An API is the substance in a pharmaceutical drug that is biologically active. It is the element that provides the therapeutic effect, distinguishing one medication from another. For instance, in a pain relief tablet, the API might be acetaminophen, whereas the remaining ingredients, known as excipients, help to deliver the API effectively but do not exert therapeutic effects themselves.
Beyond chlorination, other disinfectants such as ozone and ultraviolet (UV) light have also gained popularity in chemical water treatment. Ozone, a more potent oxidizing agent than chlorine, can break down organic pollutants and disinfection byproducts. Its short lifespan in water means it must be generated on-site, but it offers an effective alternative, especially in water with high organic load. Meanwhile, UV treatment involves exposing water to UV light, which disrupts the DNA of pathogens, rendering them inactive. This method does not introduce any chemicals into the water, making it a preferred option for many purification processes.