A Knowledge Perspective
Any discussion on water purifying technologies should include Reverse Osmosis, popularly known as RO. But is RO purification required every time? Surprisingly, the answer is NO because RO purification has its disadvantages.
- RO water purification removes TDS but eliminates essential minerals like magnesium and calcium from the source water. So, the RO purified water tastes bland. Therefore, water purifier manufacturers use supplementary technologies such as TDS controllers, mineralizers, etc., to replenish the lost essential minerals.
- RO water purification is unnecessary if the TDS levels in the source water are less than 500ppm. However, it is advisable to go with RO purification if the source water has a high concentration of harmful contaminants like arsenic, lead, and antimony, even if the TDS levels are less than 500ppm. Secondly, RO water purification is better if the water sources are near industries, chemical factories, and polluted areas.
- RO water purification wastes precious water. While there are alternate uses for wasted water, it generally flows down the drain. Manufacturers like Kent have introduced Zero Water Wastage RO water purification. However, this technology is not feasible because it involves recirculating wasted water to the overhead tank. In addition, it can cause recontamination of source water.
So, if RO water purification is not always necessary, what alternatives are available for purifying drinking water?
Reverse Osmosis Alternatives – Are they?
Though RO does not have any perfect alternative, supplementary technologies are available.
Ultra Violet Purification
UV rays kill bacteria and viruses to provide hygienic and healthy drinking water. Hence UV purification is ideal when the water source does not contain industrial waste and the TDS levels are low. Please note that UV Purifiers cannot remove TDS from the water.
Ultra-Filtration
Usually, our municipalities use RO water purification on a large scale before supplying it to individual homes. Under such circumstances, the water can collect impurities on the way. Therefore, ultra-filtration should suffice to remove these more significant impurities.
Activated Carbon Filters
The source water can contain aromatic contaminants that can give a foul smell to it. Activated carbon filters strategically placed before and after the RO membrane removes these aromatic compounds and improves water taste.
Zero Water Wastage RO purification
Kent introduced this technology where the appliance recycles RO wastewater to the overhead tank. Hence, it increases water contamination and disadvantages consumers who do not have RO water purifiers in their homes. However, it is a viable technology if you live in an individual house with a dedicated overhead tank. You can use the wasted water for other purposes like watering plants, flushing toilets, etc. Otherwise, the technology is a gimmick.
Read: Kent Zero water wastage explained
Zinc and Copper Infused purification.
HUL Pureit and Aquaguard introduced Zinc and Copper-infused purification technology to enhance water purification. However, this technique is a marketing gimmick because the technology infuses copper and zinc ions into RO purified water. This technology does not filter water independently like UV and UF. Besides, mineralizers perform a similar job of enhancing water quality and taste.
Read: Do we really need copper and Zinc water purifiers
Latest Water Purification technologies – A global perspective
Generally, we know of RO, UV, UF, and other standard water purification technologies. However, futuristic technologies are available for purifying water.
Read: RO vs UV vs UF
Nanotechnology
Nanotechnology uses specific materials such as silver, copper, zero-valent iron particles, nano-membranes, nano-adsorbents, and nanostructured photocatalysts in the atomic and molecular state to purify water.
Nanoparticles have a large surface-to-volume ratio to enhance the adsorption of chemical and biological particles while eliminating metallic pollutants and separating contaminants at low concentrations.
Ideally, carbon nanotubes are the best nanomaterials used in water purification. They can remove biological, organic, and inorganic contaminants from water. Besides, they enhance the water’s taste. The technology is somewhat similar to using activated carbon particles for purifying water. The difference is in particle size.
This technology is new to India. Tata has unveiled a new model, Swach, that uses nanotechnology for water purification. The Swach model uses Rice Husk Ash with nano silver particles to purify water.
RHA contains activated silica and carbon to reduce water turbidity and remove organic impurities. This technology eliminates pesticides and other microbial contaminants.
However, this technology cannot remove heavy contaminants like lead, arsenic, nitrates, sodium, lithium, and compounds like ammonia and strong acids/bases. But, Swach water purifiers comply with US EPA standards. So, these products cannot replace RO water purifiers but supplement their purification.
Other nanotechnology applications include carbon nanotubes, golden nanoparticles, and nanocellulose applications.
