Water Treatment can be defined as a process of eradicating harmful chemicals, suspended solids and any other contaminants to ensure water is fit for human consumption. As per a recent report, more than 780 million people worldwide do not have access to clean drinking water making water borne diseases and more particularly diarrhea the biggest killer in underdeveloped countries.
Water is an excellent solvent and this property renders it vulnerable to contamination from various sources.
Rapid and unplanned urbanization and industrialization is increasingly resulting in contamination of water sources. There is need for deployment of advanced technologies with capacity for large scale water treatment. Affordable water treatment techniques are a must since water contamination causes water borne diseases which are reported mostly from the underdeveloped and developing countries.
Water treatment nowadays is very widely used to ensure clean water, not only for drinking but a host of other applications. Water treatment can involve any or all of the processes of Filtration and distillation, chemical treatment by way of chlorination and ultra violet or UV technology as well as sand filtering. The choice of treatment depends on the quality of water to be treated and the end user application of water. Ground water is generally of higher quality and requires lesser treatment than water originating from lakes, rivers and streams.
Water Treatment basically involves the following steps
- Coagulation is the first step in the process and the purpose is to get rid of dirt and other suspended particles in water. Water is treated with chemicals like Alum etc which form sticky particles called floc. Floc attracts the dirt pieces which stick to it like magnet and their combined weight settles at the bottom of the water.
- Floc along with dirt is then be removed by Sedimentation. The clear water goes ahead for filtration.
- Filters made of layers of sand; gravel and charcoal are used to remove smaller suspended particles from water. Filtration can be done in various ways, some of the common ones being:
- Coarse filtration or particle filtration is done by using a wide range of material from a 1 mm sand filter to even a 1 micron cartridge filter.
- Micro filtration is done to remove bacteria by using 1 to 0.1 micron devices, typically used in the brewing process.
- Ultra filtration helps remove pyrogens, endotoxins, DNA and RNA fragments.
- Reverse osmosis is the most technologically advanced filtration technique mechanism with capability to separate molecular sized particles by using a porous material.
- Distillation is done to get rid of bacteria and other microorganisms present in water by adding small amounts of chlorine or any other disinfection.
Water is then stored in a closed tank or reservoir to give sufficient time for disinfection to happen. Once disinfection is complete, it is released for to be used consumed either domestically or commercially.
It is difficult to standardize a common solution to treat water. The selection of the treatment process depends upon both the source of water as well as the season in which the treatment is to be undertaken.