Unfortunately, there is no hard and fast guide available which will accurately predict which biocide(s) to select to ensure continuous, effective microbiological control in the many different types of systems available. Effective biocide programs are often based on trial and error, coupled with previous experience and supported by appropriate technical advice.
Part of the reason for the range of biocidal products is that the problems of fouling, potential health hazards and microbiological induced corrosion in open cooling systems and closed systems remain difficult to control successfully and continuously.
A large number of factors will need to be considered in order to ensure optimal control in any open or closed system where microbial contamination is an issue or a potential issue.
Considerations should include:
- Existing corrosion, deposits and other reported problems in the system to be treated.
- The results of any microbiological analyses carried out. Microbiological counts (TVC’s), SRB's, biofilms, etc.
- In the case of a closed systems the temperature and pH of system water should be known
- Use of bio-dispersants in conjunction with the selected biocide may be required.
- Proposed and previous biocide application rates and frequency.
- In the case of open systems, retention time and water velocity through the system.
- Cooling system pH, chlorides, TDS, or other pertinent analytical parameters, including any process contaminant load or cooling system nutrients.
- The compatibility and possible effects on chemical inhibitors or other chemicals present in the system.
- Cost comparisons of proposed biocide treatments.
The above range of considerations effectively illustrates the fact that every system, whether open or closed, will be different in its operating considerations and will contain a different range of micro-organisms. Some systems will be problematic and even after trying a number of biocides it may prove impossible to bring the bacterial levels within a system under control.
There are a number of ways of testing biocides and measuring their efficacy but our laboratory based biocide evaluations have been specifically designed to mimic the conditions of the system on site. By carrying out a biocide evaluation on actual system water we are able to give our customers guidance on which biocides are likely to be the most effective in their problematic systems.
For further guidance on our biocidal evaluations and costings please contact our technical team.
