Water purification is the process by which water is treated so that it can be consumed by human beings without there being a risk to health. Consumption can refer to drinking and in the preparation of food.
Purification consists mainly of eliminating substances that are toxic to people, such as chromium, lead and zinc, as well as algae, sand or bacteria and viruses which can be present in water. In essence, it aims to eliminate any potential risk to the health of people.
Water is purified in what is technically known as a DWTP or Drinking Water Treatment Plant. This commonly refers to facilities such as water purification plants.
The water purification process varies according to the natural features of the terrain. For example:
Although, as we have seen, purification processes differ according to each situation, there are some stages that are common to all treatment, as follows:
The first step consists of eliminating large solids. A grill is inserted to filter out fish and branches. Then, with the help of a desander, sand is separated from the water to avoid damaging pumps in the drinking water plant. In this stage, a pre-disinfection is also usually carried out to destroy various organic substances.
Low-pressure pumps transport the water to a mixing chamber where the elements that purify the water are incorporated. In this stage of the purification process, the pH is adjusted by adding acids or alkalis and coagulating water agents.
In the decanter, suspended particles in the water are separated by gravity. The denser harmful sediments remain at the bottom, where they are eliminated, and the least dense continue dissolved in the decanted water.
After the decantation process, the water is passed through a porous medium to eliminate the least dense sediment. These filters strain out impurities. There are different kinds of filters, such as sand or activated carbon, and these can be open and work by gravity, or closed and work through pressure.
Finally, chlorine is added to eliminate any kind of bacteria or virus. If it is necessary to eliminate pathogens from underground water or natural springs, this can be done through ultraviolet radiation or by applying ozone, for example.
Once the DWTP process has completed, it is indispensable that various analyses of the water are performed in order to ensure that the purification process has been successful. Potable water must be colorless, odorless and insipid, and comply with the regulations in force in each country.
ACCIONA undertakes the management of end-to-end services which involve all the stages involved in water treatment: readying it for human consumption, supplying it to the population, then cleaning up urban and industrial waste water. The company also takes care of invoicing end users.