Frequently Asked Questions

FAQ's on UV water purifiers 9 questions
  • What problems does hard water cause?

    Scale formation on the inside of pipes, water heaters, showers are causing choking of pipes, loss of energy in heaters and clogging of showers.

    In cooking hard water spoils the taste and needs more time to cook. Washing of clothes requires more soap.

    Hard water leaves white stains on the vessels. It causes discomfort on skin and hair on bathing.

  • What are the differences in the technologies used for treating drinking water?

    Distillation, reverse osmosis, ultrafiltration, ultra violet light, ozonation and filtration are among the most common water treatment technologies. Robinson India highly recommends a water purifier that performs against all classes of contaminants, including microbiological, organic, inorganic, and pesticide contaminants.

  • What are the benefits of combining multiple technologies ?

    Using a hybrid or combination of technologies versus a single technology enables water treatment systems to address a wider range of contaminants than if they were to use one technology alone. A revolutionary 3-multi stage treatment process combining filtration, disinfection and adsorption guarantees better tasting and 100 % safe drinking water.

  • What are different stages of UV Purifier?

    UV purifier has following stages of purification :-

    • Sediment filtration
    • Activated carbon filtration
    • UV purification
    • Electrolytic sanitization

  • What are the drawbacks of conventional UV purifiers?

    UV purifiers only deactivate or paralyze disease causing microbes by altering genetic structure of cell and rendering them incapable of production. A lacuna of this technology is that some strains of paralyzed microbes may get reactivated or revived when exposed to direct sunlight.

    In conventional UV purifiers even the purest UV purified water that is stored in bottles or in containers can get re contaminated due to build up of slime or bacterial growth. This is a non remedial situation.

  • What are the limitations of standalone UV technology?

    Improper filtration, voltage fluctuation, scaling on quartz glass due to hardness in water, and incorrect flow (high) can make stand alone UV treatment ineffective. This leads to improper disinfection of drinking water.

  • What is the effect of inlet turbidity on performance of UV purifiers?

    If case of high turbidity in inlet water due to incorrect sediment filter fitment, over aging of pre filters can cause poor disinfection. Microbes in the water may escape penetration of UV rays resulting in poor kill.

  • Is the UV technology effective against hard water?

    UV technology is not effective against hard water. The hardness ions like Ca & Mg present in incoming water form scaling on the quartz sleeve present on the UV lamp during usage resulting in poor kill.

  • How does a UV purifier disinfect water?

    Ultraviolet disinfection is a well accepted natural, nonchemical, environmentally safe technique for purifying biologically contaminated waters. UV purifiers deactivate or paralyze disease causing microbes by altering genetic structure of cell and rendering them incapable of production there by making water pure.

FAQs on Alkaline Water 8 questions
  • What are other benefits of alkaline water/hydrogen rich water?

    It hydrates well because of its enhanced absorption.

    It helps to energize human body. It can be used as an astringent, washes out dirt and pesticides from fruits and vegetables. It improves quality and taste of food. It helps in weight management. It slows down aging.

  • What are other benefits of alkaline water/hydrogen rich water?

    It hydrates well because of its enhanced absorption.

    It helps to energize human body. It can be used as an astringent, washes out dirt and pesticides from fruits and vegetables. It improves quality and taste of food. It helps in weight management. It slows down aging.

  • What is the pH level of hydrogen water? Which is the crucial parameter for hydrogen water?

    Potency of hydrogen water is measured by its ORP level, generally ORP minus 600 to 800 is recommended along with a pH around 10.6

  • What are the health benefits of drinking alkaline water?

    Alkaline water is anti aging, Antitoxic, Anti allergic, helps in curing skin diseases, improves chronic health conditions like Arthritis, high blood pressure, osteoporosis.

    It boosts overall metabolism, helps controlling diseases like diabetes mellitus type II and radiation-induced adverse effects for liver tumor, Parkinson’s disease.

  • Do all alkaline water purifiers have add on purification systems?

    Alkaline water purifiers are equipped mostly with filtration systems or Ultra filtration purification system.

    Alkaline water purifier from Robinson India has two options of purification systems, Reverse osmosis system or non RO (ESS – Electrolytic sanitizing system – Silver ionizer)

  • What is hydrogen water? Do all alkaline water purifiers deliver hydrogen water as well?

    Hydrogen water is water rich in hydrogen.

    Due to unhealthy diets, stress, pollution, free radicals are produced in our body. Cells in our body attacked by these free radicals get damaged due to oxidation stress, this causes diseases, illness and aging. Hydrogen is the strongest antioxidant, it prevents oxidation of cells by neutralizing the damage causing free radicals.

    It boosts overall metabolism, helps controlling diseases like diabetes mellitus type II, and radiation-induced adverse effects for liver tumor, Parkinson’s disease.

    All Alkaline water purifiers do not deliver hydrogen water.

    Alkaline water purifier by Ion Exchange deliver hydrogen water with negative ORP which signifies the strength of hydrogen ion concentration.

  • Which alkaline water purifier should one buy?

    There are good number of alkaline water makers in the market. Alkaline water purifier in which alkaline water is produced by electrolysis of water, has potential health benefits, however one should check the relevant certification of performance for these products.

    Alkaline water purifier by Robinson India delivers alkaline water in 4 different options

    Hydrogen water pH 10.6
    Cooking pH 9
    Drinking pH 8.5
    Sanitizing pH 3-5

    We recommend alkaline water from Robinson India which has relevant certification for the performance.

  • What is alkaline water?

    Alkaline water, has a higher pH level than regular drinking water, it has significant health benefits because it can neutralize the acid in your body and improve your overall health. In a true alkaline water maker, alkaline water is made by electrolysis of water.

    Note that in the following scale 7 is neutral pH, above 7 is alkaline and below 7pH is acidic

    Alkaline water prepared from mineral based media cartridge do not have the potency for health benefits, thought these media based alkaline water makers may be low in cost. These non electric water ionizers cannot produce water with different levels of pH as in electrolytic alkaline water maker. The fixed pH level produced by non electric water ionizer is based on existing minerals in source water.

    Alkaline ionized water which is produced by electrolysis process has antioxidant properties.

FAQs on Boiler Water Treatment 87 questions
  • What is the difference between a corrective and preventative application of the treatment?

    In application terms basically nothing. A treatment period will be seen as corrective if scale and corrosion are present in the boiler from previous use. Treatment in a boiler using PT from new or containing no scale or corrosion will be preventative. In these circumstances there is nothing from past incomplete treatments to correct.

  • Explain the common metallurgical problems occur in the boiler?

    Common metallurgical problems are:

    Waterwall Tubes

    Most failures observed have been caused by overheating, both long and short-term. As the metal temperature rises above 900 F, the normal structure of the carbon and low alloy steels begins to break down, and carbide spheroidization occurs. Typical contributors to failure include:

    Waterside deposits
    Corrosion fatigue
    Hydrogen damage
    Caustic/acid phosphate gouging
    Ash Corrosion
    Flame Impingement         

    Floor Tubes

    Floor tube failures occur when a thermal differential exists, with the top half of the tube becoming hotter than the bottom half. Deposits plate out, leading to under deposit corrosion mechanisms. The tube often fails by overheating.

    Roof Tubes

    Most roof tube failures can be attributed to corrosion fatigue or internal corrosion, such as hydrogen damage.

    Economizer Tubes

    The majority of all economizer failures occur by oxygen corrosion, erosion, or thermal fatigue.

    Super heater Tubes

    Like water wall tube failures, most problems arise from overheating. The most susceptible areas are lead tubes and tube bends. Common causes of failure include:

    High temperature, liquid-phase corrosion
    Vanadium attack (oil-fired units)
    High temperature oxidation
    Creep rupture failures
    Dissimilar metal weld failures 


    Most failures occur at the circumferential weld connections or at the tube stub weld. Circumferential cracking can be observed at or near the weld, and is attributable to thermal expansion fatigue and/or creep damage.

    Steam/Mud Drum

    Generating tubes at the rolled-in end of the drum may have small circumferential cracks on the inside of the tube. These cracks are attributable to corrosion fatigue brought on by thermal or mechanical stresses.

    Dissimilar Metal Welds

    Tube tie welds or dissimilar metal welds are often made from a stainless steel or nickel base alloy. Problems arise from the difference in thermal expansion coefficients between the austenitic and ferritic weld, causing cracking.


    High energy piping systems, including main steam, hot reheat steam and cold reheat steam lines, often fail by creep damage as a result of long- term service at elevated temperatures under stress. Fatigue and fabrication defects may also play a role. Girth welds tend to leak-before-break, while longitudinal seams may have more catastrophic and unpredictable ruptures. Feed water piping is susceptible to flow-accelerated corrosion (FAC), caused by the dissolution of the protective oxide layer.  

  • What is the application of Neutralizing amine?

    Neutralizing amines are high pH chemicals that can be fed directly to the feedwater or the steam header to neutralize the carbonic acid formed in the condensate (acid attack).

    The three most commonly used neutralizing amines are morpholine, diethyleminoethanal (DEAE) and cyclohexylamine. Neutralizing amines cannot protect against oxygen attack; however, it helps keep oxygen less reactive by maintaining an alkaline pH.

  • What is the application of polymers in boiler water treatment?

    Most polymers used in feed water treatment are synthetic. They act like chelates but are not as effective. Some polymers are effective in controlling hardness deposits, while others are helpful in controlling iron deposits. Polymers are often combined with chelates for the most effective treatment.

  • What is the application of filming amine?

    Filming amines are various chemicals that form a protective layer on the condensate piping to protect it from both oxygen and acid attack.

    The filming amines should be continuously fed into the steam header with an injection quill based on steam flow. The two most common filming amines are octadecylamine (ODA) and ethoxylated soya amine (ESA).

    Combining neutralizing and filming amine is a successful alternative to protect against both acid and oxygen attack

  • What are the causes of mechanical fatigue?

    Fatigue is the result of cyclical stresses in the component. Distinct from thermal fatigue effects, mechanical fatigue damage is associated with externally applied stresses.

    Stresses may be associated with vibration due to flue gas flow or soot blowers (high-frequency low-amplitude stresses), or they may be associated with boiler cycling (low-frequency high-amplitude stress mechanism).

    Fatigue failure most often occurs at areas of constraint, such as tube penetrations, welds, attachments or supports.

  • What are the causes of erosion?

    Erosion of tube surfaces occurs from impingement on the external surfaces. The erosion medium can be any abrasive in the combustion gas flow stream, but most commonly is associated with impingement of fly ash or soot blowing steam.

    In cases where soot blower steam is the primary cause, the erosion may be accompanied by thermal fatigue.

  • What are the symptoms of erosion?

    Tube experiences metal loss from the OD of the tube. Damage will be oriented on the impact side of the tube. Ultimate failure results from rupture due to increasing strain as tube material erodes away.

  • What are the causes of graphitization?

    Long-term operation at relatively high metal temperatures can result in damage in carbon steels of higher carbon content, or carbon-molybdenum steel, and result in a unique degradation of the material in a manner referred to as graphitization.

    These materials, if exposed to excessive temperature, will experience dissolution of the iron carbide in the steel and formation of graphite nodules, resulting in a loss of strength and eventual failure.

  • What are the causes of Long term over heat?

    Long-term overheat occurs over a period of months or years. Super heater and reheat superheater tubes commonly fail after many years of service, as a result of creep.

    During normal operation, alloy superheater tubes will experience increasing temperature and strain over the life of the tube until the creep life is expended. Furnace water wall tubes also can fail from long-term overheat.

    In the case of water wall tubes, the tube temperature increases abnormally, most commonly from waterside problems such as deposits, scale or restricted flow. In the case of either superheater or water wall tubes, eventual failure is by creep rupture.

