The Importance of Microbial Control
Microbiological fouling is one of the most persistent and damaging problems in industrial water systems. Uncontrolled bacteria, algae, and fungi can lead to the development of robust biofilms that dramatically reduce heat transfer efficiency, cause under-deposit corrosion, and harbor dangerous pathogens.
Selecting the best biocides for industrial water treatment systems is vital to maintaining operational efficiency and safety.
Types of Biocides
Biocides are generally categorized into two main types: oxidizing and non-oxidizing.
1. Oxidizing Biocides
These include chlorine, bromine, and ozone. They work by oxidizing the cell walls and internal components of microorganisms. While effective and fast-acting, they can be corrosive to metal surfaces and may degrade other water treatment chemicals like certain phosphonates (e.g., ATMP).
2. Non-Oxidizing Biocides
Non-oxidizing biocides disrupt the metabolic pathways or cell membranes of microbes. They are often more stable, less corrosive, and longer-lasting in the system. Key products in this category include:
- CMIT/MIT (Isothiazolinones): A highly effective, broad-spectrum biocide that works efficiently at low dosages. It is particularly good at penetrating biofilms.
- Benzalkonium Chloride (BKC): A quaternary ammonium compound that acts as both a biocide and a surfactant. Its detergent properties make it excellent for cleaning out existing organic deposits.
- Glutaraldehyde: Known for its rapid action and broad-spectrum efficacy, glutaraldehyde is widely used in highly contaminated systems, including oilfields and cooling towers.
Developing a Biocide Strategy
Because microorganisms can develop resistance if exposed to a single biocide continuously, best practices dictate using a biocide alternation program. By switching between an oxidizing biocide and different classes of non-oxidizing biocides (like alternating CMIT/MIT with Glutaraldehyde), you prevent microbes from building immunity.
Furthermore, regular monitoring using dip slides or ATP testing is necessary to optimize dosing schedules and ensure the system remains under biological control.