 0.1-0.3 µg/L
1: Luo et al., J. Chromatogr. A 1365 (2014). EPA: US Environmental Protection Agency2: Templeton et al., Report of project DWI 70/2/268 (2012). LOD: Limit of Detection
SPME: Solid Phase MicroExtraction
Stadt Zürich
Wasserversorgung Page 19
Chlorine - Analytical methods
Compound Analytical method
proposed
WHO Guideline
value
LOD
reported
Emerging disinfection by-products (not measured at WVZ)
Halofuranones (MX compounds) LC ESI MS/MS after
liquid/liquid extraction1
-* 7-35 ng/L
Haloaldehydes (Di- and
Trichloroacetaldehyde)
GC MS2 or
GC(ECD)
-* 0.5 µg/L
2,4,6-trichlorophenol GC MS (EPA method 604)
200 µg/L 5 µg/L
* WHO: Concentrations well below those of health concern
ESI: ElectroSpray Ionization
1 Padilla (2015),, thesis University of Washington.2 Jeong et al. (2015), Environ. Sci. Technol. 49: 13749-59
Stadt Zürich
Wasserversorgung
Chlorination disinfectant by-products
25.03.2018
Source: Barcelo, Emerging Organic Contaminants, Springer 2012
Stadt Zürich
Wasserversorgung Page 21
Chlorine dioxide
Emerging disinfectant by-products: None under evaluation
Disinfectant / DBPs Reaction Health effects
Chlorine dioxide (ClO2) Chlorine dioxide is instantly
reduced to chlorite and
chloride after ingestion.
Not considered to be toxic
when ingested at
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
chlorine dioxide and
chlorate(Formation of chlorate in
hypochlorite solutions after long
storage times)
Changes in thyroid histology
an thyroid hormones
Changes in red blood cells
Regulated disinfectants and disinfectant by-products (CH: TBDV))
Stadt Zürich
Wasserversorgung Page 22
Chlorine dioxide - Analytical methods
Compound Analytical method Höchstwert
CH
WHO Guideline
value
LOQ
WVZ
Regulated compounds (TBDV)
Chlorine dioxide Amperometry
(continuous)
DPD(DEV G5 DIN 38408-5)
TMB(Hach-Lange method)
50 µg/L - 10 µg/L
20 µg/L
2 µg/L
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 23
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 24
Lengg: Sampling locations and frequency
Rapid filtration
Pre-ozonation
Ozonation
Activated
carbon
filtration
Pumping
station
Clean water
reservoir
to the
reservoirs
pH-
adjustment
Pumping
station
Lake Zurich
Slow sand
filtration
Ozone
Ozone
Ozone (cont.)
Bromide (m)
NOM (m)
Bromate (m)
NDMA (q)
Ozone (cont.)
Bromate (m)
NDMA (q)
Bromate (m)
NDMA (q)
Ozone (cont.)
Ozone (cont.)
Bromate (m)
NDMA (q)
(cont.): continuous
(m): monthly
(q): quarterly
Stadt Zürich
Wasserversorgung Seite 25
Moos: Sampling locations and frequency
Rapid
filtration
Chlorination
(Cl2/ClO2)
Ozonation
Activated
carbon
filtrationPumping
station
Clean water
reservoir
to the
reservoirs
pH-adjustment
(NaOH)
Pumping
stationLake Zurich
Slow sand
filtration
Ozone
Chlorine (cont.)
Bromide (q)
Bromate (q)
NDMA (q)
THM (m)
Chlorite (m)
Chlorate (m)
Ozone (cont.)
(cont.): continuous
(m): monthly
(q): quarterly
THM (m)
Chlorite (m)
Chlorate (m)Flocculation
Aluminium
-sulfate
Bromide (q)
NOM (m)
Bromate (q)
NDMA (q)
Stadt Zürich
Wasserversorgung Page 26
• 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:
Summary and Outlook
Pre-
filtrationLake
Zurich
Ultra-
filtrationOzonation
Activated
carbon
filtration
UV-
disinfection
NaOH
Drinking
water
Stadt Zürich
Wasserversorgung Page 27
III Quality monitoring at water works Zurich
Quality Control with 25 employees
(ISO 17025)
Stadt Zürich
Wasserversorgung Seite 28
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
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
ICP-MS : Inductively coupled plasma - mass spectrometry
Stadt Zürich
Wasserversorgung Page 29
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 Seite 31
Continuous online monitoring
Physical-chemical parameters (temperature, pH, redox potential, turbidity,
particles, conductivity, UV-absorbance, fluorescence, residuals of disinfectants)
Stadt Zürich
Wasserversorgung Seite 32
Early warning system with bio sensors
Sensitive organisms, like Daphnia sp. to detect poisonous compounds
after chemical accidents or sabotage.
Stadt Zürich
Wasserversorgung Seite 33
Daphnia test
Stadt Zürich
Wasserversorgung Page 34
Zurich’s drinking water
is safe at any time!
Thank you for your
attention
www.zueriwasser.ch