Synergies in Water Conservation & Purity

Parag Kulkarni, Managing Director, A. O. Smith India Water Products As per syndicated reports India has around 4 percent of our world’s renewable water resources and is home to about 18 percent of the world’s population. Also it has nearly 20 river basins and receives an average precipitation of approximately 4,000 billion cubic meters annually. The annual ground water draft is 245 billion cubic metre which accounts for around 62 percent of the net water available. However the paradox lies here that despite having such an abundant water resource, 63 million Indians do not have access to clean potable water, majority being from the rural areas.It is estimated by the World Bank that 21 percent of communicable diseases in our country stem from unhygienic practices and unsafe water. Substantiating to this is the grim reality that a huge number of lives are claimed by water-borne diseases such as cholera, diarrhea or dysentery every year, from India.

As per the strategic plan 2011- 2022, by the Government of India, the goal is to provide 90 percent rural households with piped water whereas 80 percent of rural households with household taps by 2022. Yet, the primary challenge faced is the deteriorating quality of water owing to contaminants, for instance physical impurities (dust, sand, and hair), microbiological elements (bacteria, virus, protozoa and parasites), dissolved inorganics (salt, minerals, heavy metals like fluoride and arsenic) chemicals (pesticides, petro byproducts and toxins) and biological wastes.

Therefore, intense purification of water before drinking is the need of the hour and technological innovation has fairly eased up thisprocedure. Different purifiers use different methods to cleanse water from contaminants, having their own sets of pros and cons. Few such ways are discussed below.

• Sediment Filtration: In this process, cartridge sediment filters help in the removal of suspended particles such as clay, silt, sand or other organic matter. Untreated water is flown through a filter that traps suspended matter on the surface or that, which is present within the filter.

• Gravity: Through the simple technology of creating difference in pressure, water flows from higher chamber to lower chamber with installed filters to segregate dust particles and other suspended particles. The products are non-electric and mostly use some form of chemical for microbiological reduction (to kill bacteria, virus).
• Ultra Violet: In these kinds of purifiers, water moves through UV Radiations that ridswater of viruses, bacteria or other germs causing diseases like typhoid, cholera and dysentery. One advantage of UV is that its non-chemical based.

• Reverse Osmosis: Reverse Osmosis (RO) technology has been employed for years to purify drinking water and desalinate seawater for various domestic and industrial uses. Water is passed through a semi-permeable membrane under high pressure to separate dissolved solids present in it. The water molecules pass through the micro pores in the membrane; while other molecules cannot, there by yielding a purified water stream (permeate). Larger molecules are retained by the membrane as well as a portion of the water that does not pass through the membrane (concentrate or RO reject).

The future lies in the technology that not only purifies water but minimizes its wastage; a technology that fights against water scarcity

Although Reverse Osmosis is the most preferred technology out of all for the purification of water, yet one major drawback is that it wastes significant amount of water. There are few RO systems that assert to be zero waste, yet their processes are not devoid of absolute water wastage. Never-the-less they do meet the "zero waste" title by installing an electric pump to do something with the otherwise wasted water like circulating it back into the system.However this process also consequentially wears down the filter components fast. Another way is by pushing that concentrated water waste into the hot water line in a way that it ends up in your hands or your dish washer when you use the hot water.

Another method that can get higher water from a RO purifier is through control of the scales on the RO membranes and its components. The amount of water that comes out from the RO purifier compared to the inlet water is called Recovery rate of an RO which primarily depends on the feed water chemistry. Natural well water contains various concentrations of ions such as calcium, magnesium, fluorides and sulfates besides other low solubility compounds such as silica.The reverse osmosis process will concentrate these compounds in the concentrate (brine or reject) stream where their concentrations may exceed their solubility limits, there by causing precipitation.

The highest concentration of salts exist close to the surface of the membrane (due to an effect called polarization) where concentration may be 20% higher than the amount present in the bulk solution of the brine channel. This leads to the growth of crystals, which can form a scale on the surface of the membrane. A scaled membrane will show a high differential pressure, reduced permeate flow and poor quality permeate. To achieve higher recovery rates without scaling, it is necessary to pre-treat the raw feed water by injecting scale inhibitors or other chemicals. With scientific improvement in RO and the design innovation in flow management, it’s possible to minimize water wastage.

Water being a scarce yet indispensable life-sustaining resource, conservation is imperative. Water crisis is an increasingly alarming issue plaguing our modern world and UN predictions declare that by 2025, 1.8 billion people would be confronted with “absolute water scarcity”. Therefore, it is apt that many are rejecting conventional water practices and instead going for innovative solutions in order to secure future supplies of water for generations to come.

We live in an era where droughts drive farmers to misery and an all-day water supply is considered to be a privilege for few. Hence, the future lies in the technology that not only purifies water but minimizes its wastage, a technology that fights against water scarcity. After all, every drop of water is precious, every drop counts.