  • What are the symptoms of Long term over heat?

    The failed tube has minimal swelling and a longitudinal split that is narrow when compared to short-term overheat.

    Tube metal often has heavy external scale build-up and secondary cracking.

  • What are the causes of short term over heat?

    Short-term overheat failures are most common during boiler start up. Failures result when the tube metal temperature is extremely elevated from a lack of cooling steam or water flow.

    A typical example is when superheater tubes have not cleared of condensation during boiler start-up, obstructing steam flow. Tube metal temperatures reach combustion gas temperatures of 1600°F or greater which lead to tube failure.

  • What are the symptoms of short term over heat?

    Failure results in a ductile rupture of the tube metal and is normally characterized by the classic “fish mouth” opening in the tube where the fracture surface is a thin edge.

  • What are the causes of Fireside Corrosion Fatigue?

    Damage initiation and propagation result from corrosion in combination with thermal fatigue.

    Tube OD surfaces experience thermal fatigue stress cycles which can occur from normal shedding of slag, soot blowing or from cyclic operation of the boiler.

    Thermal cycling, in addition to subjecting the material to cyclic stress, can initiate cracking of the less elastic external tube scales and expose the tube base material to repeated corrosion.

  • What are the symptoms of Fireside Corrosion Fatigue?

    Tubes develop a series of cracks that initiate on the outside diameter (OD) surface and propagate into the tube wall. Since the damage develops over longer periods, tube surfaces tend to develop appearances described as “elephant hide,” “alligator hide” or craze cracking.

    Most commonly seen as a series of circumferential cracks. Usually found on furnace wall tubes of coal-fired once-through boiler designs, but also has occurred on tubes in drum-type boilers.

  • What are the causes of Waterwall Fireside Corrosion?

    Corrosion occurs on external surfaces of water wall tubes when the combustion process produces a reducing atmosphere (sub stoichiometric). This is common in the lower furnace of process recovery boilers in the pulp and paper industry.

    For conventional fossil fuel boilers, corrosion in the burner zone usually is associated with coal firing. Boilers having maladjusted burners or operating with staged air zones to control combustion can be more susceptible to larger local regions possessing a reducing atmosphere, resulting in increased corrosion rates.

  • What are the symptoms of Waterwall Fireside Corrosion?

    External tube metal loss (wastage) leading to thinning and increasing tube strain.

  • What are the causes of High-temperature Oxidation?

    High-temperature oxidation can occur locally in areas that have the highest outside surface temperature relative to the oxidation limit of the tube material. Determining the actual root cause between the mechanisms of ash corrosion or high-temperature oxidation is best done by tube analysis and evaluation of both ID and OD scale and deposits.

  • What are the causes of Super heater Fireside Ash Corrosion?

    Fireside ash corrosion is a function of the ash characteristics of the fuel and boiler design. It usually is associated with coal firing, but also can occur for certain types of oil firing. Ash characteristics are considering the boiler design when establishing the size, geometry and materials used in the boiler.

    Combustion gas and metal temperatures in the convection passes are important considerations. Damage occurs when certain coal ash constituents remain in a molten state on the super heater tube surfaces. This molten ash can be highly corrosive.

  • What are the symptoms of Super heater Fireside Ash Corrosion?

    External tube wall loss and increasing tube strain. Tubes commonly have a pock-marked appearance when scale and corrosion products are removed.

  • What are causes of water side corrosion fatigue?

    Tube damage occurs due to the combination of thermal fatigue and corrosion. Corrosion fatigue is influenced by boiler design, water chemistry, boiler water oxygen content and boiler operation.

    A combination of these effects leads to the breakdown of the protective magnetite on the ID surface of the boiler tube.

    The loss of this protective scale exposes tube to corrosion. The locations of attachments and external weldments, such as buck stay attachments, seal plates and scallop bars, are most susceptible. The most likely to progress during boiler start-up cycles.

  • What are the symptoms of water side corrosion fatigue?

    ID initiated, wide trans granular cracks which typically occur adjacent to external attachments.

  • What are the causes of stress corrosion cracking?

    SCC most commonly is associated with austenitic (stainless steel) superheater materials and can lead to either trans granular or inter granular rack propagation in the tube wall.

    It occurs where a combination of high tensile stresses and a corrosive fluid are present. The damage results from cracks that propagate from the ID.

    The source of corrosive fluid may be carryover into the super heater from the steam drum or from contamination during boiler acid cleaning if the super heater is not properly protected.

  • What are the symptoms of Stress corrosion cracking?

    Failures from SCC are characterized by a thick wall, brittle-type crack. May be found at locations of higher external stresses, such as near attachments.

  • What are the symptoms of acid attack?

    Corrosive attack of the internal tube metal surfaces, results in an irregular pitted or, in extreme cases, a” Swiss cheese” appearance of the tube ID.

  • What are the causes of hydrogen damage?

    Hydrogen damage is most commonly associated with excessive deposition on ID tube surfaces, coupled with a boiler water low pH excursion.

    Water chemistry is upset, such as what can occur from condenser leaks, particularly with salt water cooling medium, and leads to acidic (low pH) contaminants that can concentrate in the deposit. Under-deposit corrosion releases atomic hydrogen which migrates into the tube wall metal, reacts with carbon in the steel (decarburization) and causes inter granular separation.

  • What are the symptoms of hydrogen damage?

    Inter granular micro-cracking. Loss of ductility or embrittlement of the tube material leads to brittle catastrophic rupture

  • What are the causes of Oxygen pitting?

    Oxygen pitting occurs with the presence of excessive oxygen in boiler water. It can occur during operation as a result of in-leakage of air at pumps, or failure in operation of preboiler water treatment equipment.

    This also may occur during extended out-of-service periods, such as outage sand storage, if proper procedures are not followed in lay-up.

    Non-rainableocations of boiler circuits, such as super heater loops, sagging horizontal super heater and re heater tubes, and supply lines, are especially susceptible. More generalized oxidation of tubes during idle periods is sometimes referred to as out of- service corrosion. Wetted surfaces are subject to oxidation as the water reacts with the iron to form iron oxide.

    When corrosive ash is present, moisture on tube surfaces from condensation or water washing can react with elements in the ash to form acids that lead to a much more aggressive attack on metal surfaces.

  • What are symptoms of Oxygen pitting?

    Aggressive localized corrosion and loss of tube wall, most prevalent near economizer feedwater inlet on operating boilers. Flooded or non-drainable surfaces are most susceptible during outage periods

  • What are the causes of caustic attack?

    Caustic attack occurs when there is excessive deposition on ID tube surfaces. This leads to diminished cooling water flow in contact with the tube, which in turn causes local under-deposit boiling and concentration of boiler water chemicals. If combined with boiler water chemistry up sets of high pH, it results in a caustic condition which corrosively attacks and breaks down protective magnetite

  • What are the symptoms of caustic attack?

    Localized wall loss on the inside diameter (ID) surface of the tube, resulting in increased stress and strain in the tube wall.

  • There is corrosion problem in the pressure parts on F.W. circuit, how to overcome the problem?

    i) Check proper deaeration in the Deaerator. D.O. should be less than 7PPB
    ii) Maintain N2H4 at desired level in the BFW
    iii) Maintain pH more than 9 in the CBD water
    iv) Closely monitor TSP level in the CBD water
    v) Check feasibility of change over of BFW treatment to AVT
    vi) Verify for proper selection of oxygen scavenger if used

  • Blow down losses are heavy, how to reduce blow down rate?

    i) Monitor boiler water treatment. All volatile treatment is better than conventional treatment if there is techno-economical feasibility
    ii) Check water treatment process for seepage of Chloride, Silica, etc. Check TSP quality for Chloride content
    iii) Fine control of CBD with increased frequency of Blow down water will help in saving of energy & boiler water

  • Soot deposition in my boiler is heavy. How to reduce soot formation and deposition?

    The reasons for heavy soot deposition are:
    i) Poor quality of fuel with higher ash content metals, high insolubility. Ensure the quality of fuel
    ii) Poor combustion- improve the combustion by checking Atomizing Steam pressure by cleaning burner tip and fuel oil system filters and checking viscosity near burner tip.

  • How to improve poor boiler steam-fuel ratio and increase boiler efficiency?

    For occasional low efficiency- clean the burner tips and fuel oil pumps filters, check for viscosity of fuel oil, burner tip holes and atomizing steam pressure.

    For continuously low efficiency- check flame colour, if the colour of the flame is not bright golden yellow, combustion is poor. Take remedial measures mentioned as above and additionally check the following.

    If stack temperature is high, there is soot deposition in the boiler. Stop the boiler and carry out cleaning of the boiler. Check water side deposition/ scale formation. If scale formation is observed, plan for cleaning the boiler with appropriate method. Evaluate for installation of economizer and soot blowing frequency.

  • How do I dry lay up a boiler?

    Drain, clean, allow time to dry, insert desiccant or hydrated lime to absorb the oxygen, and carefully seal the boiler to prevent air leaks. Inspect the desiccant or hydrated lime periodically.

  • How do I wet lay up a boiler?

    If you plan on keeping your boiler idle for more than a month, dry lay-up is the preferred method. If the boiler needs to be readily available to service.

    Add additional sulfite and alkalinity (if you are using an acidic sulfite) to the boiler. Maintain at least 100ppm of sulfite and check sulfite residuals weekly.

    Also, it is important to ensure the boiler tubes stay fully in the water to prevent tube corrosion.

  • How do I feed my chemicals?

    Preferably neat (straight from the drum). It provides a more consistent chemical dilution.

  • Where do I feed my chemicals?

    Sulfite and alkalinity to the feedwater tank or drop leg of a Deaerator Phosphate/Polymer to the feedwater line or drop leg of a Deaerator or steam drum.

    Amine preferred to the steam header, but you can feed it to the feedwater line or drop leg of a Deaerator. One drum program or day tank to the feedwater line or drop leg of a Deaerator.

  • How do I prevent boiler scale?

    1) Have a good operating softener
    2) Make sure the brine tanks is half filled with salt at all times
    3) Perform softener hardness and feedwater checks daily
    4) If using a phosphate chemical program, blowdown the boiler two times a day

  • How do I remove boiler scale?

    One solution is to hire an outside company that specializes in acid cleaning. If scale is light, do not remove the scale, just make sure your softeners are functioning properly and use a polymer designed for gradual scale removal.

  • What is cycles of concentration?

    Cycles of Concentration is refers to how many times you reuse your water. The purpose of a boiler is to reuse water. To calculate your cycles of concentration divide your boiler water silica residual by your feedwater silica.

  • What is boiler make-up water?

    Make-up water is referred to as the fresh water that is added to the feedwater tank.

  • Why do I have to return my condensate?

    Condensate is hotter than make-up water and it contains valuable BTUs. The warmer the feedwater in the tank, the less energy you need to heat the water to make steam. So it is important to return as much condensate as possible.

  • What is boiler feedwater?

    Boiler feedwater is referred to as the water entering the boiler. It is a mixture of returned condensate and fresh make-up water.

  • What should be the boiler temperature of water?

    The boiling point of water depends on pressure. At atmospheric pressure, water boils at 100°C. As pressure increases, the boiling point increases. At 22,000 kPa, where water is converted to steam, the boiler point is lowered.

  • What items are common boiler failures?

    1) Oxygen Pitting
    2) Short-Term Overheating
    3) Long-Term Overheating
    4) Caustic Gouging

  • What is the boiler chemical amine?

    There are two main categories of amines, neutralizing amines and filming amines.

    Neutralizing amines are the most common. Amines are designed to increase the condensate pH to minimize condensate corrosion.

    Make sure to check how your steam is being used. In some applications, there may be restrictions on using amines.

