Chlorine
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Ngày 23/10/2018 |
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Chia sẻ tài liệu: chlorine thuộc Bài giảng khác
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CHLORINATION
IN AQUARIA
MÓNICA VALLS, NÚRIA GIL, PABLO AREITIO
Parques Reunidos Valencia, S.A. L’Oceanogràfic.
Junta de Murs i Valls, s/n
46013 Valencia, Spain.
[email protected]
1. INTRODUCTION
CHLORINATION AS WATER TREATMENT
The most widely-used technique of water disinfection in aquatic facilities.
First modern application:
Disinfection in hospitals (1846)
2. CHLORINE AND ITS FORMS
2.1. THE CHLORINE
“Chloros”: Greek translation of green
Atomic symbol: Cl2
Halogen family
Abundant element in nature (NaCl)
Strong oxidant: Disinfection applications
2. DEFINITION OF CHLORINE & CHLORINATION
2.2. COMMONLY USED FORMS OF CHLORINE
3. CHLORINATION & ITS CHEMISTRY
3.1. CONCEPT
CHLORINATION: CHLORINE + WATER
The most important reaction in the chlorination process is the formation of hypochlorous acid (HOCl), which is the most powerful disinfecting form
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
A. EX SITU:
Disinfecting chlorine form not produced on-site
B. IN SITU:
Disinfecting chlorine form produced on-site (electrolysis)
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
A. Ex situ:
iChlorine gas
iCalcium hypochlorite
iSodium hypochlorite
iChlorine dioxide
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
A. Ex situ:
a - WITH INTERMEDIATION OF HYPOCHLOROUS ACID:
iCl2 + H 2O g HOCl + (H+ + Cl- ) n OCl- + H+
iCa (OCl) 2 + 2H2O g 2HOCl + Ca + OH
iNaOCl + H2O n HOCl + NaOH n H+ + OCl- + (OH- + Na+ )
b - WITHOUT INTERMEDIATION OF HYPOCHLOROUS ACID: Chlorine dioxide
i 2NaOCl2 + Cl 2 g 2ClO 2 + 2NaCl
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
B. In situ:
Principle: Electrolysis
2NaCl + 3H2O g NaOCl + HOCl + NaOH + 2H2
Generators
-Electrolytic battery using titanium anodes
-Dependent on electricity & water quality
Ideal Membrane cell (White, G.C. 1992 Handbook of chlorination)
3. CHLORINATION & ITS CHEMISTRY
3.3. FACTORS AFFECTING CHLORINATION
1.- Form : Chlorine dioxide > salt efficiency
2.- Temperature:
hTºC, hefficiency
iTºC, hstability
3.- Time of contact: htime, hefficiency
4.- Presence of organic substances: iefficiency
5.- pH: HOCl n OCl- + H+ / ipH, hefficiency
pH: Cl2 + H20 n HClO + H+ + Cl- n H+ + ClO-
3. CHLORINATION & ITS CHEMISTRY
3.3. FACTORS AFFECTING CHLORINATION
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
ORGANIC MATTER OXIDATION
4.2. NEGATIVE EFFECTS
SHORT TERM EFFECTS
LONG TERM EFFECTS
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
Sterility of water: Neither feasible nor desirable
Control: (Thermotolerant) Coliforms (44.5ºC):
E. coli, Klebsiella sp., others.
Maximum acceptable concentracion of coliforms:
< 1000 CFU / 100 ml
Free Chlorine concentrations for MM tanks:
0,5 – 1,0 ppm (Depending on species, LSS, DOC, others)
Free Chlorine concentrations for Fish tanks:
<0,03 (UNCOMMON)
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
Chlorine disinfection mechanism:
Bacterium cell (White, G.C. 1992 Handbook of chlorination)
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
Comparison of available disinfectant forms of chlorine
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
ORGANIC MATTER OXIDATION
Superchlorination: Breakpoint procedure
Use of a high concentration of chlorine (combined residual x10) to oxidize unwanted nitrogenous pollution (ammonia and chloramines) from water.
