Water filtration is a vital element in the provision of potable water. We are fortunate in the UK to have some of the cleanest potable water in the world.
For water to become clean enough for us to drink, any impurities must first be removed. This is achieved by passing the water through various filters, before sterilising it to kill harmful microbes. After that water has been abstracted from groundwater sources, rivers or lakes, it is filtered through rapid gravity filters - tanks of coarse sand which trap larger particles. The water is then filtered through slow sand filters, which are beds of finer sand, and this removes additional particles still in the water. The final stage is to treat the water with ozone, carbon or ion exchange to ensure the removal of fine particles and microbes.
In recent years, engineers and scientists around the world have been working on ways of improving the filtration process to make potable water cheaper and more plentiful. Here we take a look at some of the most exciting new developments.
A team of engineers and scientists at the University of Manchester has been developing revolutionary water filtration technology that will make the filtration process greener and cheaper than the systems currently available. The team has just been awarded half a million pounds in funding that will allow them to scale up the research and development of the new filtration system.
The new development is an energy-efficient and versatile membrane coating. It is based on a material called modified molybdenum disulphide (MoS2), which has similar qualities to graphene (which was also developed at the University of Manchester). As the world’s first 2D material, graphene is only one atom thick, but it is 200 times stronger than steel and is extraordinarily flexible. MoS2 is set to revolutionise the water purification process as the nanofiltration membranes are ultra-high performance and corrosion resistant.
Richard Lydon, a leading filtration expert who has been working on the project, said the new filters are “robust in any environment and can be tailored to reject target particulates such as nitrates, phosphates, PFAS/PFOS, dissolved organics, heavy metals and other pollutants, offering unique selling points to meet the needs of the water industry.”
In 2021, Ofwat launched a £200 million Innovation Fund that awards grants to research bodies working on innovative technologies that will help improve and accelerate solutions to the provision of clean water, including tackling issues such as leaks, pollution and water quality. Previous winners have been working on a variety of projects to improve water quality. These include a project looking at alternative ways of removing phosphorus from rural wastewater treatments, a project that has identified a naturally occurring bacteria that can remove ammonia from water without producing greenhouse gas emissions, and a project that is developing genetic sequencing to determine all the bacterial species in water to help improve the speed and accuracy of water quality investigations.
Organisations and businesses around the world are also looking for innovative ways to improve water treatment.
One project in the US has gone back to nature with the use of moss as a sustainable plant-based water treatment solution for water towers. It is a low-cost solution that is easy to install, and it will also prevent corrosion and scaling in the tanks themselves. When used with the correct biocide, it can even keep water towers free from legionella, the bacteria that can cause the potentially fatal Legionnaires’ disease.
In Australia, engineers are developing Automatic Variable Filtration (AVF) technology where water is introduced to the bottom of the filtration bed and moves upwards. AVF uses environmentally friendly technology, is self-cleaning, and uses less power and less compressed air than conventional filtration. The AVF filtration media has been engineered to last a lifetime, whereas in conventional filtration systems, it needs to be replaced every 2-3 years.
In Poland, engineers have developed NanoseenX, a series of nanomembranes made from a combination of nanomaterials that trap impurities and salts. The system uses gravity to pass the water through the filters, eliminating the need to use additional energy.
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