Trihalomethanes formation Trihalomethanes formation after chlorination processafter chlorination process

Kovacs Melinda Haydee1, Dumitru Ristoiu1, Iovanca Haiduc1, Sidonia Vancea2Kovacs Melinda Haydee1, Dumitru Ristoiu1, Iovanca Haiduc1, Sidonia Vancea21Babes Bolyai University of Cluj-Napoca, Faculty of Environmental Science, Str. P-ta Stefan cel Mare, 1Babes Bolyai University of Cluj-Napoca, Faculty of Environmental Science, Str. P-ta Stefan cel Mare,

no.4, 400084, Cluj-Napoca, email: haydee_kovacs@yahoo.comno.4, 400084, Cluj-Napoca, email: haydee_kovacs@yahoo.com 2Garda de mediu, Comisariatul judetean Cluj, str. G-ral T. Mosoiu, nr. 49, Cluj-Napoca, Romania.2Garda de mediu, Comisariatul judetean Cluj, str. G-ral T. Mosoiu, nr. 49, Cluj-Napoca, Romania.

ChlorinationChlorination• Chlorine and its

compounds are the most commonly used disinfectants for water treatment in Romania.

Advantages Disadvantages

Provides a strong residual in the distribution system

Formation of disinfection by-products (DBPs) especially trihalomethanes (THMs)

Easily applied, controlled, and monitored

Provides poor Cryptosporidium* and Giardia ** control

Relatively inexpensive

Effective at low concentration

Highly effective against most pathogens

* Cryptosporidium parasite is the cause of gastrointestinal diseases (USEPA, 1997)** Giardia Lamblia is the cause of gastrointestinal illness (e.g. diarrhea, vomiting, cramps) (USEPA, 1997)

Tabel 1: Advantages and disadvantages of chlorine

(Rook, 1976; El-Shafy and Grunwald, 2000; Clark, 1998)

What happened with chlorine in water ?What happened with chlorine in water ?

Chlorine dissolved in water:Chlorine dissolved in water:

ClCl2 2 + H + H22OO HOCl + H HOCl + H ++ + Cl + Cl --

HOCl generally reacts with the various components thatmake up chlorine demand as follows:

HOCl + Cl HOCl + Cl demanddemand productsproducts

Reaction of chlorine in water

Oxidation of bromide: DBPs

Reaction with NOM: DBPs

TrihalomethanesTrihalomethanesTHMs ?THMs ?

Trihalomethanes (THMs)(THMs) are organohalogen compounds.

They are formedare formed after reaction of chlorine with natural organic matter (NOM) present in all water.

Natural organic matter in water Natural organic matter in water (Precursors)(Precursors)

Chlorinated organic intermediatesChlorinated organic intermediates

Complex Complex reaction reaction pathwaypathway

+ HOCl+ HOCl

THMsTHMs

HOClHOCl

Fig. 1: THMs formation pathway

• Cl2 + H2O → + H+ + Cl-• HOCl + Br- → + Cl-• HOCl + I- → + Cl2

HOCl

HOBr

HOI

HOX

THMs include:THMs include: - Chloroform - Chloroform

(CHCl(CHCl33))

- Dibromochloromethane- Dibromochloromethane

(CHBr(CHBr22Cl)Cl)

- Bromodichloromethane- Bromodichloromethane

(CHBrCl(CHBrCl22))

- Bromoform- Bromoform

(CHBr(CHBr33))

Possible Health effects of THMs

WHY THMs ?WHY THMs ? THMs appear to be the most prevalent halogenated by-THMs appear to be the most prevalent halogenated by-

products of chlorination.products of chlorination.

DBPsDBPs CompoundCompound Rating*Rating* Possible detrimental Possible detrimental effectseffects

THMs

CHCl3 B2 Cancer, liver, kidney, and reproductive effects

CHCl2Br C Nervous system, liver, kidney and reproductive effects

CHClBr2 B2 Cancer, liver, kidney and reproductive effects

CHBr3 B2 Cancer, nervous system, liver and kidney effects

Toxicological information for THMs (modified after USEPA, 1999b)Toxicological information for THMs (modified after USEPA, 1999b)

B2 - Probable human carcinogen (sufficient laboratory evidence)

C - Possible human carcinogen

Compound WHO

(1993)

USEPA

(2001)

Canada

(2001)

Aus-NZ

(2000)

UK

(2000)

Romania

Total THMs 0.100

g/l

0.080

g/l

0.100

g/l

0.250

g/l

0.100

g/l

0.100

g/l

Standards / Guidelines related to THMs (mg/l) in various jurisdictions of the World

Tabel 2: Standards/Guidelines related to THMs (mg/l) in different countries of the world.

