E.C.T. Offshore Service, in conjunction with Wecantech, has developed a chlorine dioxide (ClO2) reaction system to combat bacterial agents in water systems and safeguard the health of offshore workers.
Offshore vessels and facilities are very different from onshore structures. They are isolated, relatively closed communities and difficult to service quickly. This means that contagious health problems with the crew can escalate in severity and cost to the operator. There are many potential sources of infection. Pathogens can be transmitted through the air, by "carrier" individuals during crew changes, through food, or by contaminated water.
This places special demands on the heating, ventilation, and air conditioning system, which controls the interior environment of the offshore facility. Under certain conditions, it can become the primary path for bacterial and viral contamination. Legionella (Legionnaires' disease) and Coliform bacteria are two of the most serious infective agents that need to be controlled.
ClO2 is an oxidizing agent rather than a chlorination agent. It is widely used onshore to disinfect municipal water systems and to control odor and taste problems. It is used in the paper and pulp industries as a bleaching agent, by food processors as a disinfectant, and for slime control in the treatment of industrial water systems. Even medical wastes are neutralized with ClO2.
ClO2 is effective as a disinfectant at concentrations as low as 0.1 ppm and over a wide pH range. As a biocide, it penetrates the bacterial wall and reacts with amino acids in the cytoplasm to kill the organism. Though reactive, it is safe and environmentally friendly when handled properly. It is also a pollution protection technology because it does not produce dioxin, a by-product of chlorination systems. ClO2's by- product is chloride, a simple salt that poses no threat to human beings.
Pure ClO2 cannot be purchased in solid, liquid, or gaseous form because of its reactive nature. It must be produced on site for application to the water system needing treatment. Solutions of 1% ClO2 can be safely stored at 5° C in special containers for several months, with little change in concentration.
The reactor systems available from E.C.T. Offshore produce ClO2 by mixing hydrochloric acid and sodium chlorite or chlorine and sodium chlorite to generate ClO2 in the concentrations required. Dosing of water systems is usually done one of two ways: continuously for permanent system disinfection or on-demand to treat an infected system. E.C.T. provides both permanent disinfectant systems as well as portable systems for sanitation of infected systems.
In The Netherlands, the government demands that samples be taken for Legionella and Coliform bacteria in potable water systems. To protect potable water systems from Legionella and Coliform bacteria, continuous treatment is recommended. If an outbreak of disease occurs, the complete water system will need to be cleansed and disinfected. All "dead ends" will need to be opened, flushed, and tested. This includes humidifiers, air conditioners, ice machines, cleaning systems, and washing machines.
For more information, contact Yvonne Putzig, E.C.T. Offshore Service. Tel: +46 31 53 00 40, fax: +46 31 53 00 45, email: [email protected].
