Industrial Water Engineering, Inc.

CHEMICAL WATER TREATMENT

toll free 1-800-543-6519

GSA # GS-10F-7884A (1/31/2007)

DOD Cage # 0MV90

 

 

Cooling towers remove  airborne debris from the air that passes through during the cooling process.  In the arid Southwest, mud accumulations of 4 to 8 inches are common within a year. Underneath the mud, bacteria and protozoa thrive.  The mud favors growth of the deadly Legionella pneumophilla bacteria.  Legionella pneumophilla will multiply within the protozoan cells.  Biocides cannot penetrate mud accumulations and control microbiological communities.

Mud may settle within heat exchanger tubes if flow rates are less than 2.5 feet per second.  Once mud accumulates, sulfate reducing bacteria (SRB) grow and cause severe corrosion on mild steel surfaces.

Mud also causes the adsorption of polymers and phosphonates used to prevent mineral scale. Overfeed of chemical treatment is needed to prevent mineral deposits in the system.

Industrial Water Engineering recommends sidestream filtration to remove solids and debris.  Multimedia filters should be used to assure particulate removal to 10 microns. Centrifugal separators are of little effect because filtration is limited to 25 microns.  Bag and cartridge filters are not recommended due to high labor and filter costs associated with  operation.  Filter design must be done to filter the tower volume 24 times per day on normal systems and 34 times per day for systems that have a high amount of airborne contamination.

The filter manufacturer is cautioned to get a water analysis from the water treatment company at tower operating conditions.  For example, towers without supplemental acid feed may contain high levels of alkalinity, chloride, and sulfate. A typical bronze impeller and cast iron body pump will deteriorate and fail quickly in this service.   All vessels should be epoxy lined.