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

Surwon Technology to sign filtration products deal

Hong Kong-based advanced materials company Surwon Technology announced that a version of a new membrane coating it has tested in heavy-duty desalination applications could soon be part of new water filtration products specially-developed for the consumer market.

The ultra-thin, graphene-based coating has reportedly continued to perform well in ongoing controlled tests at various desalination plants on the Chinese mainland and the company says it is convinced the technology can make a substantial contribution to reducing the cost of thermal and reverse osmosis systems.

Spanish scientists open the door to using graphene in smart filters and sensors

As part of a national research collaboration, Spanish researchers including the ICN2 have reached a milestone in graphene research, that potentially brings science a step closer to using graphene in filtration and sensing applications.

The researchers have successfully synthesized a graphene membrane with pores whose size, shape and density can be tuned with atomic precision at the nanoscale. Engineering pores at the nanoscale in graphene can change its fundamental properties. It becomes permeable or sieve-like, and this change alone, combined with graphene's intrinsic strength and small dimensions, points to its future use as the most resilient, energy-efficient and selective filter for extremely small substances including greenhouse gases, salts and biomolecules.

Graphene Supercapacitors Market Report

Indian team develops a graphene-based water cleaning process using seaweed

A team of Indian scientists has developed a graphene-based nano-material drawn from seaweed for effective treatment of toxic wastewater without using any chemicals.

Indian team develops graphene-based water cleaning process using seaweed image

Membrane-based filtration processes are generally used to treat industrial wastewater but can’t usually fully filter out heavy metal contaminants. In order to address this problem, processes that use activated carbon, graphene or carbon nano tubes are being developed as carbon-based processes can help remove dyes and heavy metals through adsorption. Researchers at the Central Salt and Marine Chemicals Research Institute, Bhavnagar, have developed a 'green' process by using seaweed as starting material. They have synthesized a graphene-iron sulfide nanocomposite from an abundant seaweed - Ulva fasciata – through direct pyrolysis technique.

Australian team develops new GO-based filter that can improve drinking water quality

Researchers at UNSW have developed a graphene-based, laboratory-scale filter that can remove more than 99% of the natural organic matter left behind during conventional treatment of drinking water. In a research collaboration with Sydney Water, the team has demonstrated the success of the approach in laboratory tests on filtered water from the Nepean Water Filtration Plant in western Sydney, and is working to scale up the new technology.

Australian team develops promising GO membranes for water treatment image

"Our advance is to use filters based on graphene – an extremely thin form of carbon. No other filtration method has come close to removing 99% of natural organic matter from water at low pressure," the UNSW team said. "Our results indicate that graphene-based membranes could be converted into an alternative new option that could in the future be retrofitted in conventional water treatment plants."

Ionic Industries provides updates on supercapacitor and water treatment work

Ionic Industries logoIonic Industries has provided updates on its research, commercial products and industry outreach. Among the mentioned highlights is the fact that Ionic is engaging with a number of companies to develop collaborations focused on its printed micro planar supercapacitors, named MICRENs. Also, on Ionic's other printed supercapacitor technology, the ORIGAMI Caps, the Company is working toward developing a prototype device for use in Internet of Things applications and is aiming to have a product to test in the next month.

On the Company's water treatment work, it was said that work with Clean TeQ and Monash under the CRC-P program continues apace. Much focus at this point is on upscaled manufacturing, ensuring the feasibility of manufacturing the membranes and graphene oxide (GO) sand products at industrial scales. The next major milestone that Ionic is aiming for is triggering the formation of a joint venture with Clean TeQ when the path to market (and revenues) for this technology will become much clearer.

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