Water treatment describes processes that make water more acceptable for a use, which may be domestic or industrial. Water treatment should remove existing water contaminants or so reduce their concentration that their water becomes fit for its desired use, which may be safely returning used water to the environment.
The processes involved in treating water may be solids separation using physical processes such as settling and filtration, and chemical processes such as disinfection and coagulation.
Biological processes are employed in the treatment of waste-water and these processes may include, for example, aerated lagoons, activated sludge or slow sand filters.
Potable water purification
Water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for the most critical of its intended uses, usually for human consumption. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, minerals such as iron, manganese and sulphur, and other chemical pollutants such as fertilisers.
Measures taken to ensure water quality not only relate to the treatment of the water, but to its conveyance and distribution after treatment as well. It is therefore common practice to have residual disinfectants in the treated water in order to kill any bacteriological contamination during distribution.
World Health Organisation (WHO) guidelines are generally followed throughout the world for drinking water quality requirements. In addition to the WHO guidelines, each country or territory or water supply body can have their own guidelines in order for consumers to have access to safe drinking water.
Drinking water treatment:
A combination selected from the following processes is used for municipal drinking water treatment worldwide:
- Pre-chlorination – for algae control and arresting any biological growth.
- Aeration – along with pre-chlorination for removal of dissolved iron and manganese.
- Coagulation – for flocculation.
- Coagulant aids, also known as poly-electrolyte – to improve coagulation and for thicker floc formation.
- Sedimentation – for solids separation, that is, removal of suspended solids trapped in the floc.
- Filtration – removing particles from water.
- Desalination – Process of removing salt from the water.
- Disinfection – for killing bacteria.
There is no selection of processes for any type of water. Also, it is difficult to standardise the solution in the form of processes for water from different sources. Treatability studies for each source of water in different seasons need to be carried out to arrive at most appropriate processes.
Industrial water treatment:
Industrial Water Treatment can be classified into the following categories:
- Industrial waste-water treatment
- Boiler water treatment
- Cooling water treatment
- Sewage treatment
I will discuss above points later in my blog.