What is water treatment?

Water treatment is the collective name for a group of mainly industrial processes that make water more suitable for its application, which may be drinking, medical use, industrial use and more. A water treatment process is designed to remove or reduce existing water contaminants to the point where water reaches a level that is fit for use. Specific processes are tailored according to intended use - for example, treatment of greywater (from bath, dishwasher etc.) will require different measures than black water (from toilets) treatment.

Water treatment photo

Main types of water treatments

All water treatments involve the removal of solids (usually by filtration and sedimentation), bacteria, algae and inorganic compounds. Used water can be converted into environmentally acceptable water, or even drinking water through various treatments.

Water treatments roughly divide into industrial and domestic/municipal. Industrial water treatments include boiler water treatment (removal or chemical modification of substances that are damaging to boilers), cooling water treatment (minimization of damage to industrial cooling towers) and wastewater treatment (both from industrial use and sewage). Wastewater treatment is the process that removes most of the contaminants from wastewater or sewage, producing a liquid that can be disposed to the natural environment and a sludge (semi-solid waste).

Wastewater treatments usually consist of three levels: a primary (mechanical) level, in which about 50-60% of the solids are removed from raw sewage by screening and sedimentation, a secondary (biological) treatment level in which dissolved organic matter that escaped primary treatment is removed by microbes that consume it as food and convert it into carbon dioxide, water and energy. The tertiary treatment removes any impurities that are left, producing an effluent of almost drinking-water quality. Disinfection, typically with chlorine, can sometimes be an additional step before discharge of the effluent. It is not always done due to the high price of chlorine, as well as concern over health effects of chlorine residuals.

Seawater desalination are processes that extract salt from saline water, to produce fresh water suitable for drinking or irrigation. While this technology is in use and also holds much promise for growing in the future, it is still expensive, with reverse osmosis technology consuming a vast amount of energy (the desalination core process is based on reverse osmosis membrane technology).



What is graphene?

Graphene is a two dimensional mesh of carbon atoms arranged in the form of a honeycomb lattice. It has earned the title “miracle material” thanks to a startlingly large collection of incredible attributes - this thin, one atom thick substance (it is so thin in fact, that you’ll need to stack around three million layers of it to make a 1mm thick sheet!) is the lightest, strongest, thinnest, best heat-and-electricity conducting material ever discovered, and the list does not end there. Graphene is the subject of relentless research and is thought to be able to revolutionize whole industries, as researchers work on many different kinds of graphene-based materials, each one with unique qualities and designation.

Graphene and water treatment

Water is an invaluable resource and the intelligent use and maintenance of water supplies is one of the most important and crucial challenges that stand before mankind. New technologies are constantly being sought to lower the cost and footprint of processes that make use of water resources, as potable water (as well as water for agriculture and industry) are always in desperate demand. Much research is focused on graphene for different water treatment uses, and nanotechnology also has great potential for elimination of bacteria and other contaminants.

GO water permeability image

Among graphene’s host of remarkable traits, its hydrophobia is probably one of the traits most useful for water treatment. Graphene naturally repels water, but when narrow pores are made in it, rapid water permeation is allowed. This sparked ideas regarding the use of graphene for water filtration and desalination, especially once the technology for making these micro-pores has been achieved. Graphene sheets (perforated with miniature holes) are studied as a method of water filtration, because they are able to let water molecules pass but block the passage of contaminants and substances. Graphene’s small weight and size can contribute to making a lightweight, energy-efficient and environmentally friendly generation of water filters and desalinators.

It has been discovered that thin membranes made from graphene oxide are impermeable to all gases and vapors, besides water, and further research revealed that an accurate mesh can be made to allow ultrafast separation of atomic species that are very similar in size - enabling super-efficient filtering. This opens the door to the possibility of using seawater as a drinking water resource, in a fast and relatively simple way.

Further reading

Latest Graphene Water Treatment news

Researchers develop a technique to fabricate large squares of graphene riddled with controlled holes

Researchers at MIT have found a way to directly “pinprick” microscopic holes into graphene as the material is grown in the lab. Using this technique, they have fabricated relatively large sheets of graphene (roughly the size of a postage stamp), with pores that could make filtering certain molecules out of solutions vastly more efficient.

Holes would typically be considered unwanted defects, but the MIT team has found that certain defects in graphene can be an advantage in fields such as dialysis. Typically, much thicker polymer membranes are used in laboratories to filter out specific molecules from solution, such as proteins, amino acids, chemicals, and salts. If it could be tailored with selectively-sized pores that let through certain molecules but not others, graphene could substantially improve separation membrane technology.

Ionic Industries and Clean TeQ form a JV focused on graphene-based water treatment

Ionic Industries logoClean TeQ and Ionic Industries have formed a Joint Venture to progress the commercialization of graphene-based water treatment technologies.

The Companies stated that move follows the last 18 months in which Clean TeQ and Ionic have undertaken an extensive program of work together with Monash University to develop, manufacture and apply graphene oxide membranes for water filtration applications.

The Graphene Handbook

Grafoid and Liquinex to collaborate on water purification solutions using MESOGRAF graphene-based filtration technology

Grafoid logoGrafoid has announced a strategic partnership with Liquinex, a company specializing in waste water engineering needs, to provide commercial scale water treatment solutions using Grafoid’s MESOGRAF graphene-based filtration technology.

The graphene-based filtration products are said to be readily scalable to meet the rising commercial demands making them ideal for industrial level, niche applications such as the concentration of beverages, treatment of crude oil/water mixtures, biofuel and industrial wastewater treatments where reverse osmosis (RO) is not suitable due to the fouling tendencies when concentrated liquids are purged through RO cartridges.

NIST team brings nanofluidics computing closer to reality

Computers based on fluids instead of silicon is not a new concept, and now researchers at the National Institute of Standards and Technology (NIST) have shown how computational logic operations could be performed in a liquid medium by simulating the trapping of ions (charged atoms) in graphene floating in saline solution. The scheme might also be used in applications such as water filtration, energy storage or sensor technology.

Researchers simulate simple logic for nanofluidic computing image

NIST's ion-based transistor and logic operations are simpler in concept than earlier proposals. The new simulations show that a special film immersed in liquid can act like a solid silicon-based semiconductor. For example, the material can act like a transistor, the switch that carries out digital logic operations in a computer. The film can be switched on and off by tuning voltage levels like those induced by salt concentrations in biological systems.

Chinese team develops a material that purifies water with light

Scientists at the Academy of Sciences of China have created a new material that can purify contaminated water by means of light and a material made of networks of graphene and titanium dioxide.

The Chinese team stated that the graphene “catches the dirt” and the titanium acts as the photocatalyst and accelerates the process of photochemical degradation of toxic organic substances. The new material reduces the concentration of heavy metals, and can be effectively used for the treatment of industrial effluents. The new model was successfully tested in Shanghai and the provinces Jiangsu and Anhui.

XFNANO: Graphene and graphene-like materials since 2009 XFNANO: Graphene and graphene-like materials since 2009