Biological Control and Biocides

Cooling water towers and other industrial process waters can be ideal breeding grounds for biological growth, including algae, bacteria, sulfate-reducing bacteria, protozoa, and fungi. If not properly controlled, these organisms will form a layer of bio-slime that acts as a natural adhesion surface for mineral scales and debris, resulting in increased corrosion rates, restricted water flow, and reduced system efficiency.

ChemTreat engineers begin the development of a biological control program with a thorough survey of the key water systems to determine the categories of biological control necessary. This information allows the engineer to select a customized treatment program to produce the most effective microorganism control. Other considerations include:

  • The volume of the water being treated as measured through a molybdate-tracer program or the system piping.
  • The recirculating water pH to ensure the water is compatible with the selected biocide chemicals.
  • Other system operational details such as metallurgy, operating temperatures, hydrology, dead legs, and environmental concerns.

Once the treatment program is initiated, our engineers can periodically monitor the biological activity, as biocides may need to be alternated to provide the best treatment. ChemTreat is proud to offer a complete portfolio of biocide products for controlling both macro/mollusk and microbiological growth.

Oxidizing and Nonoxidizing Biocides

Oxidizing Biocide Treatments

These compounds oxidize protein groups on and within the cell, resulting in the loss of normal enzyme activity necessary for respiration and cell metabolism. Chlorine is the most widely used oxidizing biocide and is applied in most cooling and process waters that operate below pH 8. Bromine-based biocides are more effective at higher pH levels, making them ideal for use in systems that operate above pH 8, up to pH 9. Oxidizing biocides include stabilized sulfamates, isocyanurates, slow-release hydantoins, and chloramine-based biocides.

Nonoxidizing Biocide Treatments

When oxidizers alone are insufficient to control microbial growth, or if halogen-based biocides cannot be used, nonoxidizing biocides can be added. These products operate via different mechanisms than those of oxidizing biocides and require specific considerations during product selection. System pH, temperature, biofilm presence, and contaminants like ammonia or sulfide should be considered when selecting the appropriate nonoxidizing biocides. Unlike oxidizing biocide programs, nonoxidizing treatment needs to be reassessed over time to correct for natural variations that may occur in the system.

Combining Oxidizing and Nonoxidizing Biocides

Combining oxidizing biocides with nonoxidizing biocides provides optimal microbial control to address biofouling in difficult-to-treat systems. A comprehensive approach to microbial control can result in:

  • Unsurpassed bulk water cleanliness
  • Improved biofilm control
  • Improved heat exchanger cleanliness
  • Optimized treatment costs

ChemTreat has demonstrated success with our approach to microbial control in a wide array of cooling and process waters, including in industries such as power, primary metals, pulp and paper, food and beverage, oil fields, and refining. ChemTreat also provides support to address concerns about Legionella bacteria growth through Legionella control programs tailored to help meet the specific needs of your facility.

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