Acoustic nanotube technology
NASA has developed a unique water purifying technology that uses sound instead of pressure to propel water through small-diameter carbon nanotubes. Acoustic nanotube technology comprises an acoustically driven molecular screen with carbon nanotubes to block large molecules and contaminants while allowing passage of pure water.
This technology is different from Reverse Osmosis because it drives water away from the pollutants instead of removing the contaminants. Hence, flushing out wastewater is unnecessary. As a result, this process consumes less power.
Though this technology is not available for domestic water purification, it is widely used in commercial establishments, wastewater treatment plants, desalination units, laboratories, distilleries, municipal water purification plants, etc.
Photocatalytic water purification technology
Photocatalytic water purification is similar to UV purification technology because it uses ultraviolet rays to remove toxic substances from water. Panasonic has developed this unique technology that binds a photocatalyst, titanium dioxide, to a commercial adsorbent and zeolite to remove impurities from the water. Simultaneously, it also recovers the photocatalyst for reuse. Photocatalysts are helpful in mineralizing organic substances into safe end products. The catalysts use UV radiation from sunlight and artificial light to purify water.
Besides breaking down organic compounds like pesticides, crude oil residue, dyes, estrogens, and microbes, this water purification technology can disintegrate inorganic compounds like nitrous oxide. Hence, this technology is helpful in large-scale water purification like wastewater treatment facilities and industrial applications.
Using sunlight to purify water is not new to India. Our scriptures mention this water purification technology used by Indians for ages. Jiva, an indigenously Indian water purification enterprise, uses this technology to produce low-cost water purifying devices. The company has named these products Jiva Yami and Jiva Vipasa for domestic use and Vipasa, Jahanvi, and Dihanga for farm use.
Aquaporin Inside technology
Aquaporin, a Danish enterprise, has patented a unique water purification technique known as Aquaporin Inside Technology that uses a bio-mimetic water treatment membrane design. This technology enables selective water transfer across the cell membrane by blocking contaminants.
This technology is presently unavailable in India but is used widely across the US and Europe in industrial and household water purification systems. It combines Forward Osmosis (FO) and Reverse Osmosis (RO) techniques to purify water.
The Aquaporin Space Alliance uses this patented technology in space applications and programs.
Automatic Variable Filtration (AVF) technology
Municipal water purification and wastewater treatment plants use Automatic Variable Filtration technology to purify water on a large scale. This water treatment technology works on the principle of cleaning the upward influent flow by a downward flow of filter media. Therefore, it eliminates the need for additional water purification processes.
This water purification method uses multiple bed filters in descending order in a variable array, either in serial or parallel mode. This technology does not involve moving parts and is the most cost-efficient micro filtration technique. Hence, it reduces operational and maintenance costs, making it ideal for use in municipal water, desalination, and wastewater treatment plants.
R2O Water Technologies, Eureka Forbes, and Process Research ORTECH are prominent companies that develop AVF technology-based products.
Innovative water purifying technology – Portable water purifiers
Lamaara Technologies, a Kerala-based start-up company, has introduced a ground-breaking water purifying solution, Aquabot, accessible by millions comfortably. Aquabot is a portable and collapsible water purification bottle that people can use to refine almost any water source while traveling.
It does not need external power sources like electricity for its functioning. Besides, the bottle is reusable and eco-friendly. One cartridge can purify up to 1000 liters of water. Hence, it is a cost-efficient device. Moreover, this product can filter tap water and make it safe for human consumption.
The company has expanded its product pool by launching Waterfall, a household water purifying solution. This water purifier does not use any power, lasts longer, and does not waste any water like RO water purifiers. In addition, the company plans to launch water ATMs across the country, where people can conveniently access purified water at low costs.
Final Thoughts
RO water purifying technology is suitable for eliminating TDS but removes essential minerals from water. Besides, it wastes water. Secondly, the RO water purifier manufacturing cartel aggressively markets its products and recommends RO purification, even when it is not necessary. Hence, one needs to look beyond RO water purification. We have discussed various technical innovations that purify water and make it suitable for human consumption.
Sources
https://www.sciencedirect.com/topics/materials-science/photocatalysts
https://news.panasonic.com/global/stories/699
https://www.nasa.gov/centers/johnson/techtransfer/technology/MSC-24180-1_Water-Filtering-Device.html