Breakpoint description
4. BIOLOGICAL EFFECTS
4.2. NEGATIVE EFFECTS
SHORT TERM EFFECTS
Oxidation of living tissues necrosis >> cell death
Highly irritant to eyes and respiratory system (chloramines in MM)
Chlorine poisoning causing hypoxia in fish
4. BIOLOGICAL EFFECTS
4.2. NEGATIVE EFFECTS
LONG TERM EFFECTS
A. CARCINOGENIC BYPRODUCTS:
Chloro-organic byproducts called trihalomethanes (THMs) like chloroform, bromoform, bromodichloromethane and hundreds of toxic DBPs are suspected carcinogens and not yet well understood
B. ENVIRONMENTAL IMPACT
Unknown accumulation in marine biota
5. MEASUREMENT
5.1. Need of control:
Disinfection efficiency
Toxicity control
5.2. Factors affecting the choice of technique:
Range requirements
Accuracy of technique
Chemical forms of chlorine
On-site analysis or lab analysis
5. MEASUREMENT
5.3. Analytical methods
A. Colorimetric Methods
N,N - diethyl - phenylenediamine method (DPD)
Photometry
Orthotolidine
Leucocrystal violet method
FACTS (Syringaldaxine)
Others: Chlorophenol Red CPR, Amaranth, Lissamine Green B
B. Titrimetric Methods and others
Amperometric titration
Spectrophotometry
Ion Chromatography (ClO2-,ClO3-)
DPD Ferrous titrimetric method
Iodometric titration and FIA
5.3. Analytical methods
N,N – diethyl - phenylenediamine method (DPD)
Standard method * wide range * rapid *cheap * does not
require a high level of expertise.
Photometry: Accurancy > DPD but
similar characteristics
Amperometric titration:
Expensive * Accurate.
Spectrophotometry: Expensive *
Difficult calibration
5. MEASUREMENT
6. CHLORINE REMOVAL
6.1. Importance
Prevention of toxicity of chlorine (overdosing)
Reduction of toxicity of DBPs
6.2. Techniques
Dilution
Evaporative techniques
Reduction (Sodium thiosulphate and others)
Adsorption
UV radiation
7. ADVANTAGES AND DRAWBACKS OF CHLORINATION
7.1. ADVANTAGES
Well-known technology
Broad germicidal spectrum
Residual persistence (residual disinfection)
Biocompatibility (at certain dosages)
Easy and flexible application
Inexpensive
7. ADVANTAGES AND DRAWBACKS OF CHLORINATION
7.2. DISADVANTAGES
Other procedures needed prior to chlorination
Toxicity of byproducts
Limited disinfection efficiency (viruses, cysts)
Adverse environmental impact
Safety and security regulations (transport, storage, and handling)
8. CONCLUSIONS
Chlorination is a well known, effective and versatile
technology for disinfection to be improved in conjunction with ozone and other water treatments in order to achieve safer and more comfortable environments for the aquatic species kept in Aquaria.
9.- BIBLIOGRAPHY
Connell,G.F The chlorination/Chloramination handbook. AWWA,Denver,CO(1996).
Disinfectants and disinfectant By-Products. Proposed Rule.Fed.Reg(July 29,1994)
Fenner,bob.1999. Frequent Partial water changes.FAMA 5/99
Ibañez, Jorge G.; et.al. Microscale environmental chemistry: production of chlorine dioxide.
White, G.C. 1992 Handbook of chlorination, 4 rd.ed.
10.- ACKNOWLEDGMENTS
Akira Kanezaki, for translating this powerpoint presentation even though he doesn’t speak a lick of Spanish.
Allright… some other people at L’Oceanogràfic may have given us a little bit of help, too.
