Disinfection and disinfection byproducts...USEPA Stage 1 D/DBP Rule USEPA Stage 2 D/DBP Rule WHO...

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Disinfection and disinfection byproducts

YANG XinDepartment of Environmental Science

Sun Yat-sen University2018.4

Guangzhou

Hong Kong

2

4

River

PumpingDisinfection

Filtration Sedimentation Flocculation Coagulation

Pumping

Storage Neighborhood

Add Fluoride

Typical Water Treatment System

Pre-oxidation

5

Major Water Quality Indicators

n Microorganismsn Inorganic Chemicals n Disinfectants & Disinfection Byproductsn Organic Chemicals

7

Origins of “Contamination”

n Contaminant: Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil.

n Naturally occurringn Point-source (end-of-

pipe)n Non-point source

(agricultural, land use)

9

Focus today

n Disinfection processesq Cl2, NH2Cl, O3, ClO2, UV

n Disinfection byproducts

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Disinfection

Disinfectionn Water or wastewater processes for controlling

microbial contaminants to prevent the transmission of waterborne disease through the infection by pathogenic microorganisms.

n Necessity of disinfection (disinfection credits): Giardia lamblia

Removals Virus

Removals

Filter Process

Maximum Turbidity

(NTU) (log) (%) (log) (%)

Conventional: coagulation, flocculation, sedimentation, rapid rate (granular) filtration

0.5

2.5

99.3

2.0

99.0

Direct filtration: coagulation, rapid rate (granular) filtraton 0.5 2.0 99.0 1.0 90.0

Slow sand filtration 1.0 2.0 99.0 2.0 99.0 Diatomaceous earth filtration 1.0 2.0 99.0 1.0 90.0 Total (including disinfection) -- 3.0 99.9 4.0 99.99 Source:EPA, 1989.

Particulate Impurities in Water

0.10.001 0.01 100 101.00.0001 Size (m)

Flocculated particles

Dissolved particles

Suspended particles

Colloids

Protozoan

Bacteria

Algae

Organic molecules

Dissolve ionsViruses

SETTLING

Enough?

Sand FilterPost-filtered particles

Need Disinfection

Disinfection

Ideal disinfectants

Disinfection methodsn Most common candidates in practice:

q Chlorination

q Chloramination

q ClO2

q Ozonation

q UV-radiation

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Free Chlorine - Background and Historyn Considered to be first used in 1905 in Londonn Reactions for free chlorine formation:

Cl2 (g) + H2O <=> HOCl + H+ + Cl-HOCl <=> H+ + OCl-

n Chemical forms of free chlorine: Cl2 (gas), NaOCl (liquid), or Ca(OCl)2 (solid)

n Has been the “disinfectant of choice” in US until recently.n recommended maximum residual concentration of free chlorine < 5

mg/L (by US EPA)n Concerns about the toxicity of free chlorine disinfection by-products

(trihalomethanes and other chlorinated organics)

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Monochloramine - History and Backgroundn First used in Ottawa, Canada and Denver, Co. (1917)n Became popular to maintain a more stable chlorine residual and

to control taste and odor problems and bacterial re-growth in distribution system in 1930’s

n Decreased usage due to ammonia shortage during World War IIn Increased interest in monochloramine:

q alternative disinfectant to free chlorine due to low THM potentials

q more stable disinfectant residual; persists in distribution system

q secondary disinfectant to ozone and chlorine dioxide disinfection to provide long-lasting residuals

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Ozone n First used in 1893 at Oudshoonn Used in 40 WTPs in US in 1990 (growing use since then), but more

than 1000WTPs in European countriesn Increased interest as an alternative to free chlorine (strong oxidant;

strong microbiocidal activity; perhaps less toxic DBPs) q A secondary disinfectant giving a stable residual may be needed

to protect water after ozonation, due to short-lasting ozone residual.

n Colorless gas; relatively unstable; reacts with itself and with OH- in water; less stable at higher pH

n Formed by passing dry air (or oxygen) through high voltage electrodes to produce gaseous ozone that is bubbled into the water to be treated.

