Ozone (O3) is a molecule consisting of three oxygen atoms, formed when oxygen is exposed to energy sources like ultraviolet light or electrical discharge. It is widely employed to remove impurities and harmful microorganisms from various water sources. Ozone’s primary function in water treatment involves its ability to oxidize and break down unwanted substances.
The Science Behind Ozone Disinfection
Ozone operates as a powerful oxidizing agent in water treatment. When ozone is introduced into water, its unstable molecular structure, with three oxygen atoms, sheds one oxygen atom to form a stable two-atom oxygen molecule (O2). This process releases a highly reactive single oxygen atom, which rapidly interacts with contaminants through oxidation.
Disinfection involves the direct oxidation of microbial cell components. The reactive oxygen atom attacks and breaks down the cell walls and membranes of bacteria, viruses, and protozoa, leading to their disintegration. This cellular damage, known as cell lysis, inactivates the microorganisms and prevents reproduction. The speed of this oxidation contributes to ozone’s effectiveness as a disinfectant.
What Ozone Removes from Water
Ozone targets a broad spectrum of contaminants. It inactivates microorganisms, including bacteria (E. coli, Salmonella), viruses, and protozoa (Giardia, Cryptosporidium). Many of these pathogens resist other common disinfectants.
Beyond microorganisms, ozone oxidizes organic compounds causing undesirable taste, odor, and color, such as sulfur, geosmin, and 2-methylisoborneol (MIB). It also treats inorganic substances, converting them for easier filtration. This includes oxidizing soluble iron and manganese into insoluble particles, and removing hydrogen sulfide.
Why Ozone is Used for Water Treatment
Ozone is used for water disinfection due to several advantages. It is effective against a wide range of pathogens, including those resistant to chlorine. Ozone reacts quickly with contaminants, leading to rapid disinfection.
A benefit of ozone is its ability to reduce harmful disinfection byproducts (DBPs) like trihalomethanes (THMs), often associated with chlorine. Ozone naturally decomposes into oxygen after reaction, leaving no chemical residues or taste and odor. This improves water aesthetics, including clarity, taste, and odor, without residual chemicals.
Applications of Ozone Water Treatment
Ozone water treatment is applied across various settings and industries. Municipal drinking water plants use ozone to ensure safe water for communities, eliminating pathogens and improving quality.
In industrial sectors, ozone treats wastewater in food, beverage, and pharmaceutical manufacturing. It purifies process water and treats effluents before discharge, aiding environmental compliance. Ozone is also used in recreational facilities like swimming pools and spas for clarity and sanitation. Aquaculture benefits from ozone’s ability to disinfect and oxidize organic pollutants, improving water quality.