APPLICATION OF CDD 5000 (0.5% CHLORINE DIOXIDE) IN COOLING TOWER WATER TREATMENT
Cooling tower water treatment is essential for maintaining efficient industrial cooling systems by preventing scale buildup, microbial growth, and corrosion. SVS Aqua’s CDD 5000 (0.5% Chlorine Dioxide) offers a powerful and reliable solution for microbial control, ensuring optimal heat exchange efficiency and system longevity.
CHLORINE DIOXIDE CHEMISTRY FOR COOLING TOWERS
Chlorine dioxide’s chemistry is best summarized not by what it reacts with so much as by what it does not react with variations in pH. Moreover, chlorine dioxide does not react with ammoniacal or most organic contaminants and treatment chemicals present in cooling tower water treatment and wastewater treatment. Moreover, Chlorine dioxide also does not react with ammoniacal or most organic contaminants and treatment chemicals present in the cooling water. Consequently, the dosage required for biocidal control remains fairly constant over a wide range of cooling water conditions. This makes chlorine dioxide an excellent choice for industrial cooling systems, especially those with high pH, or high concentrations of organic or ammoniacal contamination.
For detailed insights on cooling tower regulations, refer to WHO Water Safety Plans.
CHLORINE DIOXIDE APPLICATION IN COOLING TOWER MAINTENANCE
HOW CDD-5000 WORKS FOR INDUSTRIAL COOLING SYSTEMS?
CDD 5000 contains 2 powders A and B:
- Fill the container with the exact amount of tap water as shown on the label (1L, SL, 10L, 50L, etc)
- First, add component A to water in container and then add component B.
- Gently swirl the liquid and securely close the container.
- Wait for 4 hours for reaction to complete.
- After reaction CDD 5000 (0.5 % solution of chlorine dioxide) is ready for use.
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To learn more about the chemistry of chlorine dioxide, visit EPA’s Guide on Disinfectants.
COOLING TOWER WATER TREATMENT METHODS WITH CDD 5000
The primary function of a biocide is to protect the heat exchangers and other metal parts of cooling water treatment solutions. Therefore, chlorine dioxide should be applied directly into the suction of the cooling system’s recalculating pump. Alternatively, it may be applied beneath the water in the sump as close to the pump intake as possible. Depending upon the criticality of the cooling tower water treatment and wastewater treatment, two different treatment schemes may be used; an intermittent treatment scheme and a continuous treatment scheme.
Since both treatment schemes are based upon establishing a chlorine dioxide residual, to be effective the chlorine dioxide demand of the cooling water must be known. Typically the chlorine dioxide demand is determined over a 5-minute time interval. Equation 3 shows the relationship between chlorine dioxide demand, dose, and residual
Residual = Dose – Demand
INTERMITTENT TREATMENT PROGRAM FOR COOLING WATER TREATMENT SOLUTIONS:
An intermittent treatment program may be used for less critical cooling systems. This program applies CDD 5000 three times a day (dawn, dusk, and midnight) at a dose sufficient to achieve a 0.5-1.0 ppm chlorine dioxide residual This dose is based upon the cooling system recirculation rate. The duration of each dosing period is half an hour or four turnovers of the total cooling system volume, whichever is greater.
CONTINUOUS TREATMENT PROGRAM FOR CRITICAL COOLING SYSTEM:
A Continuous treatment program, which is much more expensive, can be used for critical industrial cooling systems. This program applies CDD 5000 continuously at a dose sufficient to achieve e a 0.1-0.2 ppm chlorine dioxide residual. This dose is again based upon recirculation rate.
Learn more about cooling tower disinfection best practices in this Cooling Tower Safety Guide.
CDD 5000 TREATMENT EXAMPLE: INDUSTRIAL COOLING TOWER APPLICATION
The water of an industrial cooling tower with a total system volume of 40 m3.The following table and calculation give the estimated daily CDD 5000 requirement
| SR. No. | DAILY WATER CAPACITY(LIT) | REQUIRED DOSE OF CDD 5000 PER CYCLE(LIT) | CDD 5000 REQUIRED(LIT PER CYCLE) |
|---|---|---|---|
| 1 | 40000 | 0.3 | 2.4 |
| 2 | 40000 | 0.4 | 3.2 |
| 3 | 40000 | 0.5 | 4 |
FORMULA FOR CALCULATING CDD 5000 DOSE:
CDD 5000 required = Required dose rate (PPM) /5000 x Quantity of Water (Lit)
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MICROBIAL CONTROL IN COOLING TOWERS: CDD 5000 ANALYSIS
While CDD 5000 (0.5% chlorine Dioxide) concentrations may be determined by many different methods, two methods have been commercialized. They are in widespread use: the DPD (N,N-diethyl-phenylenediamine method) and the CPR (chlorophenol red method). Since the DPD method is normally used to also determine chlorine concentrations, it is widely available. However, it must be modified so that it reads only chlorine dioxide. In contrast, the CPR method is not as widely used but is specific for chlorine dioxide.
DPD METHOD FOR MEASURING COOLING TOWER WATER TREATMENT EFFICIENCY
Both chlorine and chlorine dioxide react with DPD to give a red–colored solution. The intensity of the red color is proportional to their concentrations. Glycine, NH2CH2COOH, is added prior to the DPD to react with and mask chlorine in the sample. If a test kit calibrated for chlorine is used, the result must be multiplied by 1.9 to correct for the higher equivalent weight of chlorine dioxide.
CPR METHOD FOR PRECISE CHLORINE DIOXIDE MEASUREMENT
The CPR method specifically determines chlorine dioxide concentration based upon its ability to convert red CPR to a colorless product The amount of the red CPR that is bleached is proportional the chlorine dioxide concentration.
CDD 5000 COOLING WATER TREATMENT SERVICES
The implementation and administration of a chlorine dioxide treatment program for cooling tower water treatment and microbiological control requires several different steps. Consequently, many plants find it cost-effective to work with specialized cooling water treatment solutions providers. These companies typically provide the following services:
- Determining the CDD 5000 demand for the water
- Designing, sizing, and providing the right cooling water treatment solutions.
- Optimizing treatment strategies for chlorine dioxide cooling towers.
For more information on industrial cooling systems, explore the Cooling Technology Institute (CTI).
By following a structured approach, businesses can ensure effective microbial control in cooling towers, improve cooling efficiency, and extend the lifespan of their industrial cooling systems.
COOLING TOWER TREATMENT PRODUCTS
- Chlorine Dioxide Cooling Towers
- Cooling Tower Water Treatment Solutions
- Industrial Cooling Systems for Microbial Control
For more details, visit our Chlorine Dioxide Product Page.