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Chlorine Dioxide

n First used in Niagara Fall, NY in 1944 to control phenolic tastes and algae problems

n Used in 600 WTP (84 in the US) in 1970’s as primary disinfectant and for taste and odor control

n Very soluble in water; generated as a gas or a liquid on-site, usually by reaction of Cl2 gas with NaClO2 :q 2 NaClO2 + Cl2 2 ClO2 + 2 NaCl

n Usage became limited after discovery of it’s toxicity in 1970’s & 1980’s q thyroid, neurological disorders and anemia in experimental animals by

chloraten Recommended maximum combined concentration of chlorine dioxide

and it’s by-products < 0.5 mg/L (by US EPA in 1990’s)

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Ultraviolet Radiation and Effects

n Physical processn Energy absorbed by

DNAn Inhibits replicationn Pyrimidine Dimersn Strand Breaksn Other Damage

ACGTAAC

TT A

G

G C

T

UV

DNA

21Disinfection

Simple Solar Disinfection

22Disinfection 22

Solar Disinfection

Inactivation mechanisms

Disinfection Kinetics and Dose Concept n Chick-Watson’ law:

where = coefficient of specific lethality. C = concentration of chemical disinfectant.

I = intensity of physical disinfectant. n = empirical constant (frequently 1).Thus,

If n = 1 and assigning Ct (or It) = dose,

NIorCdtdN n)]([

tIorCNN n

o

)]([ln

doseNN

o

ln dose')kill(logNN

logo

or

Ln (N

/No)

Dose

Slope = -

dose')kill(logNN

logo

In reality: (Why?)

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Inactivation of Cryptosporidium Oocysts in Water by Chemical Disinfectants

Disinfectant CT99 (mg-min/L) Reference

Free Chlorine 7,200+ Korich et al., 1990Monochloramine 7,200+ Korich et al., 1990Chlorine Dioxide >78 Korich et al., 1990Mixed oxidants <120 Venczel et al., 1997Ozone ~3-18 Finch et al., 1994

Korich et al., 1990Owens et al., 1994

C. parvum oocysts inactivated by low doses of UV radiation: <10 mJ/cm2

DBPs

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chlorine

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Disinfection Byproducts (DBPs)

DBP Formation and Control

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Reactions with Chlorine

HOCl + natural organics (NOM)

Oxidized NOMand inorganic chloride

•Aldehydes

Chlorinated Organics•TOX•THMs•HAAs

The Precursors!

n MCL is 0.080 mg/L (stage 1)

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The Haloacetic Acids

(HAA5 = sum of monochloro, dichloro, trichloro, monobromo, and dibromo)

n MCL for HAA5 is 0.060 mg/L (stage 1)

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Haloacetonitriles

n Not regulated, but measured with THMs

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Halopropanones

n Also not regulated, but measured with THMs

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© Known occurrence in California and Colorado from rocket fuel processing.

© Suspected to be a disinfection by-product.

© Significant carcinogenicity at extremely low concentrations,with a 10 -6 cancer risk at aconcentration of 0.7 ng/L.

© Expected to be on EPA’s CCL 3.

Nitrosamines

NDMAN

CH3

CH3

NO

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TOX: Known & Unknown

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History

HAAsHANs

WHO guideline 1993

THMs

THM Rule

CNCl

19701980 1990 2000 2010

TOX

TOCl TOBr

NDMABr-DBPs

I-DBPsN-DBPs

USEPA Stage 1 D/DBP Rule

USEPA Stage 2 D/DBP RuleWHO guideline 2006

WHO guideline 2008

Shang, C. (2007) Formation of Disinfection By-Products from Alternative Disinfection Processes. International Workshop on the Security and Sustainability of Water Supply Systems.

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The DBP IcebergDHAAs

THMs, THAAs

Halogenated Compounds

Non-halogenated Compounds

~700 Known DBPs

50 MWDSC DBPs

ICR Compounds

Stuart Krasner

David A. Reckhow, Reactivity of organic nitrogen and formation of nitrogenous DBPs, AWWA Annual Conference, Anahelm, 2003.

Susan Richardson

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Muellner, M.G., Wagner, E.D., McCalla, K., Richardson, S.D., Woo, Y.T., Plewa, M.J. (2007)Environ. Sci. Technol.; 41(2) pp 645 - 651

N-DBPs are more toxic.

N-DBPs

Muellner et al., Environ. Sci. Technol. 2007, 41, 645

NDMA

HAN

HNM

CNX

CH CCl

NCl

C N+

Cl

ClCl

O-

O

Cl C N

N NH3C

OH3C

Nitrogenous DBPs

C-DBPs

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River

PumpingDisinfection

Filtration Sedimentation Flocculation Coagulation

Pumping

Storage Neighborhood

Add Fluoride

Typical Water Treatment System

Pre-oxidation

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Disinfectant

n Chlorine n Chloramine n Chlorine dioxiden UVn Ozone

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NH2Cl vs. Cl2SRNOM: 5 mg/L as DOC NH2Cl or Cl2: 8 mg/L as Cl2 pH = 7.5 Reaction time: 0.5 hr – 7 days

Time (hr)0 20 40 60 80 100 120 140 160 180

Concentration (g/L)

0

5

10

15

20

25

30

35

40

chloroform1,1-DCPDCAN1,1,1-TCPchloropicrin

Time (hr)0 20 40 60 80 100 120 140 160 180

Concentration (g/L)

2

4

6

8

10

chloroform1,1-DCPDCANCNClChloropicrin

NH2Cl Cl2

Yang et al., 2007, Water Research, 41(6), 1193-1200.

