Water pollution continues to be a major problem across the planet, especially in the Global South. Currently, water pollution or scarcity affects around 2.8 billion people across the globe, and is responsible for around 80 percent of all illnesses.
Causes for weather scarcity and pollution are many-fold. Warm weather has increasingly dried up reservoirs, while freshwater rivers are at historic lows. The growth of agriculture – vital to feed an expanding population – has also placed more stress on water supplies, while irresponsible industrial processes pollute those which are available.
One solution to these problems is to turn to traditionally non-drinkable sources of water, such as the three-quarters of the planet which are salt-water seas and oceans. The desalination of this water could potentially provide for the needs of growing communities across the world.
One Polish startup, Nanoseen, is working to develop a simple, but effective non-powered means of removing both salt and contaminants from water sources. Their method employs a series of ‘NanoseenX’ membranes containing regulated and controlled pores ranging in size from about 0.1 nanometres to 0.8 nanometres. These holes are large enough to allow through water, but small enough to capture salt and any contaminants.
Around 30 different types of membrane have been developed from a combination of many types of nanomaterials each. Each of the membranes has been developed with a specific function in mind, and can be combined with others for increased levels of purification.
These membranes are inserted into a vertical cylinder through which water is passed. Depending on the salinity of the water and/or its level of contamination, anywhere between two or twenty of these membranes will be required. Each membrane has been designed to remove different sizes of contaminants, from larger physical objects, to pesticides, heavy metals and eventually viruses and nanoplastics.
Each membrane is expected to last for around 200 days of 24 hour work, and can be ‘regenerated’ up to 10 times, either using pure water, solar energy or compressed air. Nanoseen claim their approach can filter up to 1000 litres a day, although they are working to boost this amount by up to ten-times
The advantage of the NanoseenX system is the simplicity of its approach. No electricity or power is needed, as gravity alone can move the water through the cylinder. This makes it ideal for off-grid or rural communities without electrification, with Nanoseen claiming it is the only current desalination system capable of doing so. The system is also relatively rapid, with water passing through it in only two to five minutes, and affordable. Membranes cost between 0.08 and 0.5 USD each, and Nanoseen suggest their system can produce one litre of drinkable water for only 0.0001 USD.
Nanoseen’s approach is only one effort to harness the power of desalination to produce drinking water. Virginia Tech University has developed an interesting, innovative system which replicates the natural process of mangrove trees to suck seawater up into a filtration system without the need of mechanical power. Membranes themselves could also be used to generate electricity via osmotic processes. In these systems, water is used to apply pressure above or below a membrane, ultimately creating energy. However, developing a reliable, cost effective osmotic system is still being explored.
In addition to desalination and purification, Nanoseen has also applied its experience with nanotechnology to other sectors. In addition to membranes, it has also produced NanoboosteX, a plant accelerant designed to reduce fertilisers, and NanopowderX, a powder used to degrade plastics from salt and freshwater.