* Maximum Contaminant Level Goals (MCLG)

Location of the sampling points

• Location of the sampling points WTP Gilau

• Experiments were carried out with five town from judetul Cluj: Cluj-Napoca, Dej, Beclean, Jibou and Gherla

THMs monitoring by GC• THMs were analyzed using headspace technique gas chromatography with an electron capture

detector.

• The GC was fitted with a 30 m TR-5V capillary column - Cyanopropylphenyl Polysiloxane, the internal diameter was 53 mm and the film thickness was 3 m (Thermo Finningan, USA)

Fig.: Static headspace technique

Fig.: Laboratory instrument – GC - ECD

Fig.: THM chromatograms obtained after water analysis

Relativ standard deviation for 20 µg/l and 80 µg/l is between 1.9-3.2 %Recovery for 1 µg/l, 20 µg/l and 80 µg/l µg/l are in range 93 – 120 %Limit of detectuion for THMs is: CHCl3 is 0.3 µg/l ; CHCl2Br is 0.2 µg/l; CHClBr2 is 0.3 µg/l; CHBr3 is 0.6 µg/l

Table: CHCl3 g/l measured in Water Treatment Plant and distribution system

CHClCHCl33 concentration measured in WTP Gilau in 2006 concentration measured in WTP Gilau in 2006

Sampling place August September October November December

Raw water u.l.d u.l.d u.l.d 1.02 u.l.d

Filtrated water u.l.d. u.l.d. u.l.d. u.l.d u.l.d.

Exit reservoir 14.28 8.4 30.3 4.01 2.22

Sapca Verde 46.83 47.4 51.6 13.43 9.34

Beer factory 55.08 47 55.8 7.98 6.36

Faculty of Chemistry 66.8 66.9 72.8 13.58 27.77

Faculty of Environmental Science 60.3 66.4 65.8 27.26 21.08

Institute of public health 68.4 71.1 41.4 16.54 28.17

Month 2007Month 2007

Sampling place January February March April May June July August

Raw water u.l.d u.l.d u.l.d u.l.d u.l.d u.l.d u.l.d u.l.d

Filtrated water u.l.d. u.l.d. u.l.d. u.l.d. u.l.d. u.l.d. u.l.d. u.l.d.

Exit reservoir 25.44 12.08 8.09 8.22 14.75 19.26 31.05 28.02

Sapca Verde 27.06 28.36 16.71 20.81 36.11 58.44 63.08 64.31

Beer factory 32.15 31.62 18.7 29.26 40.69 60.28 65.24 69

Fac.of Chemistry 38.51 48.6 18.99 27.12 43.05 65.31 67.29 78

Fac. of Environ. 35.9 36.73 20.9 32.41 54 64.28 71.33 76.25

Inst. publ health 40.49 48.6 21.6 33.66 50.23 66.35 69.02 81.14

ZALAUZALAU

g/lg/l CHCl3 CHCl2Br CHClBr2 CHBr3

Raw WaterRaw Water u.l.d. u.l.d. u.l.d. u.l.d.

Filtrated W.Filtrated W. 6.34 u.l.d. u.l.d. u.l.d.

Distrib. Syst.Distrib. Syst. 161.51 43.78 4.63 u.l.d.

ORADEAORADEA

g/lg/l CHCl3 CHCl2Br CHClBr2 CHBr3

Cl. Nestab 36.5 14.23 3.81 s.l.d.

Cl. Nestab 19.2 9.06 2.63 s.l.d.

Mal. dr 14.7 9.95 3.54 s.l.d.

Mal. stg 1.58 s.l.d. s.l.d. s.l.d.

TIMISOARA

g/lg/l CHCl3 CHCl2Br CHClBr2 CHBr3

Sampl.1. 99.16 31.93 3.99 s.l.d.

Sampl.2. 90.31 27.11 2.95 s.l.d.

Sampl.3. 0.33 13.94 76.51 182.70

Sampl.4. 24.68 56.10 75.45 93.12

IASIIASI

g/lg/l CHCl3 CHCl2Br CHClBr2 CHBr3

Sampl.1. 12.51 2.33 s.l.d. 3.11

Sampl.2. 115.08 91.45 53.39 6.78

Sampl.3. 100.73 84.08 50.29 6.92

Sampl.4. 17.33 18.50 12.46 2.16

BISTRITA

g/lg/l CHCl3 CHCl2Br CHClBr2 CHBr3

Sampl.1. 181.79 7.142 s.l.d. s.l.d.