IN AQUARIA
MÓNICA VALLS, NÚRIA GIL, PABLO AREITIO
Parques Reunidos Valencia, S.A. L’Oceanogràfic.
Junta de Murs i Valls, s/n
46013 Valencia, Spain.
[email protected]
1. INTRODUCTION
CHLORINATION AS WATER TREATMENT
The most widely-used technique of water disinfection in aquatic facilities.
First modern application:
Disinfection in hospitals (1846)
2. CHLORINE AND ITS FORMS
2.1. THE CHLORINE
“Chloros”: Greek translation of green
Atomic symbol: Cl2
Halogen family
Abundant element in nature (NaCl)
Strong oxidant: Disinfection applications
2. DEFINITION OF CHLORINE & CHLORINATION
2.2. COMMONLY USED FORMS OF CHLORINE
3. CHLORINATION & ITS CHEMISTRY
3.1. CONCEPT
CHLORINATION: CHLORINE + WATER
The most important reaction in the chlorination process is the formation of hypochlorous acid (HOCl), which is the most powerful disinfecting form
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
A. EX SITU:
Disinfecting chlorine form not produced on-site
B. IN SITU:
Disinfecting chlorine form produced on-site (electrolysis)
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
A. Ex situ:
iChlorine gas
iCalcium hypochlorite
iSodium hypochlorite
iChlorine dioxide
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
A. Ex situ:
a - WITH INTERMEDIATION OF HYPOCHLOROUS ACID:
iCl2 + H 2O g HOCl + (H+ + Cl- ) n OCl- + H+
iCa (OCl) 2 + 2H2O g 2HOCl + Ca + OH
iNaOCl + H2O n HOCl + NaOH n H+ + OCl- + (OH- + Na+ )
b - WITHOUT INTERMEDIATION OF HYPOCHLOROUS ACID: Chlorine dioxide
i 2NaOCl2 + Cl 2 g 2ClO 2 + 2NaCl
3. CHLORINATION & ITS CHEMISTRY
3.2. CHLORINE SUPPLY AND CHEMISTRY
B. In situ:
Principle: Electrolysis
2NaCl + 3H2O g NaOCl + HOCl + NaOH + 2H2
Generators
-Electrolytic battery using titanium anodes
-Dependent on electricity & water quality
Ideal Membrane cell (White, G.C. 1992 Handbook of chlorination)
3. CHLORINATION & ITS CHEMISTRY
3.3. FACTORS AFFECTING CHLORINATION
1.- Form : Chlorine dioxide > salt efficiency
2.- Temperature:
hTºC, hefficiency
iTºC, hstability
3.- Time of contact: htime, hefficiency
4.- Presence of organic substances: iefficiency
5.- pH: HOCl n OCl- + H+ / ipH, hefficiency
pH: Cl2 + H20 n HClO + H+ + Cl- n H+ + ClO-
3. CHLORINATION & ITS CHEMISTRY
3.3. FACTORS AFFECTING CHLORINATION
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
ORGANIC MATTER OXIDATION
4.2. NEGATIVE EFFECTS
SHORT TERM EFFECTS
LONG TERM EFFECTS
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
Sterility of water: Neither feasible nor desirable
Control: (Thermotolerant) Coliforms (44.5ºC):
E. coli, Klebsiella sp., others.
Maximum acceptable concentracion of coliforms:
< 1000 CFU / 100 ml
Free Chlorine concentrations for MM tanks:
0,5 – 1,0 ppm (Depending on species, LSS, DOC, others)
Free Chlorine concentrations for Fish tanks:
<0,03 (UNCOMMON)
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
Chlorine disinfection mechanism:
Bacterium cell (White, G.C. 1992 Handbook of chlorination)
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
DISINFECTION
Comparison of available disinfectant forms of chlorine
4. BIOLOGICAL EFFECTS
4.1. POSITIVE EFFECTS
ORGANIC MATTER OXIDATION
Superchlorination: Breakpoint procedure
Use of a high concentration of chlorine (combined residual x10) to oxidize unwanted nitrogenous pollution (ammonia and chloramines) from water.
