Other filtration techniques
This technology requires no electricity and is effective for TDS up to 500ppm. Whirlpool launched a range of purifiers with this technology in different price categories. The advantage of this technology over RO is that no water is wasted and it also retains essential natural minerals.
Capacitive deionization (CDI) is a technology to deionize water by applying an electrical potential difference over two porous carbon electrodes.Today, CDI is mainly used for the desalination of brackish water, which is water with a low or moderate salt concentration (below 10 g/L). Compared to Reverse Osmosis and Distillation, CDI is considered to be an energy-efficient technology for brackish water desalination.
Distillation removes all the contaminants with higher boiling point than water. In the process, the water is heated until it gets vaporised and the vapour is condensed in another container. The condensed water is almost in its purest form. Distilled water is not recommended for drinking since it lacks any essential mineral. It’s mainly used for laboratory purposes.
Automated Variable Filtration (AVF) technology is a state of the art technology used for wastewater treatment in which upward flow of influent is cleaned by the downward flow of filter media. During the treatment process itself, the filter media is cleaned by the filtered influent thus there is no requirement for any additional filter media cleaning or fresh water. The AVF process comprises two sets of media filters that can be operated in series or in parallel. The two-stage series configuration is used to produce a very high-quality filtrate. This mode is ideal for refining secondary wastewater for reuse.
Germicidal properties of silver and copper can be used to purify water. In this process, electrolysis is carried out using silver electrodes which generate silver ions. Their powerful anti-bacterial properties keep the water pure.
Ozone Water Treatment
Ozone is used in water treatment because of its excellent disinfection and oxidation qualities. Ozone can be added at any stage of water purification. Usually, it is recommended to add before sand filter or active carbon filter. The remaining organic contaminants can be removed by these filters.
Chlorine Water Treatment
Chlorine is a highly efficient disinfectant which is added to water supplies to kill various disease-causing pathogens such as bacteria, virus and protozoa. Chlorination is usually done to disinfect tap water, wells etc. This is a cost efficient method of water disinfection even though it has some disadvantages.
Other Water Softening Techniques
Ion-Exchange resin Devices
Ion exchange resins are organic polymers containing anionic functional groups to which the divalent cations (Ca++) bind more strongly than monovalent cations (Na+). Inorganic materials called zeolites also exhibit ion-exchange properties. These minerals are widely used in laundry detergents. Resins are also available to remove carbonate, bicarbonate and sulphate ions which are absorbed and hydroxide ions released from the resin.
Lime softening is the process in which lime is added to hard water to make it softer. It has several advantages over the ion-exchange method but requires full-time, trained personnel to run the equipment
Chelators are used in chemical analysis as water softeners and are ingredients in many commercial products such as shampoos and food preservatives. Citric acid is used to soften water in soaps and laundry detergents. A commonly used synthetic chelator is ethylenediaminetetraacetic acid.