The world over, there are eight common water treatment technologies for treating potable water for domestic use and consumption. Each technology has its own advantages and disadvantages.

• Filtration
  • Uses ceramic yarn wound cellulose carbon candles
  • Provides clean water
  • Water not safe to drink
  • Turns into a breeding ground for bacteria
• Boiling
  • Kills water-borne pathogenic microbes
  • Killing action - Protein denaturation
  • Damages cell wall of microbes
  • Spores are not killed
  • Cannot remove organic impurities
  • Greater chance of recontamination
  • Flat taste due to loss of dissolved oxygen
  • Alters the mineral content
• Chlorination
  • The process of treating water with liquid Chlorine,Chlorine gas,Sodium Hypochlorite or Bleaching powder
  • Kills a part of the microbial load
  • Cheap method of purification
  • Used in public water supply
  • Affects the cell wall enzymes to destroy the cell
  • Requires a contact time of 1 hour for action
  • Risk of over dosing
  • Slightly changes the pH of the water
  • Increases corrosive property of the water
  • Leaves taste and smell in the water
• Iodination
  • Ion-exchange resins are treated with Iodine. hen water passes through this, the resin releases Iodine/ Iodide into the water which inactivates the bacteria
  • Killing action - denaturating metabolic products such as protein and enzymes
  • Requires contact time of 10 seconds
  • Better killing effect than chlorination
  • Costlier than Chlorination
  • Leads to health hazards if the limit of 2 mg/day is exceeded on a long term
• Ozonization
  • Ozone is a 3 atom combination of Oxygen produced by passing dry Oxygen through an electrical discharge (2000-5000 V)
  • Powerful disinfectant
  • 12.5 times more suluble in water than Oxygen
  • Requires contact time of 3 - 5 minutes
  • Ozone smells in the treated water
  • Any leakage of Ozone affects the mucous membrane of nose, eyes and lungs (above 0/05 ppm)
  • Unstable. Must be generated on site only
  • Less production in presence of Chlorine
• Reverse Osmosis (RO)
  • As a process, osmosis has been in existence since the beginning of the universe and occurs in cells of living organisms.
  • It is a process by which the natural movement of the solvent molecules from a region of lower to higher solute concentration takes place through a partially permeable membrane until a state of equilibrium is reached on both sides of the membrane.
  • When this process is reversed, it is called Reverse Osmosis.
  • In other words, reverse osmosis is when solvent molecules move from a region of higher to lower solute concentration across a permeable membrane until a state of equilibrium is reached on both sides.
  • Accordingly, the osmotic pressure is defined as the pressure required in maintaining equilibrium, with no net movement of solvent across the membrane.
  • In water treatment technique, the phenomenon of Reverse Osmosis (RO) is employed to remove dissolved salts in water using a synthetic membrane for filtration. However, this not only removes insoluble particles but also molecules and ions. Further, the concentration of ions near the membrane leads to ‘polarization’ which results in an increase in the osmotic pressure of the solution to be treated, sometimes followed by precipitation. The continuing flow of input water under high pressure (>200 psi) flushes the membrane thereby removing the ion concentrations and/or precipitates.
  • RO systems are not normally "water efficient" or “environment-friendly” as there is a significant wastage of water. Purchase and installation costs can also be significant. Further, RO membrane is notoriously prone to bacterial build-up and ruptures. Slime-forming bacteria can cause rapid deterioration of performance.
  • Due to these factors, a major membrane manufacturer has the following warning printed in red letters on the packaging: "Do not rely on this membrane for Cryptosporidium or Giardia cyst removal".
  • -- RO water lacks minerals and oxygen, hence the "flat", "stale" taste when used for drinking.
  • -- Uses a high pressure membrane process
  • -- Separates low molecular weight compounds from water
  • -- Reverse Osmosis uses smaller pores (0.0001 micron)
  • -- Capable of removing salts, bacteria, protozoa, cysts and viruses
• Ultra Violet (UV) treatment
  • Ultra Violet is ultraviolet light waves on the electromagnetic spectrum that are similar to the light from the sun.
  • Ultraviolet light waves are in use for decades in different technologies including radiation, x-rays and water filtration.
  • In water filtration, it is accepted as an effective method of water treatment as it reduces harmful bacteria, chemicals and microbes present in the water.
  • Although UV rays are present in sunrays, the rays used in water filtration are of shorter wavelengths than those used in x-rays and exposure to it is not harmful.
