Reducing of Pb2+ and Cd2+ from Well Water with RO Plants

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Our goal is to decrease the concentration of Pb2+ and Cd2+ from well water with RO plants.

Feed water analysis for Cd2+ is 0.02 ppm and for Pb2+ is 0.1 ppm.

Can the concentration of these heavy metals be reduced to below 0.01 and 0.003 ppm for Pb2+ and Cd2+, respectively?

Should the RO system be designed in a specific way?

What is a cost-effective method, if it is necessary, for pre-treatment?

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11 Answers

  1. hello Mr.Ahmadi,

    Hope am not too late.But I wish to offer you my patent  no.IN 201811011885 titled BIOREMEDIATION SYSTEMS AND METHODS FOR REMOVING DAMAGING HEAVY METALS FROM INDUSTRIAL EFFLUENTS as a Inventor. The idea is that it uses the technique of Bioremediation and shall remove all heavy metals to zero.Is a continous process and does not require electricity or any kind of equipments in particular. Both these heavy metals can be reduced to being absent forget about a certain limit..Plus the technique gives you the liberty to use the heavy metals elsewhere. Please write back to know more.

    Regards

    Suhasini

  2. hello Mr.Ahmadi,

    Hope am not too late.But I wish to offer you my patent  no.IN 201811011885 titled BIOREMEDIATION SYSTEMS AND METHODS FOR REMOVING DAMAGING HEAVY METALS FROM INDUSTRIAL EFFLUENTS as a Inventor. The idea is that it uses the technique of Bioremediation and shall remove all heavy metals to zero.Is a continous process and does not require electricity or any kind of equipments in particular. Both these heavy metals can be reduced to being absent forget about a certain limit..Plus the technique gives you the liberty to use the heavy metals elsewhere. Please write back to know more.

    Regards

    Suhasini

  4. For pre-treatment of water from Pb2 + and Cd2 +, try using a sand filter, replacing the sand with crushed glass.

  5. Good Morning Mr. Ahmadi,

    Mr. Manickam's response is correct.   RO can achieve 99+% rejection for lead and cadmium.  RODI will achieve 100% removal.

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  6. Not a water expert but adding a tiny amount of sodium sulfide will precipitate out all these metals. Running the water through limonite or hematite gravel will remove the sulfide ions & colloids before RO. Smell/taste test after RO will ensure that water is drinkable.

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  8. First  stop using a 1950s technology.  Use something like ours.  100% thruput.  No reject water and removal of all contaminated to a desired or required level.  At a cost less than RO. 32 stages of organic filtration with a electrical process and ion exchange.  All in the same system

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  9. At 80% recovery on the RO, you would require 95% rejection to reduce the Cd to that level and 97.5% rejection for the Pb.  Contact a membrane manufacturer and see if they think that is possible at the feed concentrations of 0.02 and 0.1.  For ions with a +2 valance you should get over 99.5%, but that is at much higher feed concentrations.  Rejection % goes down as concentration goes down.  I think an RO will probably do it.

    As for pretreatment, it all depends on feed water.  Well water does not have the high TSS levels of surface water, so you may be fine with just cartridge filtration.  What is the TSS or SDI?

    You will also need something to control scale.  If the flow is small and the hardness not too high, you could consider a softener.  The larger the flow and higher the hardness, you would want to look at using an antiscalant.

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  10. The regulation for cadmium became effective in 1992. Between 1993 and 1995, EPA required your water supplier to collect water samples once and analyze them to find out if cadmium is present above 5 ppb. If it is present above this level, the system must continue to monitor this contaminant every 3 months.

    You can also opt for chelation treatment but treated water will have traces of chelating compound . To counter this consumer must take few supplements.

    If contaminant levels are found to be consistently above the MCL, your water supplier must take steps to reduce the amount of cadmium so that it is consistently below that level. The following treatment methods have been approved by EPA for removing cadmium: Coagulation/Filtration, Ion Exchange, Lime Softening, Reverse Osmosis.