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Lab Studies: Chlorine/Monochloramine Mediated Formation of NDMA

(CH3)2 NH + NH2Cl (CH3)2NNO DMA Monochloramine NDMA

HOCl + NH3 NH2Cl + H2Ofree chlorine ammonia monochloramine

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AWWA/WEF Occurrence Study(Distribution System Samples)

Chloramines Free Chlorine

NDMA Concentration (Nanograms/Liter)

0

5

10

15

20

25

30

n = 50 for samples with chloramine residuals n = 29 for samples with free-chlorine residuals

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Chloramination of NOM isolates

n Solution preparation: q Stock solutions were prepared from reagent grade chemicals

with ultrapure water.n NOM fractionation: XAD-8/4 resins

q Hydrophobic acid (HPOA)q Transphilic acid (TPIA)q Hydrophobic neutral (HPON)q Transphilic neutral (TPIN)

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Filtration through 25 m and 0.9 m Balston glass fiber cartridge filters

Adjust filtrate pH to 2.0 with HCl

XAD-8 resinK0.5r’=50

XAD-4 resinK0.5r’=50

1. Desorb with 0.1 N NaOH

MSC cation-exchange resin

Freeze-dry to isolatehydrophobic acids (HPOA)

2. Rinse with DI water, desorb with 75% acetonitrile/25% water

Vacuum evaporate acetonitrile, freeze-dry to isolate hydrophobic neutrals (HPON)

3. Desorb with 0.1 N NaOH

MSC cation-exchange resin

Freeze-dry to isolatetransphilic acids (TPIA)

4. Rinse with DI water, desorb with 75% acetonitrile/25% water

Vacuum evaporate acetonitrile, freeze-dry to isolate transphilic neutrals (TPIN)

Hydrophilic DOM (HPI)

Water sample

NOM Isolation Summary

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DBPs vs. TOX

Yang et al., 2008, Water Research, 42(8-9), 2329-2339.

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SUVA vs. DBPs, TOX

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DON/DOC vs. N-DBPs

DON/DOC (mg N/mg C)0.00 0.02 0.04 0.06 0.08 0.10

DBP yield (nmol/mg C)

0

20

40

60

80

100DCANChloropicrinCNCl

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DON + NH2Cl = N-DBPs

15NH4Cl + Cl2 = 15NH2Cl

DON 15NH2Cl+

15N-DBPs{

14N-DBPs

Nitrogen source

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Analytical method

N

ClEI

N

Cl

ClDichloroacetonitrile

CI

m/z=74

N+O-O

Cl

Cl

Cl

trichloronitromethane

m/z=46

N+O-O

Yang X., et al. (2010) Water Research, 44，2691-2702.

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30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2400

100000

200000

300000

400000

500000

600000

700000

800000

900000

m/z-->

Abundance

Scan 94 (4.431 min): ZD009.D\data.ms35.1

117.0

82.166.1 235.0131.9

30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 2400

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

550000

600000

650000

700000

750000

800000

m/z-->

Abundance

Scan 92 (4.413 min): ZD008.D\data.ms35.2

117.0

82.162.0 235.0133.0

46

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Tyrosine+15NH2Cl=15N-TCNM(mainly)

Tyrosine+14NH2Cl=14N-TCNM

Cl

NO2

CCl3

N+O-O

Cl

Cl

Cl

trichloronitromethane

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tyrosineN14 #129 RT: 5.01 AV: 1 NL: 8.52E7T: + c Full ms [ 40.00-500.00]

50 60 70 80 90 100 110 120m/z

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Relative

Abunda

nce

73.9

81.8

83.8

75.9

72.9

85.9

107.876.957.0 110.969.961.955.0 86.963.9 93.0 95.9 116.8105.0

tyrosineN15 #130 RT: 5.03 AV: 1 NL: 3.94E7T: + c Full ms [ 40.00-500.00]

50 60 70 80 90 100 110 120m/z

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Relativ

e Abun

dance

74.9

81.8

83.8

76.9

72.9

85.957.0 108.877.955.0 58.9 111.869.8 86.964.9 92.9 118.895.9 105.1

Tyrosine+14NH2Cl=14N-DCAN

Tyrosine+15NH2Cl=15N-DCAN(mainly)