  • Ultra Violet systems (UV) expose the water to intense ultraviolet radiation, which kills pathogenic bacteria (cholera, typhoid, dysentery, etc.) and viruses. However, it is not effective against cysts.
  • Since UV is not a physical filter, suspended particles (or turbidity) in the water could “shade or shield” the bacteria from direct ultra violet rays of the source thereby allowing “live” bacteria and viruses to pass through the system. Thus, a good UV systems comes with ceramic cartridge for a pre and post radiation filter.
  • The following factors can reduce the UV performance:
  • -- Fouling due to buildup of iron and hardness on the quartz sleeve
  • -- Deposition of iron, decayed organic matters, tannins and any UV energy absorptive material commonly found in tap water
  • UV alone neither removes any particulate matter or turbidity nor does it remove volatile organic compounds such as pesticides or insecticides.
  • In order to ensure the efficacy of UV water filtration systems, the ultra violet bulbs need to be replaced annually. The electricity consumption is low. UV is often combined with carbon filtration and other technologies to further enhance removal of bacteria and other waterborne contaminants.
  • When deciding on ultra violet filter for water filtration, purchase, installation, operating and maintenance costs need to be taken into account
  • -- UV filtration rays are of shorter wavelength than sunrays and hence not harmful
  • -- Accepted as an effective method of water treatment
  • -- Exposes the water to intense ultraviolet radiation, which kills pathogenic bacteria (cholera, typhoid, dysentery, etc.) and viruses. However, it is not effective against cysts
  • -- Since UV is not a physical filter, suspended particles (or turbidity) in the water could “shade or shield” the bacteria from direct ultra violet rays of the source thereby allowing “live” bacteria and viruses to pass through the system. Thus, a good UV systems comes with ceramic cartridge for a pre and post radiation filter
  • -- Fouling due to build-up of iron and hardness on the quartz sleeve
  • Deposition of iron, decayed organic matters, tannins and any UV energy absorptive material commonly found in tap water
  • -- UV alone neither removes any particulate matter or turbidity nor does it remove volatile organic compounds such as pesticides or insecticides.
  • -- The ultra violet bulbs need to be replaced annually. The electricity consumption is low
  • -- Often combined with carbon filtration and other technologies to further enhance removal of bacteria and other waterborne contaminants
  • -- Purchase, installation, operating and maintenance costs need to be taken into account
• Membrane Technology
  • Ultra Filtration (UF) is a type of membrane filtration technique which employs a semi permeable membrane consisting of a thin layer of material that is capable of separating substances when a driving force is applied across it.
  • Ultra Filtration was earlier limited only to desalination but is now increasingly used in removal of microorganisms, particulate and natural organic material, which impart color, tastes, and odors to the water and react with disinfectants to form disinfection byproducts.
  • With advancements made in membrane production and module design, capital and operating costs continue to decline.
  • In ultra filtration, the water flows either inside the shell or in the lumen of the hollow fibers of the membrane material thereby retaining the suspended solids and solutes of high molecular weight and allowing water and low molecular weight solutes to pass through the membrane.
  • Ultrafiltration differs from reverse osmosis, microfiltration or nanofiltration in terms of the size of the molecules retained.
  • Ultra filtration needs to be strategically combined with other purification technologies to qualify as a complete water treatment system. UF is ideal in removing macromolecules like proteins, bacteria, pyrogens, etc. that are larger than the membrane pore size from water.
  • UF can either be used as pretreatment for reverse osmosis systems or as a final filtration stage for deionized water.
  • The UF membrane system scores over conventional filtration and disinfection processes since it:
  • -- does not require chemicals (coagulants, flocculates, disinfectants, pH adjusters)
  • -- is based on size-exclusion as against media depth filtration
  • -- provides good and constant quality of the treated water through removal of particle and microorganisms
  • -- has process and plant compactness
  • -- uses simple automation
  • -- Uses a low pressure membrane process
  • -- Separates high molecular weight compounds from water
  • -- Ultra-filtration has large pores (0.01 microns) than reverse osmosis
  • -- Capable of removing bacteria, protozoa, cysts and viruses

Max Aqua Limited manufactures water purifiers and dispensers that employ three types of scientific water treatment technologies and their combinations.

• Reverse Osmosis (RO) Technology
• Ultra Violet (UV) Technology
• Ultra Filtration (UF) Technology