Water Arabia 2011 Conference and Exhibit.Gulf Hotel-Manama, Kingdom of Bahrain

January 31, February 1 & 2, 2011.

Chlorine dioxide as a successful antifoulant treatment in large cooling system-Case history

Giuseppe Petrucci

ISIA INTERNATIONAL FZCO DUBAI-UAEClO2 technologies and service“UNDERWATER TECH.”

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ISIA INTERNATIONALactivities in

water disinfection

ClO2 UNDERWATER TECHChlorine dioxidetechnology

POTABLE WATER

Seawater antifouling Treatment

OILFIELDBIOCIDETREATMENT

WASTE WATER

FOOD ANDBEVERAGEINDUSTRY

PAPER MILLS

DESALINATION PROCESS

SEAWATER ANTIFOULING TREATMENT

•Power plant•Petrochemical plant•Refinery•Steel mills•Fertilizer plant•Thermal and R.O. desalination plant make up

ISIA SISTEMIISIA SISTEMIactivities in activities in water water disinfectiondisinfection

ClO2 UNDERWATERChlorine dioxidetechnology

POTABLE WATER

SEAWATERANTIFOULINGTREATMENT

OILFIELDBIOCIDETREATMENT

WASTE WATER

FOOD ANDBEVERAGEINDUSTRY

PAPER MILLS

DESALINATION PROCESS

CHLORINE DIOXIDE CHARACTERISTICS

4 5 6 7 8 9 10 11

01 02030405060708090

100

bio

cida

l act

ivity

%

p H

chlorine dioxide

chlorine

CHARACTERISTICS SUITABLE FOR:

u sea water once-throughcooling system (pH 8.5)

u recirculating coolingwater system (pH > 8)

u fertiliser & ammonia plantcooling system

u waste water

u refinery and petrochemicalcooling system

u seawater desalination plant

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The biocidal activityis constant over thepH 6 - 9

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NN

HHHH

No reaction withammonia and urea

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OrganicOrganicNo reaction withorganic matterand oil

CHARACTERISTICS SUITABLE FOR:

u potable waterworksu food and beverage industryu waste water treat. plants

u minimize corrosion

u minimize corrosionu minimize bad smell

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TTHMs TTHMs pecursorspecursors No formation of

halogenatedcompounds(TTHMs-dangerousfor human health)

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sulfate sulfate reducing reducing bacteriabacteria Strong biocidal

activity againstanaerobic bacteria

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SS

FeFe

Oxidation ofsulfide to sulfate(sulfide scavenger)

CHLORINE DIOXIDE CHARACTERISTICS

CHLORINE DIOXIDE

Chlorine Dioxide is very active against:

ClO2 + e- ---> ClO2- (Eo = 0,95 V)

ClO2 + 4 H+ + 5 e- ---> Cl- + 2 H2O (Eo = 1,51 V)

-- bacteriabacteria-- virusesviruses-- algae algae -- fungifungi--macroorganismmacroorganism

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6 6,5 7 7,5 8 8,5 9 9,5 10

0

10

20

30

40

50

60

70

80

90

100

chlo

rine

spec

ies

in s

olut

ion

%

pH

2ClHOCl

OCl-

CHLORINE SPECIES FORMATION IN WATER ACCORDING TO pH

ClO2-

ClO2-

NOgrowing

Bacteria colony

NEWGROWING

STILL ALIVE

STILL ALIVE

STILL ALIVE

Cl-

ClO2-

Bacteria wall

--

--

-

-

---

-

x

CHEMICAL FEATURES OF CHLORINE DIOXIDE (ClO2)

u it is a gas and must be generated on site

u it is soluble in water

u it does not undergo hydrolysis at pH of cooling water

u it is a strong oxidising agent

MICROFOULINGMICROFOULING

MACROFOULINGMACROFOULING

• Bacteria, Algae, Fungi, • Microbial corrosion• Loss of the heat exchange (loss in

the efficiency of the thermal cycle)

•• Mussels, Barnacles, Serpulid worms, Hidroys

• Encrusting, loss of water flow, tubes plugging corrosion under deposit.

The Biofouling problem

ClO2 and Cl2 effectiveness in seawater at pH 8,2

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10

20

30

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60

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100

0 30 60 90 120 150 180 210 240 270 300

Contact time second

Org

anis

m s

urvi

val %

Cl2 1,0 mg/l

ClO2 0,3 mg/l

Cl2 3,0 mg/l

ClO2 1 mg/l

- Cl2 demand = 1,7 mg/l- ClO2 demand = 0,9 mg/l

Chlorine dioxide and chlorine comparison against bacteria

apr-99

mag-99

giu-99

lug-99

ago-99

set-99

ott-99

nov-99

dic-99

gen-00

feb-00

mar-00

0

10

20

30

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60

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80

ClO2Cl2blank

Kg/m2*y

Dosage mg/l

Summer- Cl2 2.0- ClO2 0.4

Winter- Cl2 1.3- ClO2 0.2

CHLORINE DIOXIDE AND CHLORINE COMPARISON ON MACROFOULING GROWTH

20 2 1 0,5

0

100

200

300

400

500

600

700

800

CHLORINE

15°C25°C

35°C

25°C

CHLORINEDIOXIDE

15°C

35°C

dosage rate mg/l

total THM ppb

contact time 60 minute

contact time 20 minute

CHLORINE DIOXIDE AND CHLORINE COMPARISON ON THM FORMATION IN SEAWATER HAVING

A TOC OF 5 MG/L

contact time 10 minute

From “ environmental impact of biocidal anti fouling al ternative treatments of seawater once through cooling systems ”R. Ambrogi ENEL