  • What boiler tests should I perform?

    If you do not have man power or time to perform a bunch of tests. We recommend testing at minimum the boiler water sulfite residual, boiler water conductivity, and feedwater/softener hardness.

    Also, we recommend monitoring your chemical inventory daily as a double check to ensure sufficient chemical is being added to the chemical.

  • What is a Deaerator?

    A deaerator is mechanical way of removing dissolved oxygen from the water. There are different types of deaerators and multiple manufactures.

    Remember you still need to feed an oxygen scavenger to remove the dissolved oxygen that the deaerator does not remove.

  • Why is my boiler scale only on my bottom tubes?

    If you have poor performing softeners, if your softeners are being by-passed, or if you do not have softeners or hard water is entering the boiler.

    Remember phosphates and polymers are only used as polishers to remove the minimal amounts of Calcium and magnesium that enter the boiler.

    Your pre-treatment is designed to remove 95% of the calcium and magnesium. If you are using a straight phosphate program with no polymer, make sure to perform bottom blowdown twice a day. A phosphate chemical is designed to sink to the boiler bottom after the calcium and magnesium is attached.

  • Why is my boiler water red?

    If your boiler water is red in appearance, it may be from a number of possible reasons. Some of the most common ones are:

    1) Inadequate levels of sulfite
    2) Over feeding alkalinity
    3) Condensate contamination
    4) Overfeeding an acidic sulfite product that depresses the boiler water pH
    5) Low alkalinity

  • How much do I need to blowdown my boiler?

    It depends on how many impurities you have in your feedwater.

    The goal is to determine what the limiting factor is (dissolved solids, alkalinity, silica, or iron) in your boiler water and set your blowdown setting at that limit.

    To determine the amount of blowdown percentage divide 1 by your concentration ratio and multiply by 100.

  • What is boiler blowdown?

    Blowdown is the removal of the concentrated dissolved and suspended solids. By blowing down the water from the system, lower concentrated water dilutes the existing water in the boiler.

  • How do I calculate how much condensate is returning back as a boiler feed?

    To calculate your return condensate percentage multiply 100 by 1-(feedwater silica/makeup water silica)

  • Why do I have to feed sulfite to my boiler?

    Sulfite is referred to as an oxygen scavenger. Sulfite is the most commonly used oxygen scavenger. It is used to eliminate or replace dissolved oxygen.

  • What is a single drum program?

    A single drum program is referred to as a chemical mixture that contains all the boiler chemical components (sulfate, amine, phosphate/polymer, and alkalinity) in one container.

  • Why do I need to feed a polymer or phosphate to my boiler?

    Phosphate and polymers are required in boilers to prevent the calcium and magnesium from precipitating to the boiler tubes.

    Theoretically, some calcium and magnesium will leak though the softener.

    The calcium and magnesium minerals attach themselves to the polymer or phosphate and are discharged either through surface blow down or during bottom blow downs.

  • What is boiler carryover?

    If your boiler water suspended solids are excessive, some solids may collect on the surface of a steam bubble and exit the boiler with the steam.

  • Why are condensate pipes leaking or excessively corroding?

    Corrosion occurs from carbonic acid and oxygen pitting. Carbonic acid occurs from CO2 which is a breakdown molecule of the carbonate alkalinity condensing from water to form H2CO3.

    Oxygen pitting occurs as steam condenses and the vacuum created pulls air into the condensate system.

  • What tests should I perform on my condensate system?

    1) Insoluble and soluble iron
    2) Condensate pH (7.5-8.5 for most systems) at the furthest point from your boiler and possibly at multiple locations if your system is large
    3) Condensate corrosion coupons

  • Why did my feed water pump fail due to excessive corrosion?

    If your feedwater pump has experienced excessive corrosion and/or failure it is most likely from inadequate amount of sulfite being fed to the feedwater tank.

    Make sure your sulfate is fed to the feed water tank and that it is being feed though an injection quill that reaches near the center of the tank.

  • Is Porta Treatment OK with brass tubes?

    No, Porta Treatment can not be used with brass tubes.

  • Is the regime identical for boilers with copper fireboxes and/or tubes?

    Not quite. There are couple of alterations with a lower TDS and pH required but that is about it. Dosing and monitoring remain the same whilst results will be little different.

  • Would PT treated water descale and treat corrosion if left standing in a boiler or tanks when not in use?

    Yes, absolutely. The period of time to fully correct such problems is hard to predict as each case is different, but the effect of such a treatment period will only be positive.

  • Our locomotive stands idle for several months every year. How does this effect an application?

    No problem! PT treated water should, where frost is not going to be a problem, be left in water tanks and boilers. It continues to work when a locomotive is not in use. Thus it is much better to leave tanks and boilers filled rather than in empty and so-called “dry” conditions.

  • Does PT stop corrosion and scale in water tanks, pipes and injectors?

    Yes. Old scale and corrosion will be treated over time but this can be a slow process due to the much lower levels of chemical concentration in these parts.

  • What happens in feedwater heaters?

    These should be as clean as possible to start with. In time they will be descaled and corrosion will be prevented but it will be a slower process than in the boiler. New items will remain scale and corrosion free.

  • How often should a loco be washed out?

    This varies and is results-driven. Once a year is fully possible when the treatment is operating as a preventative one rather than a corrective one.

  • How often should a loco be blown down?

    This depends on the results obtained when monitoring the boiler water. Few times per annum can be said to be normal.

  • It sounds complicated to monitor?

    It is not. Only two boiler water parameters are to be measured and only a few remedies to incorrect conditions exist; these being blowdown and alkalinity regulation.

  • Is it complicated to administer?

    It is not. A pre-prepared chemical mix is added to the locomotive’s tank to treat the water on a regular basis.

    Long periods of standing without operation of any injectors will reduce the active antifoam concentration below safe levels. In such cases extra antifoam may be required depending on operating circumstances.

  • Why the water source is of no concern at all?

    The high alkalinity created acts as a buffer to incoming water variation.

  • Why would I use something experimental on my loco?

    Pretreatment (PT) is no experiment. It is a fully developed water treatment based on highly successful previous treatments.

    It takes these further due to improvements in the understanding of various phenomena and the availability of more effective and relevant chemicals. It should also be remembered PT was developed for locomotives.

  • Boiler tubes are consumable items so what does it matter?

    They need not be! PT offers a 20+ year life from boiler tubes where regulation so allows. The lack of corrosions and thermal fatigue failures also, of course, extend to all other parts of the boiler. Corrosion prevention is just one part of the overall benefits available from using PT.

  • Why should I care about steam purity?

    Because it leads to salts being deposited in the steam passages causing accelerated internal corrosion and hot spots (failed superheater elements, pipes etc).

    It leads to solids being carried to the valves and pistons acting as a grinding paste when mixed with liquids and it leads to contaminated and thus compromised lubrication.

    All these are equally true for any auxiliary item of equipment that use steam, e.g.: air pumps, generators etc.

  • Doesn’t high alkalinity dissolve brasses and bronzes?

    Only up to certain point. Experience shows it is important not to have leaking valves situated below the normal water level. Such valves seats and stems, when made of brass or bronze. It should ideally be substituted by stainless steel or other alkaline-resistant materials. Note ONLY the seat and stem need replacement. Erosion of the component body will be very slow indeed.

    Doesn’t high alkalinity dissolve glass, i.e.: gauge glasses.

    Silica is dissolved gradually by alkalinity. Correct maintenance policies based on inspection, on set days, in steam will prevent problems occurring with tubular glasses. It is best to use reflex glasses if possible. Failures of these flat glasses are virtually unheard. The ability to dissolve silica ensures silica scale does not form on boiler surfaces.

  • Can I use lead mud hole door seals?

    No. Lead is rapidly eroded when alkalinity reach or exceed pH12. An alternative must be used.

  • I use lead fusible plugs. Is this OK?

    No. Lead is rapidly eroded when alkalinity reach or exceed pH12. A number of alternatives are available:

    a. Lead/tin alloy plugs which give a 90+ day life and longer with copper electroplating on the water side;

    b. Copper electroplated (on the water side) pure lead plugs;

    c. Drop (button) plugs.

  • What happens to all the mud and clay build up? Surely this would make it impossible to run for very long without a washout?

    Any solids which would have formed mud’s or clays will either go into solution (due to the alkalinity) or will go into suspension in the boiler water.

    However those particles in suspension, again due to the alkalinity, form a totally mobile sludge which moves with the slightest water current, even when cold.

    It is not in any way adherent. Under high steam demand, and thus rapid boiler water circulation, this sludge fully mixes with the boiler water and appears as a brown color in the gauge glasses.

  • Is Line side treatment more effective?

    It is not. Direct chemical treatment of boiler water can totally solve fouling, corrosion, caustic embrittlement and steam contamination problems.

    Line side treatments can only ease the problems of fouling and caustic embrittlement but can not deal with corrosion or steam contamination.

  • Aren’t high alkalinity dangerous?

    History does not show the risk to be serious if simple maintenance and operating policies are followed.

  • Won’t the high alkalinity cause caustic embitterment?

    Caustic embrittlement is a complex problem with multiple causes. The use of specific tannins have been shown to prevent it. Additionally leak-free boilers allow no opportunity for caustic embrittlement to occur.

  • Won’t my boiler leak with no scale present?

    Initially maybe, but a scale-free boiler can be made leak-free by a good boiler smith. Minor leaks will be plugged by the tannin in the treatment.

    Also it should be remembered many leaks are actually caused by scale, which has led to localized overheating, or corrosion.

    Even a “traditional” boiler of riveted and expanded construction ought to be leak-free and PT will make sure no localized overheating or corrosion will ever occur to cause leaks.

  • What happens to all the scale which would normally form in the boiler?

    It is dissolved in the boiler water or precipitates out as part of the mobile sludge which is formed.

  • What is boiler scale?

    The most common scale is white in appearance and is from calcium carbonate that has precipitated from hard feed water.

    Hard water contains calcium and magnesium and minerals that are hard to wash. Silica scale is brittle and has a glassy appearance. The most common scale is white in appearance and is formed by calcium carbonate that has precipitated from hard feed water.

  • Why do I have to chemically treat my boiler?

    1) To prevent boiler scale
    2) To minimize corrosion to the feed water and steam & condensate system
    3) Improve boiler efficiency
    4) Reduce fuel, operating and maintenance costs
    5) Minimize maintenance and downtime

FAQs on Chlorine dioxide 10 questions
  • Can Chlorine Dioxide be stored safely?

    Solutions of approximately 1% ClO2 (10 g/L) may safely be stored at 5°C for several months, with little change in concentration, provided that the solution has no gas space and is protected from light.

  • Is Chlorine Dioxide expensive?

    The cost of chlorine dioxide is dependent on the cost of the precursor chemicals sodium chlorite or sodium chlorate-and the chemicals required to convert these chemicals into ClO2.

    The cost of ClO2 will also depend on the generation method employed. When compared to the cost of chlorine, the cost of ClO2 is higher. However in those instances in which chlorine is not the preferred regulatory or environmental alternative, ClO2 is a very attractive alternative.

    The capital equipment costs of generating ClO2 are also far less than that of other alternatives like ozone which can also be used for water treatment.

  • How is Chlorine Dioxide made?

    Chlorine dioxide may be prepared chemically from either sodium chlorite or sodium chlorate or generated electrochemically.

  • Is Chlorine Dioxide a commodity chemical (i.e. can I purchase it directly from a chemical supplier)?

    Pure chlorine dioxide cannot be purchased in solid, liquid or gaseous form. In fact, because ClO2 is such a highly effective and reactive chemical, transportation of ClO2 is not permitted. Chlorine dioxide must be produced and used at the point of application. Chlorine dioxide generators are automated and user friendly.