N

Cl

ClDichloroacetonitrile

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15N-TCNM and 15N-DCAN

Compounds Dosage (mmol/L) 15N-TCNM percentage in total TCNM

15N-DCAN percentage in total DCAN

NH2Cl Org-N

Tyrosine 6 0.2 96.8 89.5Asparagine 6 0.2 97.0 92.4

Aspartic acid 6 0.2 22.8 71.7

Glycine 15 0.5 7.7 0

Glycylglycine 15 0.5 62.8 0

Pyrrole 15 0.5 92.9 31.2Methylpyrrole 15 0.5 96.3 88.2

NH

pyrroleNH

methylpyrrole

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40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 3400

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

2000000

2200000

2400000

2600000

2800000

m/z-->

Abundance

Scan 1130 (13.730 min): ZD011.D\data.ms35.2 116.1

151.1

187.0

82.2 340.9269.0234.9 307.0210.9

40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 3400

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

2000000

2200000

2400000

2600000

2800000

m/z-->

Abundance

Scan 1130 (13.730 min): ZD010.D\data.ms35.2 117.1

152.1

188.0

85.1 342.9270.9237.0 305.0212.0

aspargine+14NH2Cl

aspargine+15NH2Cl

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tyrosineN14 #1207 RT: 21.94 AV: 1 SB: 12 21.76-21.94 NL: 1.44E5T: + c Full ms [ 40.00-500.00]

40 60 80 100 120 140 160 180 200m/z

0

10

20

30

40

50

60

70

80

90

100

Relative

Abunda

nce

133

78 132

10677

105104

44 1079051 76

tyrosineN15 #1207 RT: 21.94 AV: 1 SB: 5 21.79-21.86 NL: 1.74E5T: + c Full ms [ 40.00-500.00]

40 60 80 100 120 140 160 180 200m/z

0

10

20

30

40

50

60

70

80

90

100

Relativ

e Abun

dance

134

10678 133

10577

76 10790 104 13551 79

tyrosine+14NH2Cl

tyrosine+15NH2Cl

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CH2R CH

COO-

NH2 CH2R CH

COO-

N

H

Cl

CO2Cl-

CH2R CH NHH2O

NH3CH2R CH

O

NH2Cl

CH2R CH 15N Cl

215NH2Cl

215NH3

CH2R CH

COO-

NCl

15NH2Cl 15NH3

CO2Cl-

CH2R CH N Cl

CH2R CH N ClHCl

CH2R C N

Cl

Cl

CH C (DCAN)

HOCl NH2Cl H2O

N Cl

Cl OH

HCl

R CH CH N

Cl

OH

HOClR CH CH N

Cl

OH

HOCl

H2O

ClOH

R CH C N

OH

Cl

Cl

Cl OHRCHO

ClN

OH

C

Cl

Cl

HNO2C

Cl

Cl

Cl

(TCNM)

CH2R CH

Cl

H2O

N

Yang X., Shen Q.Q et al (2012) Chemosphere, 88, 25-32.

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Dichloroacetonitrile (DCAN)

Without preozonation

With preozonation

Yang X et al (2012) Environmental Science & Technology, 46, 12832.

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15N-DCAN vs. DOC/DON

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Trichloronitromethane (TCNM)

Without preozonationWith preozonation

Yang X et al (2012) Environmental Science & Technology, 46, 12832.

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DBP Control Techniques

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COAGULATION

SEPARATION

FILTRATION

2

1 3

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Common Ozone Byproducts

O

CHH

O

CHH3C

Mono-aldehydes

CC

H

O O

H

CC

H3C

O O

HDi-aldehydes

CC

H3C

O O

OHCC

H

O O

OH

Keto-acidsor

Aldo-acids

67Yang et al., 2012, Journal of Hazardous Materials, 239-240, 348-354.

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Ozone dose

Ozone preoxidation

O3 preoxidation generally enhanced TCNM formation during subsequent chlorination.

MuCurry... Environ. Sci. Technol., 2016, 50, 1209.

Primary and secondary amines were the dominant TCNM precursors.

TCNM

n Safe drinking water is a basic need, and its provision has been a top-priority issue worldwide.

n The main challenge to the drinking water industry is to deliver a product that is microbiologically and chemically safe as well as aesthetically pleasing.

Liu... Environ. Sci. Technol., 2016, 50, 8945.

Conclusions

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Chlorine; Chloramine; Chlorine dioxide; UV; Ozone

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For your references

n http://www.worldwater.org/n http://www.who.int/water_sanitation_health/n http://www.epa.gov/safewater/

Email: [email protected]

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Disinfection and disinfection byproducts...USEPA Stage 1 D/DBP Rule USEPA Stage 2 D/DBP Rule WHO...

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