Sampl.2. 95.18 2.46 s.l.d. s.l.d.

Sampl.3. 104.99 5.00 s.l.d. s.l.d.

Sampl.4. 9.35 1.75 s.l.d. s.l.d.

Sampl.5. 140.63 5.708 s.l.d. s.l.d.

DEJDEJ

g/lg/l CHCl3 CHCl2Br CHClBr2 CHBr3

Sampl.1. 44.29 11.50 1.02 s.l.d.

Factors affecting THM formation

MONTHMONTH Chlorine dose Chlorine dose

2006 (mg/l)2006 (mg/l)

Chlorine doseChlorine dose

2007 (mg/l)2007 (mg/l)

JanuaryJanuary 1.11.1

FebruaryFebruary 1.01.0

MarchMarch 11 1.11.1

AprilApril 11 1.21.2

MayMay 1.21.2 1.41.4

JuneJune 11 1.41.4

JulieJulie 1.41.4 1.51.5

AugustAugust 1.61.6 1.71.7

SeptemberSeptember 1.61.6

OctoberOctober 1.41.4

NovemberNovember 1.31.3

DecemberDecember 1.11.1

There are several factors affecting the formation potential of THMs. The major variables that affect THM formation are: Chlorine dose and residual; Concentration and nature of NOM (mainly humic substances); Contact time; pH; Water temperature; Presence of inorganic ions like bromide; Type of raw water also affects the THM levels.

Higher THMs concentrations are expected at higher levels of the above mentioned parameters.Higher THMs concentrations are expected at higher levels of the above mentioned parameters. The effect of disinfectant concentration on THM formation have shown as the disinfectant concentration The effect of disinfectant concentration on THM formation have shown as the disinfectant concentration increases also THM formation increase. increases also THM formation increase.

y = 70.547x - 46.887

R2 = 0.5057

0

10

20

30

40

50

60

70

80

90

0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8

Chlorine dose (mg/l)

CH

Cl3

(u

g/l

)

Fig.: With increases of chlorine dose it is observed also the CHCl3 increases.

CHCl3 value in Exit Reservoire sampling point

0

5

10

15

20

25

30

35

Month

CH

Cl3

(u

g/l)

CHCl3 value in Chemistry Faculty sampling point

0

10

20

30

40

50

60

70

80

90

Month

CH

Cl3

THMs measurements in Water Treatment Plant and THMs measurements in Water Treatment Plant and distribution system in Cluj-Romania distribution system in Cluj-Romania

in different monthin different month

05

1015

Mar

ch

Apr

il

May

June

July

Aug

ust

Sep

tem

ber

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Feb

ruar

y

Mar

ch

Apr

il

May

June

July

Aug

ust

2007 2006

Fig.: With increases of filtrated water temperature it is observed also the CHCl3 increases.

General presentation of chloroform evolution in the WTP Gilau and distribution system (2006-2007)

20062006

20072007

540

630

augu

st

sept

embr

ie

octo

mbr

ie

noie

mbr

ie

dece

mbr

ie

ianu

arie

febr

uarie

mar

tie

april

ie

mai

iuni

e

iulie

augu

st

0

10

20

30

40

50

60

70

80

90

CH

Cl3

(u

g/l

)

Time (min) Month

CHCl3 in distribution system

august

septembrie

octombrie

noiembrie

decembrie

ianuarie

februarie

martie

aprilie

mai

iunie

iulie

august

Chlorine and THM kineticsChlorine and THM kinetics• The experiments were conducted under two conditions: Base line conditionsBase line conditions

(pH 7, 21 C°, 2.5 mg/l Cl2) to gain information about the change of the organic matter in the raw water and Seasonally variable conditionsSeasonally variable conditions to simulate the actual process at the treatment plant.

• Experiments under seasonally variable conditions were carried out with pH and temperature and chlorine dose as measured in the pretreated water on the sampling day.