    Chlorine dioxide generator -Chlogen

  • Is Chlorine Dioxide toxic?

    Fifty years of worker experience has demonstrated that ClO2 is a safe compound when handled properly. World-wide, nearly 4.5 million pounds per day of chlorine dioxide are used in the production of pulp and paper. However, as with any and

    all disinfectant chemicals, if handled improperly, or consumed internally or absorbed or subjected to prolonged exposure, ClO2 can be toxic. However, it is also this toxicity that makes ClO2 a good water disinfectant agent

  • Why should I use Chlorine Dioxide rather than Chlorine for water treatment?

    It should first be noted that both chlorine and chlorine dioxide are powerful and effective disinfectants.

    Chlorine has been and continues to be a very effective disinfectant which is responsible for making and keeping drinking water safe for people around the world. In the instances in which the drinking water source is surface water, which contains organic materials, ClO2 offers the following benefits- First, ClO2 functions via an oxidative rather than chlorinating reaction.

    This virtually eliminates the formation of chlorinated organic compounds which are suspected to increase cancer risk. Second, ClO2 is generated on site, thereby eliminating the need for site storage of chlorine and/or transportation thereof .

  • How does the use of Chlorine Dioxide affect the environment?

    Chlorine dioxide is environmentally friendly and in fact is a pollution protection technology that protects the environment and human health from bacteria and by-products formed from other disinfection methods.

    For example, in the pulp and paper industry the use of ClO2 has virtually eliminated dioxin in mill waste water and has led to a significant improvement in the aquatic eco-system.

  • Does Chlorine Dioxide have any uses other than municipal water treatment?

    Chlorine dioxide is used extensively as a bleaching agent in the pulp and paper industry. In fact, in order to minimize the environmental effects of the bleaching process, ClO2 is rapidly becoming the chemical of choice.

    Chlorine dioxide is also being used as a disinfectant agent in the food industry for fruit and vegetable washing, flume water disinfection, meat and poultry disinfection, food process equipment sanitizing and for odor control.

    In industrial processes, ClO2 is used in industrial water treatment (cooling systems/towers), ammonia plants, pulp mills (slime control, paper machines), oil fields, scrubbing systems/odor control, textile bleaching and the electronic industry. Chlorine dioxide is also applied to medical wastes.

    As prominently reported in the US National Media, chlorine dioxide gas is also very effective in remediating environments which have been contaminated with Anthrax spores.

  • How is Chlorine Dioxide used in water treatment applications? How does it work?

    ClO2 is used principally as a primary disinfectant for surface waters with odor and taste problems. It is an effective biocide at concentrations as low as 0.1 ppm and over a wide pH range.

    ClO2 penetrates the bacteria cell wall and reacts with vital amino acids in the cytoplasm of the cell to kill the organism. The by-product of this reaction is chlorite. Of importance is that toxicological studies have shown that ClO2‘s disinfection by-product, chlorite, poses no significant adverse risk to human health.

  • Is Chlorine Dioxide the same as Chlorine?

    While chlorine dioxide (ClO2) has chlorine in its name, chlorine dioxide’s chemistry is radically different than that of chlorine.

    One atom can make all the difference in the world. The difference between chlorine and ClO2 stems from their dissimilar chemical structure- and this is what accounts for their distinct chemical behaviors.

    Similarly, hydrogen is an explosive gas. But when combined with oxygen, it becomes dihydrogen oxide-commonly known as water.

FAQs on Demineralization Plants | DM Plants 10 questions
  • How is conductivity of DM water measured?

    Conductivity is measured using conductivity meter which have two basic elements: a conductivity cell with electrodes of special design between which demineralized water flows and a sensitive milliammeter for measuring the current passing between the electrodes. This current is proportional to conductivity of the water.

  • What is a degasser tower?

    The alkalinity or bicarbonates and carbonates present in raw water appear as carbonic acid or dissolved carbon dioxide at the outlet of cation exchanger. Weak base anion resin does not remove weak acids such as carbon dioxide or silica.

    The demineralized water is therefore passed through a degassing tower for removal of carbon dioxide or CO2. The tower, made of rubber-lined steel is filled with packing rings through which the demineralized water percolates. Low pressure air introduced at the bottom of the tower scrubs out CO2, and the degassed water collects in a sump beneath the tower.

  • What is counter-current flow regeneration?

    With counter-flow regeneration, the regenerant acid or caustic passes in the direction opposite to the flow of water during  the service cycle. With counter-flow regeneration, the fresh regenerant  enters  at the bottom of the resin bed and passes in an upward direction (opposite to the downflow direction during service cycle- or counter-current).

    Hence, bottom layer of the resin bed is always in highly regenerated condition. This means lower leakage or slip of  ions during the service cycle producing better quality of treated water than the co-current method.

  • How do I size a demineralization plant?

    For the sizing of a demineralization plant, a good in-depth water analysis is normally required which gives the breakdown of total anions and total cations and any potential organic foulants. The final water quality specification, as well as flow rate and water used per day is required.

  • What is the quality of the treated water from a demineralization plant?

    Electrical conductivity is used to express the purity of demineralized water. Depending on the application pH and/or reactive silica in DM water may also be specified as parameters to measure the purity of DM water.

    The quality of the water depends on the type of scheme used:

    Cation-Anion-Polishing Mixed Bed
    For standard plants our guarantees are as follows:
    1) Conductivity 0.1 micromhos /cm-1.0 micromhos/cm. at 25 C (We guarantee conductivity of 0.1 micromhos/cm in  very large projects only)
    2) Sodium 0.01 mg/l  – pH: 7 +/- 0.2
    3) Reactive silica 0.02 mg/l -0.05 ppm

    Cation-Anion (Counter-Current Regeneration)
    For standard plants our guarantees are as follows:
    1) Conductivity 0.5 to 1.0 猶/cm at 25蚓- 30 micromhos/cm  (We guarantee conductivity less than 10 micromhos/cm in large projects only)
    2) Sodium 0.05 to 0.1 mg/l –  pH: 7.5 – 9.0
    3) Reactive silica 0.025 mg/l – less than 0.5 ppm (with FF-IP we  can guarantee less than say 0.3 ppm)

    Cation-Anion (Co-Current Regeneration)
    With typical co-current regeneration, the outlet quality will depend on the regenerant applied, resin employed and raw water quality
    1) Conductivity 5 to 30 S/cm at 25 Degree Celsius- conductivity can be upto 2 to 5 % of conductivity of raw water
    2) Sodium 0.5 to 3 mg/l
    3) Silica 0.1 to 0.3 mg/l – less than 1.0 ppm

  • What is mixed-bed demineralization?

    The mixed bed is a single column of  cation exchanger and anion exchanger  mixed together. Water passing through the column comes into contact with these materials and is subjected to almost infinite number of demineralizing stages. Thus DM water of extreme purity is produced.

    As with two-bed demineralizers, mixed bed units are regenerated with acid and alkali: but the ion exchange resins must be separated before this can be done. Bed separation is accomplished by backwashing: this carries the lighter anion resin to the top of the bed and the heavier cation sinks to the bottom.

    Two completely separated layers are thus formed, into which the acid and alkali solutions and rinse water are introduced through specially designed distributors. After regeneration, the two resins are mixed with compressed air.
    Normally mixed bed unit treats water from the two-bed DM plant that is already of high purity and their ionic load is low. They can consequently be operated at high flow rates, and are of relatively smaller size.

  • What is co-current flow regeneration?

    The regeneration is usually carried out in three steps. Firstly, the ion exchange column is backwashed with an upflow of water. The pressure vessel has about 50% free space above the resin bed (known as free board).

    This free space allows removal of any entrained solids, and re-classification of the resin bed by backwashing. Backwashing also relieves bed compaction.

    Secondly, a predetermined amount of acid or alkali is injected into the column in a downward direction (same direction as the service flow or co-current) to displace sodium/calcium/magnesium in the cation exchanger and chlorides/sulphates/alkalinity in the anion exchanger taken up during the service cycle. Lastly, the column is rinsed to remove excess regenerant. The entire operation takes about 3 hours for a two-bed DM plant.

  • Why are there numerous types of resins used in DM plant?

    The type of resins employed and selected depends on numerous factors: Treated water quality required- If silica removal is not required, anion exchange resin used  in two- bed  DM plants ,it is usually weak base anion resin. If silica level of 1.0 ppm can be tolerated, then strong base Type -2 resin is offered. When water free from silica is required, the anion exchanger is charged with  strong base Type -1 anion resin.

    • Input water quality
      Presence of organic foulants- In cases where water has high level of organic foulants such as humic and fulvic acids occurring in natural surface waters, Macroporous resins such as Type 1 strong base resin are better suited for the application than cation
    • Flow through plant required
    • Considerations of minimization of operating costs in terms of regenerant chemical consumption: In order to  reduce regenerant chemical consumption in large plants, anion resin (which is very efficient for removal of strong acids such as HCl and H2SO4 with minimal requirement of alkali for regeneration) is used in combination with cation strong base resin which is best suited for removal of weak acids such as carbon dioxide and silica from water

  • What is demineralized DM water used for?

    The high-purity water from a demineralization plant is typically used as feed water for high pressure boilers in many industries; as wash water in computer chip manufacture and other micro-electronics manufacturing processes, as pharmaceutical process water, and any process where high-purity water is a requirement.

    DM water is used as process water in the manufacture of chemicals and fertilizers, food products such as soft drinks, automobiles for rinsing of parts, textiles, etc.

    Two-bed DM plants are made in all sizes, from small portable units for laboratories to large multi-stream installations for Thermal power stations, refineries, petrochemical and steel plants.

  • What is a Demineralization Plant ( DM Plant )?

    Demineralization plant is employed for removal of minerals or dissolved salts from the water. Salts on dissolving dissociate into electrically charged particles called ions: for example common salt  will be split into sodium ion (a positively charged ion or cation) and chloride (a negatively charged ion or an anion).

    If such a solution is brought into contact with a suitable ion exchange material (called resin), some ions from the solution are taken up by the resin and an equivalent number are transferred from the resin to the solution. Ion exchange is thus a reversible interchange of ions between a liquid and a solid.

    A simple Demineralization Plant consists of two beds of chemically treated resin beads operating in series. The first column- cation exchanger- converts the dissolved solids in the raw water to the equivalent acids; these acids are removed as the water passes through the second column- anion exchanger.

    The final product from this process consists essentially of  pure water. When exhausted, the cation exchange resin is regenerated with acid and the anion exchange resin with alkali.

    In essence the DM plant comprises of  resin vessels with charge of strong cation and anion resin; control-panel encompassing a conductivity measurement and alarms, etc; acid and caustic injection facility from bulk, semi-bulk or carboy containers.

FAQs on Drinking water purifiers 23 questions
  • Whether recycled water can be used for household applications?

    Yes, recycled water can be used in households for non-drinking purposes such as toilet flushing and garden watering etc

  • How much of raw water is required to make 5 liters of good water?

    RO uses only 7-8 liters of water to make 5 liters of pure water. It recovers about 70-75% of the incoming water and only very small fraction of water around 20 % is rejected.

  • Can an RO purifier work on borewell water?

    Yes, an RO purifier will work on bore well water with limits of the water as specified. The raw water should not have Iron, Manganese or Oil.

  • How is RO water different from mineral water?

    Mineral Water – Water which is first made absolutely free from minerals or salts. Thereafter, minerals or salts are added in required proportion for taste and to meet the drinking water standards.

    RO Water can not be called mineral water because the salts or minerals are not dosed in it but are maintained by the rejection level of particular membrane.

  • Is RO water equivalent to distilled water?

