2. MICROBIOLOGICAL TREATMENT PROGRAMS FOR COOLING WATER
PRESENTER
H.M.ASIF
MANAGEMENT ASSOCIATE
OPERATIONS UTILITIES

3. OBJECTIVE
To compare various microbiological treatment programs and select the best for our cooling water system.

4. CONTENTS Cooling water system Cooling water problems
Treatment for Microbiological growth
Microbiological growth
Cooling water problems
Cooling water system

5. COOLING WATER SYSTEM Once Through System Open Recirculating System
Closed Recirculating System

6. COOLING WATER PROBLEMS
Scaling
Fouling
Corrosion
Microbial Growth

7. MICROBIOLOGICAL GROWTH
Types of Microorganisms In Cooling Water
Bacteria
Aerobic
Anaerobic
Algae
Green Algae
Blue Green Algae
Fungi
Molds
Yeasts

8. MICROBIOLOGICAL GROWTH MECHANISMS
Binary Fission
Budding
Tip Extension

9. MICROBIOLOGICAL GROWTH CONDITIONS
Nutrients
Sun Light
Temperature Conditions
pH Conditions

10. PROBLEMS BY MICROBIOLOGICAL GROWTH
Formation of Biofilms
Microbiological Induced Corrosion (MIC)
Biofilms on heat exchange surfaces act as insulating barriers. Heat exchanger performance begins to deteriorate as soon as biofilm thickness exceeds that of the laminar flow region.

11. MICROBIOLOGICAL TREATMENT
Oxidizing Biocides
Ozone
Chlorine Dioxide
Chlorine
Bromine
Monochloramines
Non oxidizing biocides
Isothiazoline
Carbamates
Quaternary amines

12. CHLORINATION Adding chlorine gas to water
Cl H2O HOCl HCl
Chlorine Hypochlorous Acid Hydrochloric Acid
Adding sodium hypochlorite to water
NaOCl H2O HOCl NaOH
Sodium Hypochlorite Hypochlorous Acid Sodium Hydroxide
Limitations of Chlorination
- It has high demand
- Increase in chlorides concentration
- Reduced efficiency at high pH values

13. BROMINATION Sodium bromide reacts with hypochlorous acid
NaBr HOCl HOBr NaCl
Sodium Bromide Hypochlorous Acid Hypobromous Acid
Benefits of Bromination over Chlorination.
- Better effectiveness at high pH than chlorine
Limitations of Bromination
- Use with parallel of chlorine
- Increase in chlorides concentration

14. MONOCHLORAMINES Formation of Monochloramine:
HOCl NH NH2Cl H2O
Characteristics of monochloramines
- It has Low demand
- Not affected by suspended solids and organic compounds
- Excellent biofilm penetration and removal
- Effective at wide range of pH
- Effective up to and above temperature of 60 ºC

15. ADVANTAGES OF MONOCHLORAMINES
Elimination of Chlorine
Reduction of Sodium Hypochlorite consumption
Chlorides reduction
Blow down reduction
Reduction in Bulab chemical consumption

16. DISADVANTAGES OF MONOCHLORAMINES
The only disadvantage of Monochloramines is the formation of Dichloramines and Trichloramines. NH2Cl + HOCl NHCl2 + H2O NHCl2 + HOCl NCl3 + H2O

17. CHLORINE VS BROMINE VS MONOCHLORMINES

18. CHLORINE VERSUS MONOCHLORAMINE DEMAND
Residual free chlorine
Residual MCA
Biological matter
Bacteria, Living matter
Reaction with MONOCHLORAMINE
Reaction with
HALO-OXIDANTS
Chlorine, Brimine
Example on cooling water: Chlorine demand: 6.0 ppm MCA demand: 0.3 ppm
Organic matter
Carbon Compounds
Inorganic matter
S,N compounds S N

19. COST COMPARISON FOR Cl2, NaBr & MONOCHLORAMINES

20. CONCLUSION
From the comparison we can say that Monochloramines system is a better choice for the microbiological treatment as:
“It is a more efficient and more economical system”

21. Questions are Welcome ???