Chlorine kinetics july 2007 - seasonally variable condition

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

1.800

0 50 100 150 200 250 300 350 400 450

Time (minutes)

mg

/l

Total chlorine

Free chlorine

Monochloramin

THM kinetics july 2007 - seasonally variable condition

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

0 50 100 150 200 250 300 350 400 450

Time (minutes)

CH

Cl3

(u

g/l)

CHCl3

CHClCHCl3 3 concentrationconcentration measured in sampling point from WTP Gilau and CHClmeasured in sampling point from WTP Gilau and CHCl33

concentration obtained in laboratory experiment in different month in 2006concentration obtained in laboratory experiment in different month in 2006

S.P.S.P. August September October November December

MM EE MM EE MM EE MM EE MM EE

33 14.28 10.25 8.4 13.5 30.3 12.84 4.01 4.98 2.22 4.98

44 46.83 48.55 47.7 48.92 51.6 50.15 13.43 20.75 9.34 25.09

55 55.08 57.11 47 48.92 55.8 55.09 7.98 24.04 6.36 27.90

66 66.8 61.42 66.9 65.91 72.8 55.11 13.58 27.01 27.77 28.89

77 66.03 62.99 66.6 69.10 65.8 56.99 27.26 27.60 21.08 29.41

88 68.4 63.16 71.1 69.86 41.4 57.15 16.54 28.16 28.17 29.43

CHClCHCl3 3 concentrationconcentration measured in sampling point from WTP Gilau and CHClmeasured in sampling point from WTP Gilau and CHCl33

concentration obtained in laboratory experiment in different month in 2007concentration obtained in laboratory experiment in different month in 2007

S.P.S.P. JanuaryJanuary FebruaryFebruary MarchMarch AprilApril

MM EE MM EE MM EE MM EE

33 25.44 15.76 12.08 19.00 8.09 9.95 8.22 9.16

44 27.06 31.56 28.36 37.60 16.71 17.82 20.81 28.46

55 31.15 34.87 31.62 40.56 18.70 19.44 29.26 31.56

66 38.51 37.53 48.6 44.12 18.99 21.03 27.12 33.01

77 35.9 38.43 36.73 46.00 20.90 21.78 32.41 33.99

88 40.49 38.76 48.6 46.67 21.60 22.04 33.86 34.05

CHClCHCl3 3 concentrationconcentration measured in sampling point from WTP Gilau and CHClmeasured in sampling point from WTP Gilau and CHCl33

concentration obtained in laboratory experiment in different month in 2007concentration obtained in laboratory experiment in different month in 2007

S.P.S.P. MayMay JuneJune JulyJuly AugustAugust

MM EE MM EE MM EE MM EE

33 14.75 18.45 19.26 21.03 31.05 20.90 28.02 29.04

44 36.11 39.46 58.44 52.03 63.08 59.64 64.31 59.39

55 40.69 44.33 60.28 59.65 65.24 64.90 69.00 67.33

66 43.05 49.02 65.31 63.10 67.29 69.89 78.00 71.02

77 54.00 50.36 64.28 63.94 71.33 70.97 76.25 72.05

88 50.23 50.36 66.35 64.25 69.02 71.54 81.14 72.93

• Relationship between chlorine consumption and CHCl3 formation under seasonally variable condition. NH2Cl concentration were subtracted from the chlorine consumption.

0.000

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Chlorine consumption (mg/l*min) - 2007

CH

Cl3

(u

g/l

) -

20

07 january

february

may

june

july

august

y = 55.03x - 0.7209R2 = 0.9072

We found a good corelation between the residence time We found a good corelation between the residence time and THM and chloroform consumption – r2 was 0.9072and THM and chloroform consumption – r2 was 0.9072The first order rate constant was determine – 0.024 - 0.066 M-1s-1The first order rate constant was determine – 0.024 - 0.066 M-1s-1

CONCLUSIONS

• Static headspace sample preparation can be used for quantitative analysis of THMs in environmental samples.

• Chloroform was the dominant THM species observed after the chlorination.

• THM concentration depended on the applied initial chlorine demand of the water samples, as the chlorine dose was increased, more THM formed.

• For a given initial chlorine dose, the formation of THMs and consumption of chlorine were both completed at the same reaction time, however, the time, period required for the completion of THM formation varied with the chlorine dose and season. At high chlorine dose, THM formation was complete earlier then the low doses due to the fact that the initial chlorine concentration is an important factor affecting the time of completion of the reaction as well as the amount and rate of THM formation (higher values of initial chlorine results in higher reaction rates).

• The THM formation rates in the distribution system of Cluj-Napoca have a high seasonal variability.

• The main parameters causing variances in the THM formation rate were the concentration and composition of the organic substances in the raw water.

• Residual chlorine concentration during the completion of THM formation, the overall yield values (total THM formed/total chlorine consumed during the entire reaction periods) as well as the average yield values (g TTHM formed/mg Chlorine consumed between two reaction times) differ through sampled months that may be attributed to the variations in the nature of organic matter.

• In all months, the formation yields were highest during the first hours of reaction time.

Thank You !!!!!!!!!!