Plasma Activated Water: An alternative to chlorine treatment

Introduction - Water treatment is an essential process carried out to improve the quality of water. The process employed for the water treatment depends on the quality of water supply, extent of contamination, end use and applications of water. In majority of the cases, water has to be disinfected to inactivate the microorganisms present in water, which is generally carried out by chlorine and chlorine compounds, ozone, ultraviolet radiation, etc., of which chlorine treatment is used extensively.

- Supreetha. S

However, chlorine treatment results in formation of chlorination by- products which are potentially harmful for human health when consumed and imparts off odour and off taste. Chlorine is not effective against protozoa; it exhibits lower disinfection potential for turbid water and imparts harmful effect resulting from residual chlorine. Hence, there are several studies carried out for application of alternative treatment for water treatment. One such innovative method of water treatment is plasma activated water (PAW).

Plasma refers to partially or completely ionised gas which is a mixture of electrons, protons, ions, free radicals, excited atoms and photons. It is considered as the fourth state of matter along with solid, liquid and gas. Plasma naturally results from lightening; however, it can be produced by creating suitable artificial conditions. Commercially cold plasma is in use due to its efficiency against microorganisms especially on the surface of medical devices, food products and food packaging material.

Plasma activated water (PAW) is generated by application of plasma treatment for water with plasma plume above or below the surface. The plasma generated particles are known to interact with water molecules and trigger several chemical reactions that results in production of a unique mixture of biochemical reactive chemistry that forms PAW. The PAW is produced by injection of the generated plasma into mass of water during which, water droplets are passed through a dielectric barrier discharge or plasma jet. It can also be generated from spark discharge, pin- in water discharge or plasma discharge in water with gas bubbles. Due to its efficiency of microbial reduction, decontamination and disinfection, Treatment of food products and food contact surfaces are carried out using PAW in food industry at various stages of processing and for several intended applications.