Breakpoint description
4. BIOLOGICAL EFFECTS
4.2. NEGATIVE EFFECTS
SHORT TERM EFFECTS
Oxidation of living tissues necrosis >> cell death
Highly irritant to eyes and respiratory system (chloramines in MM)
Chlorine poisoning causing hypoxia in fish
4. BIOLOGICAL EFFECTS
4.2. NEGATIVE EFFECTS
LONG TERM EFFECTS
A. CARCINOGENIC BYPRODUCTS:
Chloro-organic byproducts called trihalomethanes (THMs) like chloroform, bromoform, bromodichloromethane and hundreds of toxic DBPs are suspected carcinogens and not yet well understood
B. ENVIRONMENTAL IMPACT
Unknown accumulation in marine biota
5. MEASUREMENT
5.1. Need of control:
Disinfection efficiency
Toxicity control
5.2. Factors affecting the choice of technique:
Range requirements
Accuracy of technique
Chemical forms of chlorine
On-site analysis or lab analysis
5. MEASUREMENT
5.3. Analytical methods
A. Colorimetric Methods
N,N - diethyl - phenylenediamine method (DPD)
Photometry
Orthotolidine
Leucocrystal violet method
FACTS (Syringaldaxine)
Others: Chlorophenol Red CPR, Amaranth, Lissamine Green B
B. Titrimetric Methods and others
Amperometric titration
Spectrophotometry
Ion Chromatography (ClO2-,ClO3-)
DPD Ferrous titrimetric method
Iodometric titration and FIA
5.3. Analytical methods
N,N – diethyl - phenylenediamine method (DPD)
Standard method * wide range * rapid *cheap * does not
require a high level of expertise.
Photometry: Accurancy > DPD but
similar characteristics
Amperometric titration:
Expensive * Accurate.
Spectrophotometry: Expensive *
Difficult calibration
5. MEASUREMENT
6. CHLORINE REMOVAL
6.1. Importance
Prevention of toxicity of chlorine (overdosing)
Reduction of toxicity of DBPs
6.2. Techniques
Dilution
Evaporative techniques
Reduction (Sodium thiosulphate and others)
Adsorption
UV radiation
7. ADVANTAGES AND DRAWBACKS OF CHLORINATION
7.1. ADVANTAGES
Well-known technology
Broad germicidal spectrum
Residual persistence (residual disinfection)
Biocompatibility (at certain dosages)
Easy and flexible application
Inexpensive
7. ADVANTAGES AND DRAWBACKS OF CHLORINATION
7.2. DISADVANTAGES
Other procedures needed prior to chlorination
Toxicity of byproducts
Limited disinfection efficiency (viruses, cysts)
Adverse environmental impact
Safety and security regulations (transport, storage, and handling)
8. CONCLUSIONS
Chlorination is a well known, effective and versatile
technology for disinfection to be improved in conjunction with ozone and other water treatments in order to achieve safer and more comfortable environments for the aquatic species kept in Aquaria.
9.- BIBLIOGRAPHY
Connell,G.F The chlorination/Chloramination handbook. AWWA,Denver,CO(1996).
Disinfectants and disinfectant By-Products. Proposed Rule.Fed.Reg(July 29,1994)
Fenner,bob.1999. Frequent Partial water changes.FAMA 5/99
Ibañez, Jorge G.; et.al. Microscale environmental chemistry: production of chlorine dioxide.
White, G.C. 1992 Handbook of chlorination, 4 rd.ed.
10.- ACKNOWLEDGMENTS
Akira Kanezaki, for translating this powerpoint presentation even though he doesn’t speak a lick of Spanish.
Allright… some other people at L’Oceanogràfic may have given us a little bit of help, too.
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