Chlorine Dose for Industrial Water

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How can I calculate the right dose of chlorine in an industrial water tank? This water is treated to become drinking water. 

Is there a formula in which I can enter my parameters?

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17 Answers

  1. As you already know the chlorine concentration decays within the space and time. According to Safe Drinking Water Act the concentration in all user demand point(i.e. taps) should be in between 0.2-4.0 mg/L . In order to analyse your system you can use EPANET program by entering your tank volume and settşng a mass booster type in the outlet of your tank. Then after your simulation you could be obtained the concentration at any time from a distance of pipe you want to satşsfy the limits. 

  2. Muhammed,

    There ahs been much good discussion below on determining the chlorine dosage.  I have a few closing thoughts:

    1.  The water needs to be free of suspended solids (i.e., filtered) for chlorination to work.  Bacteria can hid inside of a solid and not be impacted by the chlorine outside the solid.

    2.  Add chlorine until you hold a residual and continue checking that the residual is maintained.

    3.  What else is in the water?  If this is an industrial source, is there any other chemicals in the water?  Heavy metals?  Is the tank suitable for storing drinking water?

    4.  After applying the chlorine, you must mix it in and hold for the proper CT time (the time (T) needed varies depending on the concentration [C]).  One to two hours is typically adequate.

    These are just my opinions.  I recommend you hire a qualified water treatment engineer to design your system.

    Good luck and be careful.

  3. Chlorine readily combines with chemicals dissolved in water, microorganisms, small animals, plant material, tastes, odors, and colors. These components "use up" chlorine and comprise the chlorine demand of the treatment system. It is important to add sufficient chlorine to the water to meet the chlorine demand and provide residual disinfection.

     

    The chlorine that does not combine with other components in the water is free (residual) chlorine, and the breakpoint is the point at which free chlorine is available for continuous disinfection. An ideal system supplies free chlorine at a concentration of 0.3-0.5 mg/l. Simple test kits, most commonly the DPD colorimetric test kit (so called because diethyl phenylene diamine produces the color reaction), are available for testing breakpoint and chlorine residual in private systems. The kit must test free chlorine, not total chlorine.

    To calculate contact time, one should use the highest pH and lowest water temperature expected. For example, if the highest pH anticipated is 7.5 and the lowest water temperature is 42 °F, the "K" value (from the table below) to use in the formula is 15. Therefore, a chlorine residual of 0.5 mg/l necessitates 30 minutes contact time. A residual of 0.3 mg/l requires 50 minutes contact time for adequate disinfection.

     

    Chlorination levels

    If a system does not allow adequate contact time with normal dosages of chlorine, superchlorination followed by dechlorination (chlorine removal) may be necessary.

     

    Superchlorination provides a chlorine residual of 3.0-5.0 mg/l, 10 times the recommended minimum breakpoint chlorine concentration. Retention time for superchlorination is approximately 5 minutes. Activated carbon filtration removes the high chlorine residual.

     

    Shock chlorination is recommended whenever a well is new, repaired, or found to be contaminated. This treatment introduces high levels of chlorine to the water. Unlike superchlorination, shock chlorination is a "one time only" occurrence, and chlorine is depleted as water flows through the system; activated carbon treatment is not required. If bacteriological problems persist following shock chlorination, the system should be evaluated.

     

     

    http://www.water-research.net/shockwelldisinfection.htm

  5. Chlorine dose is decided based on the chlorine demand of water. So find out chlorine demand and fixed the dose 0.5 mg above the chlorine demand figure

  13. Hi Muhammad,

    I have learnt from my field experience that any formula in this case may only be a guide. I suggest you analyze for the Physicochemical and bacteriological parameters of the industrial water as first approach. The value of the residual chlorine ( if any) and other parameters will guide you in appropriate treatment to make the industrial water potable. You can try using an efficacy test approach, that is, using pilot trials to determine the amount of Chlorine or Sodium Hypochlorite that disinfects the industrial water to acceptable and permissible drinking water quality standards in your location and in accordance with WHO guidelines for drinking water.

    The value or amount of Chlorine or Sodium Hypochlorite that gives you the efficacy could be used as your basis for chlorine or Sodium Hypochlorite dosage. You can set you disinfectant dosing pump to that value in relation to time and quantity of water being treated as a scale up from your pilot value and confirm the output (treated water for drinking by usual analysis).

    Please note that using this method means that the quality and quantity of industrial water generated/treated must be constant, which in most cases are not. So you might need to be performing the pilot trials for each batch of industrial water generated, it might also contain other contaminants you have to remove by physical or chemical treatments. Converting industrial water to drinking water needs painstaking approach(es).

    Regards

    Justin.

  14. The basic answer is that you need to cover the chlorine required for the disinfection plus the chlorine demand of the water. This would be for simplicity and safety 10 times the ammonia content .

    I think that the phrasing of the question raise

  15. One means to estimate required chlorine to achieve drinking water disinfection is to execute a chlorine demand test.  Obtain a sample of the water to be treated, then titration that sample with a known concentration of chlorine while measuring the residual chlorine.  This method provides an estimate of the dosage required for the water and confirmation of residual chlorine would then be recommended prior to the water being deployed in a potable system.

  16. Bonjour 

    Les eaux usées domestiques contiennent des pollutions dissoutes. Il en va de même dans les eaux usées industrielles même c'est beaucoup plus grave car ces eaux usées contiennent énormément de chimique dissout. Ajouter du Chlore ne fera qu'empirer la pollution et rendre cete eau potable frole le crime contre l'humanité.

    Aucun dispositif ou système est de nos jours en mesure de rendre une eau potable en purifiant l'eau de la pollution dissoute. Faire de l'eau morte, inerte, vide ne doit pas être considéré comme une eau potable, simplement une alternative. l'eau potable se fabrique en temps/année et elle contient des éléments vitales pour le développement de l'homme.  

     

    Hello domestic wastewater contain dissolved impurities. It similarly in wastewater industry even it is more serious because these wastewaters contain a lot of chemical dissolved. Add chlorine will make that worse pollution and make cete water drinking close to crime against humanity. No device or system is today able to make drinking water by purifying the water of dissolved pollution. Make dead, lifeless, empty water should not be considered to be drinking water, just an alternative. drinking water is made in time/year and it contains elements that are vital for human development.  

  17. If intended for human consumption the residual chlorine should be monitored continously. If your instrument (chlorine analyser) has a PID signal outlet 4-20 mA, you could receive this signal by an appropriate connected dosing pump in order to regulate the chlorine dosage at the exact set point (0.2 ppm, usually, depending of the piping length).

    This way the chlorine dosage will be the perfect one, non dependant from chlorine concentration (it decomposes during time), neither from chlorine consumption due to water contaminants.

    Whatever estimation you will make for this specific dosage, the chlorine solution is unstable (so, you must always analyse the real concentration) and chlorine demand /consumption is dependant from water quality, which is generally not stable.

    Regards !

    1 Comment

    1. Thank you all for answering my query, I beleive there are my conutry local standard which describe residual chlorine concentration at source and end point, so I think it is concluded that one can set dosing as per required concentration which has to be achieved.

      Anyone can tell me how to convert from mA to PPM ?