Purified water for irrigation (VI). Disinfection

The disinfection of treated water means the removal, deactivation or elimination of pathogenic micro-organisms in the water.

Disinfection is achieved by chemical and/or physical disinfectants. These agents remove organic contaminants from the water, which are nutrients for micro-organisms. Disinfectants must not only kill the micro-organisms but must also have a residual effect, which means that they remain as active agents in the water after disinfection to prevent the growth of micro-organisms in the irrigation pipes.

In 1680 Anthony van Leeuwenhoek developed the microscope and the discovery of micro-organisms was considered a curiosity. It would be another two hundred years before scientists would use this invention, the microscope, for the identification and comparison of micro-organisms and other pathogens.

Chemical disinfectants include chlorine and ozone, but physical disinfectants include ultraviolet light, electronic radiation, gamma rays, heat, etc....

Chlorine disinfection is based on the oxidation power of free oxygen atoms and chlorine substitution reactions. Depending on the pH of the water, the chlorine will be in the form of hypochlorous (optimal disinfection), if we are in the range of 5.5<pH<7.5, or in the form of hypochlorite (deficient disinfection) when we are close to pH 8. At pH 7.5 the concentrations of one and the other are equal. The doses are conditioned by the amount of organic matter in the water, pH, contact time and temperature. As a reference for treated wastewater: 2 to 8 ppm.

Disinfection by ultraviolet radiation is a physical procedure, which does not alter the chemical composition. The most germicidal radiation is that with a wavelength of 254 nm. DNA exposed to this energy shows a maximum absorption, resulting in an irreversible inactivation of germ growth. The safety of U.V. disinfection is scientifically proven and constitutes a safe, effective, economical and environmentally friendly alternative to other disinfection methods such as chlorination. The benchmark for lamp replacement costs is around 0.00674 Euro/cubic metre.

The ozone molecule, O3, is formed by the bonding of an oxygen molecule with a free oxygen atom. The free atoms, and consequently the ozone, are the result of the dissociation of the oxygen molecules when they are subjected to a strong electrical discharge. By means of ozone we can reduce the organic load of the water, as well as oxidising and adjusting turbidity, suspended solids, etc... Ozone generators form an ozone stream by means of the oxygen in the air, which is injected into the water to be treated.

If you need more information about water disinfection, please do not hesitate to contact us and we will be happy to explain how this procedure can help your golf course or football pitch.