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chlorination in aquaria

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 .

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chlorination in aquaria

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    1. CHLORINATIONIN AQUARIA MÓNICA VALLS, NÚRIA GIL, PABLO AREITIO Parques Reunidos Valencia, S.A. L’Oceanogràfic. Junta de Murs i Valls, s/n 46013 Valencia, Spain. ngil@oceanografic.org

    2. 1. INTRODUCTION CHLORINATION AS WATER TREATMENT The most widely-used technique of water disinfection in aquatic facilities. First modern application: Disinfection in hospitals (1846)

    3. 2. CHLORINE AND ITS FORMS2.1. THE CHLORINE “Chloros”: Greek translation of green Atomic symbol: Cl2 Halogen family Abundant element in nature (NaCl) Strong oxidant: Disinfection applications The title on this slide and the next are different, yet both are designated 2.The title on this slide and the next are different, yet both are designated 2.

    4. 2. DEFINITION OF CHLORINE & CHLORINATION2.2. COMMONLY USED FORMS OF CHLORINE

    5. 3. CHLORINATION & ITS CHEMISTRY3.1. 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

    6. 3. CHLORINATION & ITS CHEMISTRY3.2. CHLORINE SUPPLY AND CHEMISTRY

    7. 3. CHLORINATION & ITS CHEMISTRY 3.2. CHLORINE SUPPLY AND CHEMISTRY A. Ex situ: iChlorine gas iCalcium hypochlorite iSodium hypochlorite iChlorine dioxide

    8. 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

    9. B. In situ: Principle: Electrolysis 2NaCl + 3H2O g NaOCl + HOCl + NaOH + 2H2 Generators -Electrolytic battery using titanium anodes -Dependent on electricity & water quality

    12. 3. CHLORINATION & ITS CHEMISTRY3.3. 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

    13. pH: Cl2 + H20 n HClO + H+ + Cl- n H+ + ClO- 3. CHLORINATION & ITS CHEMISTRY3.3. FACTORS AFFECTING CHLORINATION

    14. 4. BIOLOGICAL EFFECTS 4.1. POSITIVE EFFECTS DISINFECTION ORGANIC MATTER OXIDATION 4.2. NEGATIVE EFFECTS SHORT TERM EFFECTS LONG TERM EFFECTS Is this one necessary?Is this one necessary?

    15. 4. BIOLOGICAL EFFECTS4.1. POSITIVE EFFECTSDISINFECTION 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)

    16. 4. BIOLOGICAL EFFECTS4.1. POSITIVE EFFECTSDISINFECTION

    18. 4. BIOLOGICAL EFFECTS4.1. POSITIVE EFFECTSDISINFECTION

    19. 4. BIOLOGICAL EFFECTS4.1. POSITIVE EFFECTSORGANIC 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.

    21. 4. BIOLOGICAL EFFECTS4.2. NEGATIVE EFFECTSSHORT 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

    22. 4. BIOLOGICAL EFFECTS4.2. NEGATIVE EFFECTSLONG 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

    23. 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

    24. 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 Underlines and bolds correct on this page?Underlines and bolds correct on this page?

    25. 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

    26. 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 Due to overdosing?Due to overdosing?

    27. 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

    28. 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)

    29. 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. 7. Could be conclusions, no?7. Could be conclusions, no?

    30. 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.

    31. 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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