To protect the public’s health, drinking water and wastewater must be disinfected. To eliminate or render inactive microorganisms (pathogens) that can cause disease in people and animals, all water and wastewater systems should employ some sort of disinfection method. (True. Farms for livestock, pigs, and poultry all rely on good water treatment and sanitation. Clean water is essential for all life as we know it.) Just consider how the general public would never have the opportunity to see the variety of natural aquatic beauty found at aquariums across the world if it weren’t for specialised aquatic life-support systems with extremely sophisticated disinfection processes. Otherwise, water parks, food stores, and space stations would all be impossible. Consider all the different uses of water you encountered this morning simply getting to work: a shower, morning coffee, clean streets, etc. Without some type of disinfection along the route, none of these things would be feasible.

Conventional surface water disinfection is created to balance the impacts of seasonal weather, storm runoff, and source blending on turbidity and total organic compounds while taking into consideration the diversity of the water sources utilised. Systems used may include filtration, clarifying, sedimentation, and flocculation. The nature of these filtering methods permits the removal of the majority of particles larger than a specific size and shape; nevertheless, due to the diversity of the media size and packing density, this is not an absolute removal process. It has been discovered that particular chemicals (such as alum and ferric chloride), cationic or anionic polymers, and oxidation processes contribute to improving process efficiency and the capacity to remove smaller particles to aid in particle reduction. Therefore, enhanced filtration can boost the removal of tiny particles from surface water supplies, such as Cryptosporidium and Giardia, leaving a lesser burden for oxidising biocides or UV for primary disinfection.

The cells of the microorganisms to which they are exposed are attacked by all oxidising biocides, which is how they all function. Because of a structural change in the enzyme, this oxidative interaction alters the permeability of the cell, the protoplasm, or the activity of the enzyme. In some circumstances, the exposure causes the cell membrane to lyse, exposing it to the outside world. In other instances, the oxidant can diffuse through the cell membrane to target RNA and DNA thanks to surface oxidation. The bacterium is either killed or rendered inactive by oxidation, which prevents it from proliferating. The type of oxidant, residual level, contact time, system temperature, and pH all influence the inactivation of microorganisms. The effects of various oxidising biocides on target organisms crucial to public health have been studied by the EPA and other governmental organisations across the world.

The First Law of Photochemistry, which states that only light (photons) received by an organism can effectively produce a photochemical change in the organism, is linked to the efficiency of UV disinfection. UV energy needs to be absorbed in order to inactivate bacteria. The use of ozone and UV technologies allows utilities to use lower chlorination levels for water distribution, which reduces the number of chlorinated disinfection byproducts in drinking water supplies.