SUEZ Water - Water Technologies & Water

Microbiological Control Agents

Minimize biofouling and microbiologically-induced corrosion (MIC)

Industrial cooling water systems, particularly open recirculating systems, provide a favorable environment for the growth of microorganisms including both planktonic and sessile growth. Without microbiological control, the growth can result in corrosion and other efficiency issues that can cause equipment failure, unscheduled downtime, reduced heat transfer and lost production.

SUEZ offers a broad portfolio of oxidizing and non-oxidizing biocides as well as biodispersants to treat and protect cooling system from a variety of micro-organisms and microbiological growth.

Featured Products

Spectrus* Microbiological Control Agents

Spectrus products give customers a wide array of options for controlling microbes (algae, fungi, bacteria, protozoa, etc.) and macrofouling organisms (mollusk) in cooling water and related industrial systems. Control of biological populations in industrial water systems is essential to prevent biofouling and other microbiological growth-related issues.

The Spectrus product line consists of the following product series:

  • Spectrus BD: to enhance the biocide performance
  • Spectrus CT: to address macrofouling organisms
  • Spectrus DT: detox materials
  • Spectrus NX: non-oxidizing biocides
  • Spectrus OX: oxidizing biocides

Microbiological Fouling

What is microbiological fouling?

Microbiological fouling in cooling systems is the result of abundant growth of algae, fungi, and bacteria on surfaces. Once-through and open or closed recirculating water systems may support microbial growth, but fouling problems usually develop more quality and are more extensive in open reticulating systems.

Once-through cooling water streams generally contain relatively low levels of the nutrients essential for microbial growth, so growth is relatively slow. Open recirculating systems scrub microbes from the air and, through evaporation, concentrate nutrients present in makeup water. As a result, microbe growth is more rapid. Process leaks may contribute further to the nutrient load of the cooling water. Reuse of wastewater for cooling adds nutrients and also contributes large amounts of microbes to the cooling system.

In addition to the availability of organic and inorganic nutrients, factors such as temperature, normal pH control range, and continuous aeration of the cooling water contribute to an environment that is ideal for microbial growth. Sunlight necessary for growth of algae may also be present. As a result, large, varied microbial populations may develop.

The outcome of uncontrolled microbial growth on surfaces is "slime" formation. Slimes typically are aggregates of biological and nonbiological materials. The biological component, known as the biofilm, consists of microbial cells and their by-products. The predominant by-product, extracellular polymeric substance (EPS), is a mixture of hydrated polymers. These polymers form a gel-like network around the cells and appear to aid attachment to surfaces. The nonbiological components can be organic or inorganic debris from many sources which have become adsorbed to or embedded in the biofilm polymer.

Slimes can form throughout once-through and recirculating systems and may be seen or felt where accessible. In nonexposed areas, slimes can be manifested by decreased heat transfer efficiency or reduced water flow. Wood-destroying organisms may penetrate the timbers of the cooling tower, digesting the wood and causing collapse of the structure. Microbial activity under deposits or within slimes can accelerate corrosion rates and even perforate heat exchanger surfaces.

Microbial Control

What is Microbial Control Growth?

Scale deposits are formed by precipitation and crystal growth at a surface in contact with water. Precipitation occurs when solubilities are exceeded either in the bulk water or at the surface. The most common scale-forming salts that deposit on heat transfer surfaces are those that exhibit retrograde solubility with temperature. 

Although they may be completely soluble in the lower-temperature bulk water, these compounds supersaturate in the higher-temperature water adjacent to the heat transfer surface and precipitate on the surface.

Scaling is not always related to temperature. Calcium carbonate and calcium sulfate scaling occur on unheated surfaces when their solubilities are exceeded in the bulk water. Metallic surfaces are ideal sites for crystal nucleation because of their rough surfaces and the low velocities adjacent to the surface. Corrosion cells on the metal surface produce areas of high pH, which promote the precipitation of many cooling water salts. Once formed, scale deposits initiate additional nucleation, and crystal growth proceeds at an accelerated rate.

Scale control can be achieved through operation of the cooling system at subsaturated conditions or through the use of chemical additives.