    Distilled water is boiled, and the steam is then condensed for drinking water. Distilled water contains practically no minerals or dissolved solids, whereas RO water does contain trace amount of minerals and salts. Most people report RO as tasting better than distilled water, which can taste flat.

    Distillers use high electricity, whereas ROs work on mini low power booster pumps or on line pressure from the household plumbing.

  • How does it differ from my existing UV water purifier?

    Conventional water purifiers use a filter to separate out only the larger particles of dirt sediments from water.
    UV systems use an ultra violet lamp to deactivate the bacteria & viruses present in the water without physically removing them. It does not alter the taste of water. On the other hand, Reverse Osmosis not only removes suspended particles and microbiological organisms but also removes excessive salts, all harmful chemicals from raw tap water & gives crisp, crystal clear double safe germ free water.

  • Does a RO kill or remove all bacteria & viruses present in water?

    The RO membrane has a pore size (.0001 micron) much smaller than bacteria virus, pyrogen or the Cryptosporidium parasite. Hence it will remove all microorganisms.

  • Does RO remove any useful minerals? What health effects it will have?

    RO reduces most of the minerals from the water. RO removes all objectionable minerals and chemicals from water which are responsible for the bad taste, saltiness & metallic taste in water.

    The mineral content in water is much less than the mineral found in food. Minerals required by our body are derived mainly from food and less from water. For example, 250 ml or a glass of milk contains more minerals than 20 liters of drinking water. Hence low mineral content has no bearing on health; a simple example is the healthy civilization in Himalayan ranges, where the mineral content in drinking water is low

    Drinking water standards like USEPA, IS: 10500 have not set the lower limit of TDS (mineral salts) in water.

  • What kind of Service attention does this RO purifier need?

    When a purifier conditions or traps impurities, its filtering elements become a storehouse of dirt and disease causing organisms. Service is required for periodic washing, sanitizing and replacement of these filters. This ensures good life of the filtering elements and therefore consistent purification performance.

  • What factors should a buyer look for in a RO purifier?

    The buyer should look for following things :

    • Is the product tested and certified from an accredited laboratory for complete removal of all organisms, harmful chemicals ?
    • whether the product is certified for specific contaminant removal ?
    • Does the product water quality meet international drinking water standards like USEPA, WHO. ?

  • Why do you need an RO purifier at home or office?

    Municipal water treatment plants are miles away from our homes, treated water are likely gets contaminated during distribution.

    Chlorine introduced by treatment plants can form harmful disinfection by-products such as TTHMs (total trihalomethanes) and HAAs (haloacetic acids) in drinking water. These chemicals are known carcinogens or cancer causing..
    Hygiene of underground and overhead tanks of apartments and residential complexes is always a question.

    Ground water is invariably high in salts and harmful chemicals.
    Conventional water purifiers do not ensure complete removal of harmful chemical, excessive salts and all germs from drinking water.

    Timely supply of bottled water at homes and offices is based on reach of the distributor.

  • Can RO products be installed for any kind of water?

    RO products cannot be installed for any kind of water. Contaminants like Iron, Manganese and Oil can cause severe damage to RO membranes.

    The manufacturers of RO purifiers specify the maximum limit of contaminants (like heavy metals, organics, nitrates, chlorine, oil, hydrogen sulphide, silica, iron, manganese, etc.) in water. They also mention maximum limit of feed TDS (generally 1500 to 2000 ppm) to ensure adequate RO membrane life.

  • Do RO purifiers remove pesticides?

    RO purifiers reduce pesticide level in the water to certain extent. But a specially designed RO purifiers generally removes encountered pesticides in surface and ground waters.

  • Do RO purifiers require frequent maintenance?

    Maintenance needs of RO purifiers depend on the quality of incoming water. Turbidity, organic load & chlorine contents in the incoming water decide the life and efficiency of its cartridges. Calcium, magnesium or other salts tend to scale RO membranes which may require cleaning or replacement. Thus RO purifiers require planned maintenance schedules for replacements and cleaning.

  • What does RO purifier comprise of?

    Typical RO purifiers are multistage purification system. The first stage is sediment filter which reduces suspended particles. The second stage is carbon filter which reduces volatile organic matter, chlorine and other odour & taste causing compounds. Third stage is the membrane filtration using RO membrane. It is responsible for rejecting upto 98% of the total dissolved solids in the water. This is where purification takes place.

  • For how much of hardness is a softener required?

    Water with around 20 ppm hardness is termed as soft
    Water upto 60 ppm hardness slightly hard
    Water upto 120 ppm moderately hard (improves with a softener)
    Water upto 180 ppm hard (big improvements with softener)
    Water over 180 ppm hardness – very hard

  • How much of common salt is required for recharging the softener?

    Every time the softener stops giving soft water, the POU unit has to be filled with around 400 gms of pelletized recharging salt.

  • How much soft water will the product POU softener give?

    Based on the Hardness content in the raw water the output of the softener can be estimated, typically if inlet hardness is say 500 ppm as CaCo3 in Soft water output will be around 300 liters.

  • Where can the POU softener be connected at home?

    POU softeners can be connected to geysers, showers, wash sinks and washing machines.

  • How does the POU softener compare with other softeners in the market?

    Most softeners in the market are (POE) Point Of Entry products (whole house) hence large in size and high on cost. It has resin vessel, a brine tank which are floor mounted

    The compact wall mounted (POU) Point Of Use is meant for single point use such as geysers, washing machines, shower etc.

    The POU softener has a multiport valve .that directs the salty water to a separate drain line during recharging/regeneration process.. The product is user friendly, compact and low on cost.

  • Does the softener media needs to be replaced after softener stops giving soft water?

    Softener media is not replaced; it is recharged with pelleted recharging salt.

    In the process of softening the resin beads get exhausted with Calcium and Magnesium. resin can no longer soften the water. Then it is time to recharge the resin.

    During recharging process the salt chamber is filled with pelleted recharging salt. Water is allowed to pass in reverse direction for 30 minutes .

  • How does a water softener works?

    Its a very simple process in which the Calcium and Magnesium ions in the water are replaced with ions of salt (either Sodium or Potassium). These salts do not precipitate on pipes or react badly with soap and therefore eliminate the hard water problem.

    Water softeners contain Sodium rich ion exchanger resins that are designed to remove ions, mainly positively charged Calcium (Ca2+) and Magnesium (Mg2+) ions. This resin media exchanges the hardness minerals with its Sodium as the water passes through the media, thus making the water soft. This is called as softening process.

  • What is Mineral Water ?

    Mineral water is a water which comes from mountains , Rivers & fresh sources of water.

    Mineral water contains essential salts like Calcium , Magnesium & Sodium which are very important for our body to maintain its metabolism.

    Below are mentioned reasons why Mineral Water is different sources of water.

    What is mineral water ?

    According to FDA ( Food & Drug Administration ) the TDS ( Total Dissolve Solids ) of the Mineral water should be less than 250 PPM ( Parts per million ).

    As name represents Mineral Water contains high amount of dissolved salts like calcium , Magnesium , Sodium , Fluoride & Chloride.

    The Mineral water has a great flavor of taste as compared to other sources of water like Tap Water , Ground water etc. ( Source )

    Mineral Water is a form of water which contains proper amount of salts like sodium , Calcium , Chloride & Fluoride which are essential for our body . The mineral water has a TDS lower than 250 PPM ( parts per million ).

    A reverse osmosis system can generate mineral water by passing the Ground water / Tap water through a semi-permeable membrane.

    What are the health benefits of Mineral Water ?

    Because Mineral water contains proper amounts of salts required by our body , so it has major benefits :-

    Makes Our Bones Strong

    Proper amount of Calcium in Mineral Water keeps our bones healthy & Strong. Calcium is required by body at all the stages of our life to maintain bone development & maintenance.

    According to research on 255 postmenopausal women it is found that those who regularly drinks mineral water have higher bone density compared with who are drinking normal tap/ground water.

    The Sodium bicarbonate and magnesium found in mineral water also support bones and makes them stronger. ( Source 1 , Source 2 , Source 3 )

    Helps in Maintaining Blood Pressure

    According to a research it is proved that improper levels of sodium & Magnesium in Diet are major reason for high blood pressure, which leads to heart attack. ( Source 1, source 2, source 3 )

    A recent study suggests that drinking mineral water high in magnesium & calcium reduces high blood pressures.

    As Mineral Water is a good source of nutrients helps to lower the blood pressure levels , it is good for the peoples who are living at higher elevated levels.

    In one 4 weeks study on 70 peoples with having high blood pressure found that drinking 34 ounces of mineral water helped him to lower their high levels of the blood pressure.

    However, we have reviewed more than 20 researches & studies all are inconsistent . we need more research & studies which can prove the direct impact of mineral water on the blood pressure.

    Beneficial for heart’s health

    The properly carbonated mineral water helps our immune system to fight with heart diseases.

    Two researches on postmenopausal women found that drinking (1 – 1.5L ) of carbonated mineral water per day significantly reduced levels of Bad cholesterol & Increase the levels of good cholesterol.

    Another research states that higher levels of magnesium in mineral water reduces the chances of heart attack. ( Source )

    These researches doesn’t claim promising results , so we need more studies in future to determine how mineral water affects the heart health.

    Helps in constipation

    Mineral water rich in magnesium helps in treating constipation.

    According to a research magnesium helps in relaxing the intestines & makes stools softer which is easier to pass (Source).

    In a 6 weeks research on 106 People with functional constipation found that drinking 500ml of magnesium and sulfate-rich mineral water per day significantly improved bowel movement frequency and stool consistency (Source).

    That said, taking adequate amount of mineral fluids helps our body to improves digestion & proper bowl movement. (Source 1Source 2).

FAQs on recycled Water 16 questions
FAQs on Reverse Osmosis 25 questions
  • What is the life of reverse osmosis membrane?

    RO membrane will last for at least 3 years with proper operation and maintenance of RO plant and with proper pretreatment system.

  • What is tolerable limit for iron for RO system?

    Iron in feed water should be less than 0.3 ppm for trouble free and safe operation of RO system. Fouling will take place on RO membrane and it will reduce RO permeate flow, if iron is more than 0.3 ppm.

  • Does chlorine affect RO membrane?

    Yes, if chlorine is present in RO feed water, it will oxidize RO membrane and will increase the pore size of RO membrane. It will deteriorate RO permeate water quality.

    Hence chlorine should be Nil in RO feed water. Activated carbon filter and SMBS dosing system are provided in pretreatment to prevent chlorine from entering RO membrane.

  • What is feed water limiting condition for RO system?

    Following are the feed water limiting condition for RO system.

    a) Chlorine: Nil
    b) Suspended solids: < 1 ppm
    c) Turbidity: < 1 NTU
    d) SDI: < 4
    e) BOD and COD: Nil ( In some cases 10 ppm tolerable )
    f) Heavy metals: Nil
    g) Oil and grease: Nil
    h) pH (for cellulose acetate membrane): 4 – 6
    feed water limiting conditions
  • Is pH correction required for RO system?

    In some process application where neutral pH (pH 7) is desired, pH correction is required for RO permeate water. pH of RO permeate water is slightly acidic in nature. It is around 5.5 to 6.4.

    Normally pH correction is carried out by caustic or Soda ash solution or by using degasser system. Degasser system removes CO2 (Carbon dioxide) from water and raise pH of water up to 7 (neutral pH).

  • Can I use RO reject water for other applications?

    If RO reject TDS is 1000 ppm, we can use it for gardening purpose and toilet flushing purpose. RO reject water having TDS 1000 ppm to 2000 ppm can also be selectively used for plantation as some plants survive and grow on High TDS water.

  • What factors affect RO performance?

    Pressure, temperature, recovery and feed water salt concentration are the factors which mainly influence the RO performance.

