In industrial water treatment, maintaining maximum heat transfer is essential for optimal system performance.  It is crucial that the surfaces of the heat exchangers or chillers in these systems are free of fouling.  The presence of biofilm on these critical surfaces disrupts heat exchange and has a menacing effect on the system’s efficiency.

Allowing biofilm bacteria to reproduce and grow thicker biofilm deposits further chokes heat efficiency and compounds the problems manifested in the cooling water system.  This article will explain the numerous issues caused by even low levels of biofilm deposits and offer a simple solution to remedy and avoid the perils of biofilm formation in cooling water systems.

Understanding Biofilm’s Negative Impact

There are many foulants that negatively impact the efficiency of cooling water systems including corrosion-by-products, mineral scales, process fluid deposits, air and water-borne dirt and debris, and biofouling deposits.  When surface deposition occurs on heat exchange surfaces, heat transfer is impacted negatively.  In addition to the loss of heat transfer, other detrimental effects include:

• Increased energy consumption to achieve needed cooling and higher utility bills.
• A higher risk of under deposit corrosion causing pitting in the metal and weakening the system metals overall.
• Compromised product quality due to inadequate cooling.
• Elevated chemical usage to maintain control of the system.

By far, biofilm deposits have the lowest thermal conductivity of the many foulants that plague cooling water systems.  Even a thin layer of biofilm can drastically reduce the cooling capacity of a heat exchanger or chiller.  For example, a mere 100 micron (0.1mm) layer of biofilm on a typical copper chiller tube can reduce the conductive heat transfer by 98%!

The chart below illustrates how biofilm is more of an insulator than calcium carbonate.

(Check out the AMSA Technical brief, Biofilm’s Impact on Cooling, for more details and heat transfer formulas.)

The Cost of Poor Scale and Biofilm Control

If your cooling water systems do not have good scale and biofilm control, your treatment programs are costing your customers extra money! As the chart above illustrates, even thin layers of scale and biofilm negatively impact heat exchange. When a system delivers less cooling, more energy is needed to deliver the required level of cooling. The table below shows the cost of the extra energy needed to deliver cooling when varying levels of scale are present on heat exchanger tubes. The formulas are based on rated chiller efficiency of 0.61 kW/ton, annual operation of 3000 hrs/year and energy costs of $0.09/kW-hr.

Using the same chiller efficiency, annual operation hours and energy costs, the varying thicknesses of biofilm require a greater amount extra energy to deliver the needed heat exchange which causes the cost of running the system to increase greatly!

These charts clearly illustrate the importance of maintaining an effective biofilm control program in a cooling water system. Even a layer of organic deposits as thin as 0.2 mm increase the cost of the energy needed to deliver cooling by a significant amount!

Note: The economic data charts are excerpts from ‘“Cooling Systems: Increased Costs from Mineral Scaling and Biological Fouling” by Innovas Technologies.

Organic Deposit Dispersant Chemistries are an Easy and Effective Solution to Remove and Prevent Biofilm Deposits

Many water treatment professionals commonly use a higher dose of biocide to combat decreased heat transfer caused by biofilm deposits will get a system back in control.  However, this does not get at the root of the issue. Using high concentrations of oxidizing biocides can increase corrosion rates, and may degrade sensitive corrosion and scale inhibitors.  This results in greater use of these chemicals and increases the cost of the treatment program.

A better choice is to use a dedicated organic deposit penetrant/cleaner chemistry that has a direct impact on the biofilm deposits.  AMSA’s Biofilm Control Program (BCP®) products are especially effective at penetrating deeply into biofilm deposits and breaking them apart.  This results in removing biofilm deposits from surfaces and preventing them from reforming.  Adding AMSA’s chemistry to your water treatment program will allow your biocide and inhibitor chemicals to do their job more effectively.  It will also help you give the customer an optimally performing cooling water system with better corrosion control.

Take Control of Your Cooling Water System with the Cleaning/Dispersant Action of AMSA BCP® Chemistry

Adding AMSA BCP® Chemistry, containing DTEA II®, to your water treatment program is an easy and effective solution for cleaning fouled system surfaces.  More importantly, using AMSA products as a regular component of your overall water treatment program will keep your cooling water system clean which results in superior heat transfer and corrosion control while requiring less biocide and corrosion and scale inhibitor chemicals.

Do not be lulled into thinking your water treatment program is doing an adequate job only to find your customer won over by another water treatment company that offers higher cooling efficiency and better corrosion control.  Take proactive steps to safeguard your customers’ systems again biofilm-related challenges with AMSA products.  Contact us today to learn more about our products and schedule a free consultation to elevate your standard water treatment program to a superior Biofilm Control Program.