Food & Beverage News: F&B Specials - Water purification methods: stay healthy, drink pure

There is almost nothing that we can do without water, especially at home. Apart from quenching thirst, water is needed for cooking, cleaning, watering plants, as an additive to dilute substances -- the list is endless. Many people don't consider the purity of the water we cook food with or the water we shower or bathe in. Significantly, when a person showers, the water opens up the pores of the skin and water penetrates into it. Pure water is very beneficial for the skin and hydrates it. If somebody suffers from dryness or any skin disorder, it's even more important to bathe in clean water.

Unfortunately, the quality of water supply leaves a lot to be desired. Water-borne diseases are a major cause for concern, especially among children, more so in the developing world where clean potable water is scarce. This problem is getting accentuated with depletion of water resources, global warming, unprecedented growth of cities and pressures of globalisation and commercialisation of water supply. So much so that some studies have shown that there are over 2,100 toxins in our drinking water.

As prevention is better than cure, households have to ensure that the water supplied to them is properly treated and disinfected before it is used. Municipal purified water is not completely safe, as it does not kill viruses and there is also a danger of sewage contamination through leaky pipes, whereas bottled water is too ex pensive. Most households in urban centres have woken up to the need for treating or purifying water to keep diseases at bay but the situation still remains dismal in rural areas.

Boiling
The most common, traditional and simple method used by millions across the world is disinfection by boiling. Boiling can eliminate all bacteria and virus but it must be done correctly. Water needs to be roll boiled, that is boiled for at least 20 minutes after reaching the boiling point till the water rattles and then preserved in a clean container preferably with a narrow mouth. This stored water should be used for drinking only by pouring the water out. No smaller utensils should be introduced inside the vessel in which the boiled water has been stored so that no disease causing organism is introduced into it - the benefits of boiling are then reduced to naught.

Candle water filters
Another easy method of ensuring safer water is by the use of storage candle home filters. These ceramic filters need to be boiled and scrubbed so that there is effective filtration, else they become breeding ground for bacteria. The candles need to be replaced when the filtration becomes ineffective. There are also filters that can be fixed on taps to clean running water at source. Tap attachment filters also need to be cleaned regularly. Unfortunately, most tap filters trap only large impurities. Bacteria can slip through small pores and generally such a method of filtration is not very effective

Multi-stage purification
Even the next level storage purifiers with multi stage purification are affordable water purification solutions. They operate without electricity, are easy to operate, low on maintenance, and don't need running water to operate. They look like traditional water filters, fitted with purification cartridge with multi-stage purification - pre-filter purification, activated carbon purification, bacteria disinfectant and water polisher/taste improver.

Chlorination
On a larger scale, disinfection of drinking water by chlorination is one of the most effective methods to render the water safe from the hygiene viewpoint, which also improves the water quality by controlling colour and odour, organic matter and plankton, etc. One of the oldest methods, chlorination is being used since the year 1900 due to its high inactivation efficiency towards a broad spectrum of micro-organisms, economy, maintenance costs, etc. Despite advancements in science, chlorine is still regarded as the most effective disinfectant. It has a very broad spectrum of disinfections against bacteria, viruses, and other harmful pathogens. Chlorine is generally used to disinfect municipal water for public supply, hospitals, railways, swimming pools, etc.

Halogen tablets
For filtering water during emergency situations and where there is risk of contamination, Halogen tablets are avail able. These tablets can be dissolved in water (the amount of water for which these tablets will be effective varies from one brand to another and as such the instructions should be looked for in the packages). Bleaching powder can also be dissolved in appropriate quantities based on the quantity of water so that the source of the drinking water can be decontaminated.

Ultrafiltration
Ultrafiltration removes solids, bacteria and viruses by forcing the water to pass through a semi-permeable membrane which does not allow the particulates to pass through but does allow the flow of the water. The flow of the water also constantly cleans off the membrane of the particulates it catches. Such purifiers are useful for areas with irregular electricity supply, as they work without electricity. They require low maintenance and the life span of their purification membranes is long. Such systems are usually used in large water treatment plants; its presence in domestic water purification is limited but they are fast gaining acceptance as household water purifiers.

De-ionisation systems
De-ionisation systems consist of wall-mounted, plumbing-connected cylindrical cartridges in home with a sink or tub. In such systems, hydrogen ions are exchanged for metallic ions in the water supply and then this treated water passes through a second set of cylinders. Now an anion exchange material consisting of replaceable hydroxyl anions and fixed irreplaceable cations makes the water non-acidic and fit for consumption. These systems are among the cheapest but they require much cleaning.

E-boiling Systems
Electronic water purifiers do a convenient and complete job of water purification. However, they need regular and periodic maintenance and should be from a reliable manufacture which can provide support and service back-up. E-boiling ensures that every drop of water is as pure and as safe as water boiled for 20 minutes. Also it removes all physical impurities like dust, dirt and organic impurities like chlorine.

PAC Treatment
Powdered activated carbon treatment (PAC) uses the sprinkling of 'water hating' but 'oil loving' carbon powders (different formulations filter out different things) to let the various unwanted substances get 'captured' by the oily surface layer while the clean water flows on underneath the oil and to the tap.

Reverse Osmosis Systems
The water purification systems most in demand right now are the ones which use 'reverse osmosis' or RO technique. The reverse osmosis water purification process works like ultrafiltration but is designed to remove a different and greater range of things from the water, such as excess chlorine, dirt, and the 'hard water' elements These systems do a very efficient good job of removing almost all known dissolved contaminants from water through the use of a semi-permeable membrane. It involves the reversal of flow, through a membrane form a high salinity solution to high purity, or permeate stream on the opposite side of the membrane. Pressure is used as the driving force for the separation. This means that through the reversal flow, RO not only removes the impurities, it also desalinises the water. It also removes potentially dangerous heavy metals such as lead, chromium, copper, cadmium, etc. On the flipside, it also removes the beneficial minerals that are vital for our health such as calcium, magnesium, potassium, etc. and nowhere on earth does de-mineralised water appear naturally. RO systems are best suited for places which get water from a ground source or get a supply of hard water.

UV radiation Systems
Another method is through the use of UV radiation. UV rays are emitted in the unit by a lamp in measured quantities. The UV radiation rearranges the DNA of viruses and bacteria and renders them incapable of reproduction, which is essentially death for them, making them harmless to humans. This method does not add anything to the water, nor does it remove any minerals from it. UV purifiers usually come with three-four purification stages viz, a sediment filter (pre filter) and an activated carbon cartridge. Such purifiers are most suited for municipal tap water and give protection from disease-causing bacteria and viruses but do not alter the level of dissolved solids.

Although there are numerous techniques for water purification, a complete water purification process is one which will remove a host of things including algae, suspended particles of organic material, dissolved solids, bacteria, viruses, fungi, minerals and heavy metals. Each technique has its pros and cons and the technology best suited for the job should be chosen based on factors like the source and the quality of the water supply.