  • Does RO system require cleaning?

    Yes, RO system needs cleaning frequently, to remove scaling and fouling from the membrane surface, to improve system performance.

  • What is MOC for RO membrane?

    Polyamide and Cellulose acetate are the MOC for RO membrane.

  • What does mean by ‘Flux ‘?

    The rate of Permeate water transported per unit membrane area is called ‘Flux’ of RO system.

  • What is meaning of ‘Reject water’?

    Concentrated high TDS water is rejected by membrane is called ‘Reject water’ of RO system.

  • What does it mean by ‘Permeate water’?

    Purified product water produced by membrane is called ‘Permeate water’ of RO system.

  • What is meaning of ‘Salt rejection‘?

    The percentage of Solute concentration removed from system feed water by the membrane is called ‘Salt rejection ‘. % Salt rejection = (1 – Salt Passage) X 100

  • What is meaning of ‘Salt Passage’?

    Theoretically no salt should pass through RO membrane. But no membrane is 100 % perfect. Hence some salt does pass through imperfections on the membrane.

    Passage of this salt is called ‘Salt Passage ‘. % Salt Passage = Permeate TDS / Feed TDS X 100

  • What does mean by ‘Recovery ‘of RO system

    ‘Recovery’ of RO system is defined as ratio of Permeate Flow to the Feed Flow.

    % Recovery = Permeate Flow / Feed Flow X 100
    For e.g. : If feed Flow is 100 m3/hr and Permeate Flow is 60 m3/hr Then Recovery of RO System is 60 %.
    Recovery = 60 m3/hr / 100 m3/hr X 100
    = 60 %.

  • How often should I change the filters in an RO system?

    The filters should be changed once a year. The membrane should be changed every 3 to 5 years depending on the TDS levels in the purified water.

  • Are RO systems difficult to install?


    The RO systems come complete with tubing, fittings and items required to install it. In some cases you may need to drill a new hole in your sink, or you can use an existing hole to install the RO faucet. Typically a plumber will take 20 minutes to read the installation instructions and 1 to 1-1/2 hours to do a professional installation, but many homeowners have installed these themselves.

  • Are bacteria a problem with reverse osmosis systems?

    Yes and no. We have tested many of our systems for total bacteria counts over the years and have not found higher levels after the systems unless the systems sat for several days in between uses.

    However, in some cases, bacteria can grow, particularly when the source water is high in bacteria and/or low in chlorine residual.

    We also have Ultra-Violet Sterilizer Systems that disinfect water after it leaves the filter system, insuring water low in bacteria. The manufacturers state in their warranty information that the RO systems are designed to be installed on water that is disinfected or does not have dangerous bacteria such as e.coli.

  • Will these systems remove parasites or cysts?

    Yes. The RO systems are certified for cyst removal.

  • Will these systems remove lead?

    Yes. Both the RO membrane and the carbon block filter will reduce the lead. Carbon block filters use a lead-specific filter media combined with the carbon to reduce lead.

  • Will RO’s remove hardness minerals or help cut down on scale build-up in coffee pots, etc.?

    Yes! Most water contains “total dissolved solids” (TDS), which is roughly the total inorganic mineral content of the water, and these are removed. The reverse osmosis membrane separates these dissolved solids, or salts and flushes them down the drain.

  • How do I know what is in my drinking water?

    If you are on city water, your local water must meet very strict Federal and State standards for purity. However, many areas use ground water (well water) high in minerals and salts.

    This can affect taste. All municipally treated water is chlorinated, and this can also affect taste and create odors in the water. If you are on a private well or spring, you should have your water tested. Contact AWS for specific recommendations.

  • What are the alternatives to RO?

    Distillation Method

    produces clean water by evaporating the water from the input and condensing the steam. It is highly energy-intensive and expensive unless you have a free source of waste heat. Distillation systems tend to be low capacity.

    Ion-exchange method

    systems work by exchanging cations such as calcium and magnesium for the cation on the resin, usually sodium, potassium or hydrogen. They also exchange anions like carbonate and sulfate for the anion on the resin, usually chloride or hydroxyl. These systems can be recharged and should be as the resins are very expensive. The recharging may be just a small annoyance (as with sodium chloride resins) or potentially hazardous (as with hydrogen/hydroxyl resins).

  • What is reverse osmosis (RO)?

    The other side of the coin is reverse osmosis. A difference in pressure is used to cause a difference in salt concentration.

    It is as though the pressure is being used to force the water molecules through the membrane while retaining the larger salt. Salt means any inorganic compound dissolved in water.

    When water is processed by reverse osmosis a large fraction of dissolved material is removed. The cleaner the input water the cleaner the output water will be. Conversely, if your input water is clean enough, you may not need an RO unit.

  • What is osmosis?

    Osmosis refers to the passage of water through a thin semipermeable membrane from the side with low salt concentration to the side with higher salt concentration.

    This can happen even when the water level is higher on the high salt side and the water must move against a pressure difference. The bottom line is that osmosis refers to a concentration difference manifesting itself as a pressure difference.

FAQs on Sewage Treatment 10 questions
  • Is the nutrient removal possible during domestic sewage treatment itself?

    Excess of nutrients is also not advisable and nutrients need to be removed. Nutrient removal is very much possible during wastewater treatment itself.

  • Will there be odor nuisance in surrounding areas of sewage treatment plants?

    Generally, odor problem occurs during biological treatment due to escape of gases like CH4, H2S, Ammonia, etc. but as our technologies are based on aerobic treatment, there will be no treat for odor nuisance in the surrounding areas.

  • Is it possible to reuse the treated domestic sewage for any other use?

    Yes, treated sewage water can be used for gardening, car washing, and toilet flushing system, etc. after proper polishing tertiary treatment.

  • Is there any requirement for nutrient addition during biological treatment?

    Nitrogen (N) and Phosphorous (P) are main ingredients of a cell are required for bacterial cell growth. Generally, sufficient amount of N and P are present in the domestic wastewater, so no requirement for nutrient addition. For industrial wastes, sometimes it becomes necessary.

  • What will be energy requirement for the treatment?

    For aerobic technologies, the energy requirement to treat 1 kg BOD/ hr is about 1.2- 1.4 HP.

  • How to choose appropriate technology, which suits to your needs?

    Choice of appropriate technology is mainly governed by effluent flow, area requirement, economical aspects and treated water applications, etc.

    Refer brochures for various technologies for more information.

  • What are various technologies available for biological treatment of sewage? Is it possible to meet the standards set for safe disposal of treated sewage?

    Both aerobic as well as anaerobic technologies can treat the sewage biologically by selecting suitable bacteria.

    Some of the aerobic technologies are :-

    Activated sludge process

    fluidised media reactor

    Membrane bioreactor

    trickling filter

  • How does the sewage treatment process work?

    Generally, domestic sewage consists of suspended solids, organics. Organic contributes to BOD.

    Treatment system focuses on removal of suspended solids, BOD, COD to the desired limit. System removes suspended solid through the sedimentation process, while BOD reduction takes place inside biological system.

    Typically, treatment scheme for domestic wastewater treatment consists of physicochemical treatment followed by biological system.

  • What is sullage?

    Out of the total domestic waste, the wastewater generated from kitchen and bathrooms is called as sullage. Sullage is much leaner in strength.

  • What is sewage? What is its typical quality?

    We use the water for various domestic applications such as drinking, cooling, bathing, toilets & washing. About 135-lpcd water consumption is considered by WHO. Generally 85-90% of water consumption becomes wastewater. Ideally, sewage is wastewater generated from toilets only but generally all domestic wastewater is collectively called sewage. Various organic as well as inorganic impurities get added into it. Typical wastewater characteristics of domestic sewage are as follows

    CharacteristicRange of values (gpcd)
    BOD5200 – 300
    COD500 – 600
    Total Organic carbon100 – 150
    Total Solids1200 – 1500
    Suspended Solids70-145
    Alkalinity as CaCO320-30
    Total Nitrogen as N6-12
    Total Phosphorus as P0.8-4.0

    However, the quality considered by Manual on sewerage and sewage treatment considers very high values, which normally are not encountered.

FAQs on Ultrafiltration 10 questions
  • what are hollow fiber membranes?

    Hollow fiber membranes: The “Romicon” fibers utilize an internally skinned polysulfone UF membrane.

    The typical fiber dimensions are as follows: Bore diameter: 1 mm ; Wall thickness: 0.5 mm ; O.D. = 2 mm.
    Pressurized feed passes through the fiber bore at comparatively high velocities. Reverse flow of permeate is also possible which allows back-flushing as a regular technique.

    The claim is made that back flushing provides a positive means of freeing the foulant from the membrane surface which increases the cleaning efficiency and extending run times and cartridge life.

    Limitations: Due to high packing density and correspondingly fine channel interstices, they are more susceptible to fouling, and more difficult to clean.

  • What are the membrane ratings?

    Membranes are rated in terms of molecular weight of the smallest molecule rejected by the membrane– called as Molecular weight cut-off (MWCO). MWCO ratings are given w.r.t.0.5 % solution of Poly-ethylene glycol (PEG).

    The typical ratings available are: 5000; 10,000; 30,000; 1,00,000; 5,00,000 etc. For example, for recycle of wastewater we use membranes with MWCO of 1,00,000.

    For pyrogen removal in production of Ultrapure water, membranes with MWCO of 10,000 are used whereas for bacteria removal membranes with MWCO = 85000 are used.

  • What type of membrane configurations are available?

    PS membranes are available in plate and frame, tubular, hollow fiber, and spiral-wound configurations.

  • What does a UF system consist of?

    Because the UF filters are expensive, they are not usually sized large enough to handle peak flows. This requires the system to have several components to allow the UF to produce water during times of no use and store it for later peak demands.

    The three basic components of the system are the UF filter (filter, housing, controls pre-filter and solenoid), storage tank with control float and re-pressurization pump. The re-pressurization pump delivers water from the storage tank to the house.

    The re-pressurization pump will cycle on and off to deliver the water to the water fixtures. When the water level in the storage tank drops below the float, the solenoid valve will open and send water through the UF filter to the storage tank.

  • What can this be used for?

    We use this process as an alternative to flocculation and filtration. This technique is not always an appropriate alternative to flocculation and filtration. On site testing and lab testing can be done to determine how successful either of these techniques will be for a particular application.

  • How does ultrafiltration membrane work?

    Untreated water is forced against a semi-permeable membrane. The membrane allows the water molecules to pass through and screens out the colloids much like a sieve. Excess water is used to wash the colloids off the surface and to a drain.

    Unlike most filtration, the sieve does not fill up with trapped material because the colloids are to large to fit into the opening of the sieve. A good analogy would be dumping a mixture of water and marbles (the colloids) over a window screen (the membrane).

    Most of the water would pass through the screen. The remaining water would help wash the marbles off the screen and would be sent to waste with the marbles. The screen would not become plugged because the marbles are too large to fit into the openings.

  • When do I use an Ultrafiltration system for water treatment?

    Ultrafiltration is a complimentary process to reverse osmosis where dissolved salts are not removed from water , which means there is no change in the chemical composition of the product water from an Ultrafiltration System. Large molecular weight organics (1000 daltons- 100,000 daltons) bacteria, colloids, viruses and other substances are removed from the water. This produces sparkling clear safe water.

    The three main applications in water treatment are

    • Bottled water production where feed water TDS is within limits, but clarity and disinfection is required
    • Pretreatment to reverse osmosis systems to enhance life of the Reverse Osmosis membranes and protect them form fouling. It is a single stage step process which eliminates, settling, sand filtration and polishing cartridge filtration
    • Domestic water purifier for producing sparkling, crystal clear, safe drinking water without electricity, chemicals and Ultraviolet rays
  • How Ultrafiltration (UF) Membranes are rated?