CHLORINE DIOXIDE ADVANTAGES

u very performant in short time contact system

u reduced corrosion (compared with chlorine)

u very performant at high pH (sea water, all organic and Zn/phosphonate treat.)

u very performant in ammonia contaminated system (fertilizer and ammonia plant)

u It can be applied by a simply chlorine plant modification or possibility no chlorine treatment

u environment friendly disinfection treatment

CHLORINE DIOXIDE GENERATIONClO2 can be generated on site by using water solutions of:

Sodium Chlorite,Hypochlorite and acid according to the following reaction:

2NaClO2 + NaClO + 2HCl 2ClO2 + 3NaCl + H2O

Or by using

Sodium Chlorite and Chlorine

according to the following reaction:

2 NaClO2 + Cl2 --> 2 ClO2+ 2 NaCl

Or by using

Sodium Chlorite and Hydrochloric Acid

according to the following reaction:

5 NaClO2 + 4 HCl --> 4 ClO2+ 5 NaCl + 2 H2O

pH

pH

NaClO fromelectrochlorinator

Chlorine dioxideto dosage point

HCl 33% Sodium chlorite

Chlorine dioxideto dosage point

Sodium chlorite

Chlorinated water

ClO2 “hypochlorite” generating system Conversion of hypochlorite from electrochlorinator into Chlorine Dioxide

HClNaClO2

Dilution H2O

Water to be disinfected

Water to be disinfected

H2O

H2O

ClO2Water solution

ClO2 “under water” generating system Reaction chamber located into the dilution water line

ClO2

ClO2

ISIA SISTEMI

Chlorine dioxide reagents storage tanks

Chlorine dioxide reagents pumping station and control monitoring system

Chlorine dioxide “underwater reaction chambers”

Reaction chambers located inside the racket pipe

water basin after 18 month operation.

Description of the Facility and Cooling Water(PLANT 1)

PLANT: LARGE PETROCHEMICAL

FEEDING: SEAWATER FROM THE INTAKE

SYSTEM: BASIN, SCREEN FILTERS, PUMPING STATION BASINS, COOLING TOWERS BASIN, HEAT EXCHANGERS, RETURN TO THE TOWERS,BLOW DOWN TO THE SEA.

FLOWRATE: RR. 175,000 m3/h (full capacity)

CHLORINE DIOXIDE DOSAGE: from March to October 2 shot/day at 0.5 ppm as long as 1.5 hour each shot (TOTAL 3 H/DAY). Winter 2 shot/day at 0.5 ppm as long as 1 hour each shot(TOTAL 2 H/DAY).

DOSAGE START UP: February 2009.

Description of the Facility and Cooling Water (PLANT 2)

PLANT: LARGE PETROCHEMICAL

FEEDING: SEAWATER FROM THE INTAKE

SYSTEM: SCREEN FILTERS, PUMPING STATION, PUMPING STATION, HEAT EXCHANGERS, RETURN TO THE TO THE SEA.

FLOWRATE: 32,000 m3/h (full capacity)

CHLORINE DIOXIDE DOSAGE: 2 shot/day at 0.3 ppm as long as 1 hour each shot (TOTAL 2 H/DAY).

DOSAGE START UP: February 2009.

Why chlorine dioxide?

Chlorine dioxide was selected, to treat the 2 plants instead of chlorination for safety, environmental and performance reasons.

In fact, chlorine and sodium hypochlorite are responsible of bromate and bromoform formation in seawater which are considered very toxic for aquatic life of the Arabian Gulf.

Chlorine dioxide demonstrated to be very efficient at very low dosage rate, minimizing its residual and the formation of brominated compounds at the discharge point.

EasyaReadox SYSTEM

electrochemical biofilm sensor.

EasyaReadox SYSTEM

electrochemical biofilm sensor.

As chlorine dioxide shots increase, the baseline come back to its original value showing no biofilm activity

Constant baseline value indicates that no biofilm activity takes place and the whole system is clean.

Conclusions

We underline the following advantages:

•Chlorine dioxide has allowed to minimize the growing of both micro and macro-fouling inside cooling systems of petrochemical plants at very low dosage rate,

•Monitoring system has demonstrated to be the “Brain” of the treatment programme. It has permitted to inject chlorine dioxide in a proper quantity and in the right moment, saving material and protecting the environment.

أشكركم على حسن ضیافتكم واھتمامكم Thank you very much for your hospitality and your

kind attention

ISIA INTERNATIONAL FZCO Dubai Airport Free Zone Authority

Office 238- 6WB P.O.Box 293896-DUBAI-UAE

Tel. +971.(0)47017959Fax. +971(0)47017962

e.mail: gpetrucci@isiainternational.com

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