Press Releases


July 27, 2015

Keeping Legionella Bacteria Undetected Without Propagating Them,
Effective New Treatment Using Synergistic Biocides Developed for Legionella
Synergy of Two Types of Agents (Detachment and Bacteria Elimination) Maximizes the Bacteria Elimination Effects

Kurita Water Industries Ltd. (head office: Nakano-ku, Tokyo; president: Toshiyuki Nakai) developed a new and effective treatment for legionella that uses synergistic biocides, as part of the water treatment chemicals business, a groundbreaking bacteria elimination technique for keeping legionella bacteria in the cooling water system at undetectable levels by preventing their propagation.

Cooling towers located in plants and buildings are at risk of circulating water becoming contaminated with propagating legionella bacteria (*). If a person inhales aerosol (misty and fine droplets) of the bacteria, he/she may contract an infectious disease named legionellosis (*).
The guidelines for prevention of legionellosis, formulated by the Ministry of Health, Labour and Welfare, advises that actions such as cleaning and disinfection should be taken immediately after legionella bacteria (100 CFU/100 mL or greater) have been detected. However, we have received strong requests from customers to place greater emphasis on safety and develop a technique that consistently prevents the propagation of legionella bacteria. We consequently sought to develop a technique for dramatically improving legionella bacteria elimination.

The outcome of this effort is this new treatment, an effective treatment for legionella that uses synergistic biocides, which delivers a massive improvement in bacteria elimination with the combined use of a detachment agent for eliminating biofilm (an aggregate consisting of many different microbial species), which can be a hotbed for legionella bacteria, and a bacteria elimination agent for removing legionella bacteria floating in the water.
We have successfully developed a groundbreaking technique for treating legionella bacteria, which identifies the optimal combination of detachment and bacteria-elimination agents to generate synergy among the different functions and maximize the bacteria elimination effects.
The detachment agent has active ingredients that deeply permeate biofilm that may be a hotbed for legionella bacteria. In this way the agent significantly controls the activity of microbial groups including legionella bacteria and eliminates biofilm that attaches to cooling towers and inner surfaces of piping. The bacteria elimination agent delivers fast acting, powerful bacteria elimination performance. By eliminating the legionella bacteria floating in water, the agent helps to maintain an environment in the cooling water that is not tenable for legionella bacteria. Conventional treatment of legionella bacteria generally involves regular input of bacteria elimination agent in high concentrations. This is not sufficient to completely eliminate bacteria and allows them to quickly regrow. In contrast, the new treatment creates an environment in which legionella bacteria cannot propagate and can keep the bacteria at undetectable levels (10 CFU/100 mL or less). The powerful bacteria elimination effect, generated by the synergy, help reduce the amount of chemicals used. Only slightly corrosive to metal, the treatment is economical and does not necessitate use of a special device for controlling chemical concentrations.

From accurate testing for legionella bacteria to bacteria elimination and cleaning in the event the bacteria are detected, and subsequent use of this new treatment to prevent bacterial regrowth, we offer one-stop solutions that maximize the overall strength of our group, as we deliver environments that are always safe and secure for customers.

  • *Legionella bacteria, a species of aerobic gram-negative bacillus, are said to inhabit 40% of cooling towers that do not receive water treatment. By nature, legionella bacteria grow in soil. But the bacteria may enter a cooling tower with dust or similar and/or may propagate in it. If a person inhales droplets of water (aerosol) from a cooling tower that contains legionella bacteria, he/she may develop an infectious disease named legionellosis which takes the form of fever, headache, difficulty breathing and other symptoms.