    UF are rated on their ability to remove certain sized molecules. The size of a molecule is roughly proportional to its weight, and therefore the MWCO specified for an UF indicates the minimum size (weight) of molecules that will be removed by a particular UF device.

  • Which materials are used for UF membranes?

    Poly-sulphone (PS) and it’s derivatives like poly-ether-sulphone (PES) are the widely used materials for UF. These materials can tolerate pH between 1 & 13, temperatures upto 75 deg C, and upto 50 ppm chlorine for long storage. These membranes can be cleaned with 0.1 % NaOCl solution.

  • What is Ultrafiltration (UF)?

    Ultrafiltration is a pressure driven membrane separation operation in which particulates, colloids, emulsified oils, and macromolecules are separated from a liquid feed stream upon passage through a porous semi-permeable membrane.

    The separation is based primarily on the size of the species in the liquid relative to the size of the membrane pores. UF membranes can provide filtration in the 0.0015 to 0.1 micron (1000 MW to colloidal) range.

    As a consequence of high molecular weight of solutes, the osmotic pressures of the solutes are usually low. Thus the operating pressures of UF range from 0.5 to 7 bar only.

FAQs on wastewater treatment 10 questions
  • What is anaerobic wastewater treatment?

    Anaerobic wastewater treatment does not require oxygen for assimilation of organic matter from wastewater. This means, that bacteria that are NOT oxygen dependent while converting the contaminants in the water.

    Anaerobic bacteria can only convert when oxygen levels are low, because they use other sorts of substances to perform chemical conversion. Anaerobic bacteria do not just develop carbon dioxide and water during conversion, but also methane gas.

    The methane gas produced can be used as a fuel in boilers or in gas/dual fuel engines. After anaerobic conversion usually aerobic bacteria (bacteria that do use oxygen) still need to finish the process, because the water is not clean enough yet.

  • What is aerobic wastewater treatment?

    Aerobic wastewater treatment is the process where bacteria requires oxygen for their respiration while oxidizing or consuming organic matter present in the wastewater.

    Aerobic bacteria can only convert organic compounds when plenty of oxygen is present, because they need it to perform any kind of chemical conversion. Usually the products they convert the contaminants to are carbon dioxide and water.

  • What is a wastewater treatment system?

    Wastewater treatment is the process of removing contaminants from wastewater and household sewage, both runoffs (effluents), domestic, commercial and institutional. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants.

    Its objective is to produce an environmentally safe fluid waste stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or reuse (usually as farm fertilizer).

  • Why is it necessary to treat wastewater?

    Proper treatment of wastewater reduces health risks to humans, animals and prevents surface and groundwater contamination. Wastewater treatment helps to reuse the waste water and reduces the consumption of fresh water.

  • Where does wastewater come from?

    Waste water comes from sewage which includes black water (human waste) and grey water (kitchen and laundry waste), septic tank discharge, industrial waste which includes effluent and process water.

    Agricultural practices also produce waste water by contaminating water with pesticides and fertilizers

  • What is Eutrophication? How it can be prevented?

    Increase in the concentration of phosphorus, nitrogen, and other plant nutrients in an aquatic ecosystem such as a lake is called eutrophication. This rise is nutrient level results in an accelerated life cycle of water plants like algae, water hyacinth, etc.

    Vegetative cover restricts entry of light and oxygen in the water. Moreover the degrading debris uses up all available dissolved oxygen in water rendering the water lifeless. Wastewater should be treated for removal of phosphorus and nitrates by various physical chemical and biological methods.

    Effective technologies are available in removal of nutrients along with BOD and COD. Conventional methods of separate nitrification and denitrification can also be adopted but with increased cost and area.

  • How do we detect water pollution?

    Water is polluted by different contaminants and it can be detected by analyzing water samples in laboratory. Titration test is to detect hardness, dissolve oxygen, carbon dioxide and alkalinity.

    Colorimetric tests are performed to check PH, Phosphate, silica, ammonia and Sulfides. Heavy metal limit test is to determine the level of heavy metals.

  • Where does water pollution come from?

    The sources of water pollution are categorized as direct and indirect contaminant sources. Direct sources directly discharge contaminants into surface water which includes waste water from factories and sewage from housing colonies.

    Indirect sources include contaminants that enter the water supply from soil/groundwater systems and from the atmosphere via rain water. Soil and ground waters contain residue of agricultural practices (fertilizers, pesticides, etc.) and improperly disposed of industrial wastes.

    Atmospheric contaminants are also derived from human practices (such as gaseous emissions from automobiles, factories and even bakeries).

  • What are the major water pollutants?

    The large number of water pollutants may be broadly classified under the following categories:

    1. Inorganic pollutants

    2. Organic pollutants

    3. Thermal pollutants

    4. Radioactive pollutants

    5. Sediments

    6. Infectious agents

    7. Plant nutrients

    Inorganic pollutants

    Inorganic chemical pollutants are naturally found in the environment but due to human development these pollutants are often concentrated and released into the environment .The primary inorganic pollutants of concern are cadmium, copper, lead, zinc, nitrogen, nitrate, nitrite, ammonia, phosphorous, and phosphate


    Industrial effluent is the major source of Inorganic pollutants cause. E.g. sulfur dioxide from power plants, Ammonia from food processing waste and chemical waster from industrial byproducts. Agricultural fertilizers and surface runoffs are other sources of Inorganic pollutants

    Harmful effects:

    • Can kill the fish and other aquatic animals
    • Interfere with suitability of water for drinking and industrial use
    • Toxic pollutants tend concentrate in food chains
    • Degrade the soil microbial activity
    • Loss of vigilance ability
    • Loss of hand to eye coordination
    • NO2 gas can cause coughing, breathlessness, irritation of upper airways, bronco spasms, nauseas and vomiting

    Organic pollutants

    Organic pollutants are basically compounds which may be degraded by micro organisms. It usually uses up the available oxygen in the process of degradation. The optimum DO in natural water is 4-6 ppm and hence organic pollutants like sewage waste, oils etc must be removed to keep water free from such pollutants.

    Thermal pollutants

    Heated water is discharged as industrial effluents. In order to maintain the ecological balance temperature needs to be equalized with the receiving water body. This is an important criterion as increased temperature lowers dissolved DO in water.

    Radioactive pollutants

    Uranium and thorium wastes from mining, refining and its various industrial applications contribute to radioactive wastes. Nuclear power plants, medical and scientific research use are areas where such wastes may be created.


    Erosion removes soil and minerals from crop lands, forests, residential and corporate communities and carries it as sediment. Sediments represent the most extensive pollutants of surface water.

    Bottom sediments are important source of inorganic and organic matter in streams, fresh water, estuaries and oceans. Sediments are also repositories for trace metals such as Co, Cr, Cu, Mn, Mo, Ni, etc.

    Infectious agents

    Wastewater discharged from municipalities; sanatoria, tanning etc. may contain decease producing micro-organisms.

    Plant nutrients

    Growth stimulating plant nutrients include like nitrogen and phosphorous add to the BOD of the water. Presence of nutrients encourages algal growth, which decreases DO levels, and creates problems in treatments.

  • What is water pollution?

    The term water pollution, in general can be defined as any alteration in physical, chemical or biological properties of water by discharge of any sewage or industrial waste or of any liquid, gaseous or solid substances into water as may, or is likely to create nuisance or render such water harmful or injurious to public health of safety, or to domestic, commercial, industrial agricultural or other legitimate uses, or animal life and health.

FAQs on water quality and drinking water 12 questions
  • What dangers can be there in drinking water other than microorganisms?

    Besides microorganisms, there are several problems that can affect the quality of drinking water. Fluoride is very common element, found in earth’s crust. Fluoride also enters in the aquatic system in the dissolved form through industrial discharge form through aluminium industries, phosphite industries, coal plants, etc.

    Higher concentration in drinking water can affect the health adversely. The World Health Organization (WHO) guideline for fluoride is 1.5 mg/liter in drinking water. As per IS 10500 standard the desirable limit for fluoride is 1 ppm and permissible limit is 1.5 ppm in drinking water. Ion Exchange has fluoride removal resin and activated alumina based Fluoride Removal Units.

    Arsenic contamination is a serious problem found in ground water in Eastern part of India (West Bengal) & Bangladesh. The normal concentration of arsenic is around 0.1 to 1.5 ppm. In most of the areas, concentration varies from 0.2 to 1.0 ppm. However permissible limits for drinking purpose is less than 50 ppb. The excess intake of arsenic leads to skin diseases like hyper pigmentation, keratoses melanomas that disfigure the skin like in leprosy. Ion Exchange has developed Arsenic Removal Units (ATU) for removing arsenic from drinking water.

    Nitrate in drinking water can cause cyanosis, a reduction of the oxygen carrying capacity of the blood. This is particularly dangerous to infants under six months of age.

    Lead can enter the water supply as it leaches from copper pipelines. As the water streams through the pipes, small amounts of lead will dissolve in the water, so that it becomes contaminated. Lead is a toxic substance that can be quickly absorbed in the human systems, particularly those of small children. It causes lead poisoning.

    Iron is another common pollutant found in nature. Water percolating through soil and rocks, dissolves iron and subsequently enter to ground water supplies. High concentration of Iron cause reddish brown stains on laundry and household fixtures. Sometimes it may clog water distribution pipes. High level of iron can impart a bitter sweet or metallic taste to drinking water. The drinking water standard for iron is 0.3 ppm as per USEPA 2012 and as per IS 2012

    Chorine in municipal water when combined with organics, forms Trihalomethanes (THM), which are carcinogenic Volatile organic compounds (VOC’s) also are cancer causing contaminants.

  • Is boiling water enough for safe drinking?

    Boiling kills almost all pathogens from water. It is safe when only microbial contaminants are of concern. It effectively kills Giardia cysts. Water disinfected by boiling can conform to IS 10500 drinking water standards for bacteriological quality. It does not remove bad taste, odour, colour, dissolved salts and chemical contaminants from water.

  • What are the diseases caused by various bacteria and viruses?

    Waterborne diseases

    Hepatitis virusJaundice
    RotavirusGastroenteritis Dysentery
    Vibrio choleraeCholera
    Shigella sppDysentery
  • How do pathogens enter drinking water?

    The pathogens enter drinking water through faulty municipal pipeline, unprotected and unhygienic open wells & human and animal waste. They are the carriers of microorganisms that find entry in to drinking water sources

  • What are pathogens? How they can be removed?

    Pathogens are disease causing microorganisms

    These include Protozoa, Bacteria and Viruses.

    The two most common protozoa pathogens are Giardia lamblia (Giardia) and Cryptosporidium (Crypto). Protozoa are responsible for many cases of amoebic dysentery. Protozoa cysts range is size from 2 to 15 µm (a micron is one millionth of a meter), but can squeeze through smaller openings. In order to insure cyst filtration, filters with absolute pore size of 1µm or less should be used.

    Bacteria are single celled microorganisms, which lack well defined nuclear membranes and other specialized functional cell parts. They are so small, that humans cannot visualize them. We can only see them through microscopes, by which the cells are greatly enlarged. Bacteria are smaller than protozoa and are responsible for many diseases such as typhoid fever, cholera, diarrhea, and dysentery. Bacteria range in size from 0.2 to 0.6 µm, and a 0.2 µm filter is necessary to filter these

    Waterborne pathogenic viruses range in size from 0.020-0.030 µm, and are too small to be filtered out by a mechanical filter. All waterborne enteric viruses affecting humans occur solely in humans,

    There are various methods of removing microorganisms. These include boiling, Chlorination systems, Iodine based resin systems, RO systems, etc.

  • How to make water soft?

