Water purification is a procedure that removes pollutants from water, such as toxins, inorganic compounds, and germs, leaving it cleaner, usable and drinkable.

As impurities are eliminated and then contamination is handled.

Water contains various impurities in its natural form, including bacteria, organic and inorganic chemicals, particles, dissolved gases, and many others. Visual examination will never reveal the cleanliness or impurity levels of water. A microbiological study is required for a more thorough investigation.

Conventional Water Purification Techniques

There are many different kinds of purification methods that can be used to make water pure, often in combination. The technology best suited for you depends on the application you water.

wastewater tank
Industrial wastewater storage tank in the countryside

Activated Carbon (Absorption)

The adsorption of pollutants onto the surface of a filter is the foundation of activated carbon filtration, which is the most used technique. This approach is efficient for removing some organics (unwanted taste and odours, micropollutants), chlorine, fluoride, and radon from drinking water or wastewater. Microbial pollutants, metals, nitrates, and other inorganic contaminants are not affected. The kind of activated carbon employed, the water composition, and the operating settings influence adsorption efficiency. 


Electrodeionization (EDI) is an electrically-driven water treatment process that removes ionised species from water using electricity, ion exchange membranes, and resin. Ions and other charged species, such as salts and organic acids, are removed from water using EDI.

Ion Exchange

Ion exchange is a chemical method in which undesired soluble particles in water such as nitrate, fluoride, sulphate, and arsenic, are replaced for similar-charged ions. Ions are tiny particles in which the total number of electrons exceeds the total number of protons.


pressure pipes
steel pipes with pressure gauge used in water filtration

Pressure filtration is not so commonly used filtration process in which the water to be filtered is pushed through filtering material at a pressure greater than the filter’s weight.

Reverse Osmosis(RO)

Reverse osmosis (RO) is a water filtration method that separates ions, undesirable compounds, and bigger particles from drinking water using a partly permeable membrane. As a consequence, the solute is trapped on the pressured side of the membrane while the pure solvent is permitted to flow through.

Sub-Micron Filtration

Filters function similarly to sieves because they create a tangible border for particle movement depending on pore diameter while enabling water molecules to pass through. To eliminate gross particulates, pre-treatment may also include one or even more filters with pore sizes range of 1 – 100 microns, and inside the water treatment system, sub-micron filtration – microporous filters (0.05 to 0.22 micron) or ultrafilters – are used to remove contaminants such as fine particulates, colloids, and bacteria (0.001 to 0.01micron).

Ultraviolet (UV)

Ultraviolet radiation with a wavelength of 253.7 nanometers is used in the UV water cleaning techniques to kill bacteria, viruses, moulds, algae, and other microorganisms that replicate and develop. UV disinfection kills bacteria by destroying their DNA, turning them lifeless and unable to reproduce. Drinkable water decontamination treated water disinfection, sewage disinfection, as well as surface disinfection can all benefit from the UV disinfection techniques.

Latest Water Purification Technologies

To better serve their clients, worldwide water purification manufacturers are investigating cutting-edge water filtration innovations such as carbon nanotubes and sophisticated membrane systems.


Synthesis of nanoparticles
Schematic illustration of the in situ synthesis (A) of silver nanoparticles on nano-silica support (NSAgNP) by protein extract, (B) immobilization of protein-coated silver nanoparticles on nano-silica support by the ‘post-deposition route.

Nanotechnology includes a variety of methods and technologies for modifying elements at the atomic or molecular level. When compared to traditional water filtration procedures, nanotech-based water purification processes are thought to be modular, extremely efficient, and are budget-friendly.

Silver, copper, and zero-valent iron (ZVI) nanoparticles, nanostructured photocatalysts, nano-membranes, and nano adsorbents are some of the most common nanotechnologies used in water treatment.

Nanoparticles’ huge surface to volume ratio increases chemical and biological particle absorption while allowing pollutants to be separated at extremely low concentrations. For the extraction of metallic contaminants from water, nano adsorbents have special physical and chemical characteristics.

Carbon nanotubes (CNTs) are the most widely utilised nanomaterials in water purification. Organic, inorganic, and biological pollutants may all be removed from water using CNT-based filtering devices.

