How does the ozonation process work?
Ozone is a pale blue gas composed of three oxygen atoms (O3). Ozonation is a water treatment method where ozone is generated on-site and introduced into water to eliminate a wide range of organic compounds and microorganisms. The transformation of oxygen into ozone, a very powerful oxidant, occurs with the use of energy. Inside the ozone generator vessel, ozone is produced from oxygen present in the feed gas by means of a silent electric discharge (non- thermal plasma). Ozone is dissolved into the water. It produces a direct oxidation reaction on the pollutants/molecules.
What are some of the applications for ozonation at water treatment plants?
Ozone is used as a stand-alone technology in some cases. It can also be combined with hydrogen peroxide (H2O2), ultraviolet light, or active chlorine to perform an advanced oxidation process (AOP). This AOP produces highly reactive hydroxyl radicals (·OH). These reactive species are the strongest oxidants that can be applied in water. They are used to address contaminants with high chemical oxygen demand (COD) or non-biodegradable molecules. They also improve the overall quality of the water.
Ozonation can be used to complement chlorine disinfection of drinking water. By using ozone, utilities can limit or avoid the use of chlorine if there’s a concern about dangerous byproduct formation. Ozone also treats groundwater that has been polluted by metals, like iron and manganese, and inorganics, such as hydrogen sulfide (H2S), that are easily oxidated by O3.
What do you know about the threat posed by micropollutants? Do many treatment operations consider them to be a concern?
Endocrine disrupting compounds (EDCs) are chemicals that, at certain doses, can interfere with endocrine systems. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders. Drugs and pharmaceutical residuals are not effectively treated with the traditional wastewater treatment plants.
Switzerland is the first country that has enacted a specific law, but many countries are conscious about this serious concern.
Some countries, like Germany and France, are addressing the micropollutant issue even faster than Switzerland, despite a lack of regulation.