    Water can be made soft by removing the ions that cause the water to be hard, in most cases calcium and magnesium ions. Iron ions may also be removed during softening. A water softener is often used to remove this hardness from water.

  • What is hard water?

    Water is hard when it contains minerals such as magnesium and calcium. If you have hard water, you may see staining on your sinks, tubs, showers and clothing; and build-up on your glassware.

    Hard water can produce a rock-like scale that builds up in pipes, dishwashers, water heaters, ice machines and other appliances. This scale can also reduce water flow and clog valves and vents to create maintenance problems and reduce service life. You may also notice less lather from your shampoo and soap.

  • Isn’t my municipal water treated?

    Many municipalities treat water with clarification, filtration and chlorine to kill bacteria. Their goal is to only meet minimum drinking water requirements. Many times, water gets re-contaminated during distribution through long pipe line net work.

    With chlorine, water may get disinfected but there may be other chemical impurities accidentally seeping in to municipal water pipelines which could be industrial chemical contaminants like arsenic, fluoride, mercury, pesticides, volatile organic compounds, etc., which cannot be removed by just chlorination, sophisticated treatment technologies like Reverse osmosis would be required to remove these contaminants

    To eliminate these contamination problems, Point of use home water treatment system is often necessary.

  • Why does tap water often smell like chlorine?

    To remove bacteria from drinking water and to protect it from re-contamination during distribution, municipal treatment plants add chlorine during treatment. Chlorine is a very effective disinfectant, which is used to kill any harmful bacteria that might be present in the water source.

    Generally, around 0.2 mg/l of free residual chlorine is maintained for complete disinfection. Although 0.2 ppm is the minimum required level at Point of use, presence of 1 ppm and above excess chlorine gives rise to smell in tap water.

  • How much water does a person use each day?

    In India, the average water use is around 145 litres a person each day with the following break up.

    Water usage Quantity (lpcd)

    Drinking             3

    Bathing            30

    Toilets/Flushing 45

    Laundry            30

    Kitchen/ Dish washes 22

    Leakages 15

    Total 145

  • Isn’t bottled water better than tap water?

    Water from tap can be turbid, may contain high levels of Ca, Mg, and many other microbial / chemical contaminants where as bottled water is a processed water by UF, RO or silver ionization,

    so generally if the bottled water company is certified by BIS (Bureau of Indian Standards) and product water is meeting the specs of packaged drinking water IS 14543, bottled water is better than tap water.

  • What are drinking water standards?

    Drinking water standards for packaged and non packaged water are as follow:

    SR NO.IMPURITYIS Desirable limit as per IS 10500: 2012USEPA Maximum Contaminant level as per EPA: 2012WHO Guideline value as per Vol.1, Recommenda- tions 2011IS DesirableLimit as per IS 14543 :2004
    1Colour Hazen units5NA15 true colour units2
    2OdourUnobjectionable3 threshold odour numberNot offensiveAgreeable
    3TasteAgreeableNANot offensiveAgreeable
    4Turbidity, NTU5552
    5Dissolved solids, mg/l5005001000500
    6Total hardness Calcium mg/l Magnesium mg/l30075–NA—-500 (as CaCo3)—-NA7530
    7PH value6.5 – 8.56.5 – 8.56.5 – 8.56.5 – 8.5
    8Copper mg/l0.
    9Iron mg/l0.
    10Manganese, mg/l0.
    11Chlorides, mg/l250250250200
    12Sulphates, mg/l200250400200
    13Nitrates, mg/l45101045
    14Fluorides, mg/l1.
    15Phenolic compounds, mg/l0.0010.0010.001Absent
    16Mercury, mg/l0.0010.0020.0010.001
    17Cadmium, mg/l0.010.0050.0030.01
    18Selenium, mg/l0.
    19Arsenic, mg/l0.
    20Cyanide, mg/l0.050.20.1Absent
    21Lead, mg/l0.050.0150.010.01
    22Zinc, mg/l5535
    23Anionic detergents, mg/l0.20.20.2
    24Total pesticides, mg/lNIL0.00050.00050.0005
    25Total bacterial count, CFU/ mlNot more than 500100/ml at 200C20/ml at 370C
    26Total coliform per 100 ml (including Fecal coliform & E-coli)AbsentAbsentAbsentAbsent
    27Viruses (Enteric)AbsentAbsentAbsentAbsent
FAQs on water treatment 12 questions
  • Why do you need internal treatment?

    Internal treatment of water in a boiler is essential to chemically adjust or balance the water to avoid scale formation, inhibit corrosion and prevent contamination of steam. Internal treatment is essential for most boilers because impurities are bound to enter the system either through the feed water or condensate return, no matter how sophisticated the external programme may be.

    Internal treatment of boiler water is complementary to the external treatment of boiler feed make up. Similarly internal treatment of the water used in a cooling system is essential to prevent scale formation, corrosion and fouling of the system. 

  • What are the treatment methods employed in conditioning water?

    The treatment methods employed in conditioning of water may be grouped into two broad categories namely:

    A. External treatment, and
    B. Internal treatment

    External treatment involves the passage of water through equipment such as clarifiers, filters and ion exchange equipment like softeners and demineralizers. The treatment is external to the point of use.
    Internal treatment on the other hand is the addition of chemicals like scale and corrosion inhibitors to the water at the point of use to make it more suitable for the proposed application.

    External treatment is sometimes referred to as primary purification or preliminary treatment while internal treatment is called post treatment or secondary treatment.

    In external treatment coagulation, clarification and filtration are same of the processes employed to remove suspended solids.

    Ion exchange processes are employed for removal of dissolved impurities and equipment like degassers and deaerators are employed to remove dissolved.
    In internal treatment, scale and corrosion control are achieved by dosing suitable chemicals to inhibit and control formation of scales. In cooling water treatment biocides are employed to minimize bacterial growth. In boiler feed water treatment chemicals like sodium sulfite and hydrazine are dosed to prevent corrosion due to dissolved oxygen. 

  • How do surface waters differ from ground waters in terms of the impurities present in them?

    A. Surface waters contain varying amounts of suspended solids consisting mainly of clay, silt-high during monsoon and low during summer.
    Most surface waters contain organic compounds which are the products of decay of natural vegetable matter such as leaves, grass etc. These compounds are high molecular weight carboxylic acids and are collectively called ‘organic matter’. The elimination 0f organic matter is important particularly in demineralization as they affect the performance of the anion exchangers used in the DM plant. Surface waters also contain floating micro-organisms such as algae.
    These waters are saturated with dissolved oxygen but contain comparatively lower concentrations of carbon dioxide. Surface waters however do not contain significant quantities of dissolved heavy metals like iron and manganese as they are often saturated with oxygen.
    Surface waters contain relatively lower concentration of dissolved solids.

    B. Ground waters are practically free from suspended solids as they get filtered when the water percolates through the strata.
    These waters do not as a general rule contain organic matter or floating microorganisms.
    Ground waters may contain very low amounts of oxygen but very high amounts of carbon dioxide.
    They may also include dissolved heavy metals like iron and manganese. Presence of iron causes the typical ‘red’ water and presence of manganese gives rise to the typical ‘black’ water.
    Ground waters have relatively higher concentration of dissolved solids and most tube well waters are high 1n dissolved solids often exceeding 1000 ppm.  

  • What are the objectives in water conditioning?

    The main objective in water conditioning is the removal of reduction of undesirable impurities present in the water and introduction of certain desirable properties Which render the water non-scaling, non-corrosive and non-fouling.

    Use of untreated water in boilers results in scale and deposit formation, corrosion and carryover. In cooling water systems, use of untreated water results in problems like scale and deposits, corrosion and fouling.

    The net result is loss in system efficiency, damage to equipment and plant outages resulting in loss of production.

    Similarly in process applications, presence of iron in water causes discoloration if used in the textile industry. Use of hard water for bleaching and dyeing results in appearance of ‘patches’ in the fabric. Use of ‘ultra pure’ water is essential in the semi-conductor industry to ensure production of quality components.
    The above examples show the importance of water conditioning for any industry. 

  • What is industrial water conditioning?

    Industrial water conditioning may be defined as the application of processes and methods by which water is treated to make it suitable for the various applications such as boiler feed, cooling etc. 

  • What are the principal uses of water in industry?

    Water required for cooling and condensing purposes constitutes well over 90%of the total quantity of water used in industry. Boiler feed makeup is the next important use. Other uses include water for process applications such as bleaching and dyeing in the textile industry, water for food canning, and water for rinsing of electronic components.
    Water is also used in the industry for drinking and sanitation and fire fighting. 

  • What are the sources of water for industrial application?

    The main sources of water for industrial applications are those from surface and ground waters. Surface waters include river water arid water from lakes and ponds. Ground waters include waters drawn from shallow or deep tube wells.

    The essential difference between the two sources is that while ground waters, because of percolation through the strata are normally free from suspended particles, surface waters contain varying amounts of suspended solids and turbidity. 

  • What are total dissolved solids (TDS) and how to remove them from water?

    The TDS indicates the total content of dissolved solids in water. It represents all the charged ions, cations and anions, as well as the uncharged and molecular species. The TDS represents the cations which are mainly calcium, magnesium and sodium; the anions which are mainly bicarbonate, chloride and sulphate and species such as silica. The value of TDS can be determined by a measurement of conductivity as there are TDS-conductivity relationships. The individual ions and species in water can also be determined separately.

    There are various methods of removal of TDS from water and they include ion exchange process, reverse osmosis, electro dialysis, distillation, evaporation, etc.

  • What are the equipments used for removal of turbidity and suspended solids?

    If turbidity is too high (above 50 NTU), it is recommended to use clarifiers. For lower turbidity values (below 50 NTU), filters can be used. But continuous filters like Dynasand Filter can be used upto 150 NTU turbidity.

    Membrane systems such as Ultrafiltration System are used where high turbidity and suspended solids removals are required.

  • How turbidity and suspended solids are removed in water treatment?

    Suspended Solids refers to all matter suspended in water. Turbidity indicates the presence of colloidal matter in water. While suspended solids do make a water sample turbid, there is no quantifiable relationship between turbidity and suspended solids. The coagulation-flocculation processes facilitate the removal of suspended solids, turbidity and colloids.

    Suspended solids settle rapidly in water. Clay-like material of the size of a few microns take time to settle; while colloids which refer to particle size in the sub-micron range cannot settle naturally and so the process of coagulation-flocculation brings about the settling of these substances to effect their removal.

    In raw water, colloids invariably carry a negative charge (ionization of peripheral chemical groups such as hydroxyl, carboxyl, phosphates, sulphates, etc.). The neutralization of this surface charge is termed as destabilization of the colloid. The destabilization is achieved through a covalent reaction between these groups and the polyvalent metallic ions of the coagulant.

    Coagulation is therefore the destabilization of colloidal particles brought about by the addition of a chemical reagent known as coagulant. Flocculation is the agglomeration of destabilized particles into microfloc and later into bulky floc which can be settled. The introduction of another reagent called a flocculant

  • What are various contaminants in water?

    Contaminants in water depend upon the source of water and its location. Common contaminants are as follow:

    Turbidity and suspended solids

    Dissolved solids






  • What is turbidity and how it is removed?

    Turbidity in water is due to presence of finely divided particles of colloidal dimension such as clay, algae etc. These particles cause haziness in water  due to scattering of light by these particles. It is measured in terms of Nephelometric Turbidity units (NTU). 

    Turbidity is undesirable for 3 reasons:

    1. Aesthetic considerations.

    2. Solids may contain heavy metals, pathogens or other contaminants.

    3. Turbidity decreases the effectiveness of water treatment techniques by shielding pathogens from chemical or thermal damage, or in the case of UV treatment, absorbing the UV light itself.

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