Membranes composed of nanoparticles are being developed by global firms such as Alfa Laval, Applied Membranes, DowDuPont, GEA Group, Inopor, Koch Membrane Systems, and others to remove pollutants throughout the treatment process.

Acoustic Nanotube Technology

Acoustic nanotube technology was developed by Nasa scientists first at Johnson Space Center. It directs water through small-diameter carbon nanotubes using acoustics rather than pressure.

Nanotube filtration device
picture depicting how carbon nanotube devices work

The system is based on an acoustically driven molecular screen containing carbon nanotubes that allows water molecules to flow through while restricting bigger molecules and contaminants. It uses less energy than standard filtration systems and instead of eliminating impurities from water, it moves water away from them. The technique also removes the requirement for the filter system to be flushed.

Municipal water plants, medical facilities, labs, distilleries, desalination plants, industrial facilities, wastewater treatment plants, and the consumer segment are the principal uses of acoustic nanotube technology. With the incorporation of numerous filters, the invention is extensible to the individual’s filtering demands. The businesses may licence Nasa’s protected acoustic nanotube technology and turn it into a commercial water filtration solution.

Photocatalytic Water Purification Technology

Photocatalysis for water filtration has gained a lot of popularity due to its effectiveness in purifying polluted water. Toxic chemicals are removed from water using a photocatalyst and ultraviolet (UV) radiation.

Photocatalytic water treatment
Stepwise illustration of the photocatalytic water purification process during daytime or with the use of UV rays.

Panasonic created a technique that binds the photocatalyst (titanium dioxide) to a commercially adsorbent and a catalyst known as zeolite, allowing for successful removal and purification of photocatalysts from reused water. Titanium dioxide can mineralize a variety of organic molecules, resulting in safe end products. To separate compounds, the catalyst employs UV sun’s energy or artificial light.

Organic substances, estrogens, insecticides, pigments, petroleum products, and microorganisms including viruses and chlorine-resistant bacteria, as well as inorganic substances like nitrous oxides, are all broken down employing photocatalysis.

Photocatalytic water treatment systems are appropriate for use in water and wastewater treatment plants and can treat industrial wastewater containing high levels of organic compounds or metals.

Aquaporin Inside Technology

Aquaporin Inside is a Danish cleantech company’s technology. Aquaporin is based on a biomimetic membrane architecture for water purification. Aquaporins are proteins that allow water to pass quickly and selectively across the cell membrane. They let the cell regulate its volume and internal osmotic pressure in response to changes in hydrostatic and osmotic pressure.

Aquaporin water treatment
The unique architecture of aquaporins facilitating fast water purification

The unique geometry of the aquaporin channel allows water molecules to flow through while blocking all other substances. The creation of artificial bio-mimetic membrane systems is also based on natural bio-mimetic membranes. The technique is employed in water filtering and purifying facilities in both industrial and residential settings.

Aquaporin Inside membranes are still the only membranes available in the market that cleanse water supply using aquaporins. The membranes are suitable for both forward and reverse osmosis (FO/RO) processes.

In conjunction with European and US-based enterprises, the Aquaporin Space Alliance (ASA), a joint venture between Aquaporian and Danish Aerospace Company (DAS), is monetizing the internally developed Aquaporin Inside technology in space applications and programmes.

Automatic Variable Filtration (AVF) Technology

AVF technology, or Automated Variable Filtration, is just an uncomplicated technique in which the upward flow of influent is cleaned by the downward flow of filter material. It removes the requirement for any further filter media cleaning method or freshwater.

typical two-stage AVF(automatic variable filtration)
working of two-staged AVF (automatic variable filtration) water treatment plant

The AVF approach uses a configurable array of continually cleaned descending bed filters. The system’s two-stage architecture includes two sets of material filters that may operate in serial or parallel mode.

The procedure produces water of comparable quality to microfiltration but at a fraction of the expense of low-pressure membranes. It has no moving components and uses less energy, resulting in lower running costs and maintenance expenses.

AVF systems are ideal for municipal drinking treating wastewater, as well as wastewater reuse and recycling membrane pre-filtration, and desalination.

Some of the key firms participating in the development of AVF technology-based goods and services are R2O water technologies, process research ORTECH (PRO), and Eureka Forbes.

Authored by Sumiti goel

Content Writer (Erakina by RTMN)

12 Nov 2021

Tags: water

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