Chlorine Removal Sodium Metabisulfite (SMBS) & Active Carbon

Hello,

We need to use SMBS and carbon filter together to remove chlorine,

Which stage comes first, what would you recommend?

Thanks.

Taxonomy

• Carbon Filtering
• Chlorine Dioxide
• Chlorination
• Chlorine Dioxide Treatment

11 Answers

1. Once again---the oxidation reduction chemistry of SO2 and bisulfite with chlorine is very complete, so you would not need GAC for chlorine removal. Who told you that you need it? Maybe you need a different consulting engineer? Also, adding ammonia to produce a small amount of chloramine is probably your best choice, because it will eliminate  the free chlorine and also protect your downstream membranes. This is normal practice with membranes  to reduce microbial biofouling.

2. Osama,

    

   To answer your question, the SMBS should be used prior to you carbon filter. The reason is to help and protect the carbon and get a longer use out of your filters.
   The carbon filter is a good fall back to the SMBS if you have any issues with it.

3. The oxidation/reduction chemistry of chlorine and SO2 or bisulfite is fast and complete. The only reason that bisulfite or sulfur dioxide would not be sufficient is that the treated solution  is not well mixed and/or you did not add enough to meet or slightly exceed the stoichiometry requirement. Forget the GAC.

4. probably you'll need it for RO and want to avoid the damage to membranes. I suggest you to use both, you can add SMBS first to remove the chlorine and use an activated carbon to be sure about it.

   1 Comment

   1. No. The bisulfite or sulfur dioxide will remove the chlorine. No need for activated carbon.But it would be better to add ammonia and produce chloramine at a ppm or less. It will reduce biofilm growth on the membrane.

5. Hi dear Osama

   If you insist on useing these methods, then you have to go for smbs first and then heading for activated carbon. But make sure that you are using a propper ORP meter in your system first. If you have huge flow of water then the carbon filter will be out of service soon. The carbon filter can help you with the Cl leftovers. It would be great if you can use an ORP meter in the outgoing water stream to make sure about complete Cl removal. Some ORP meters can inject proper amout of smbs acording to their system. But in case of decreasing the cost and the TDS  of outgoing water you can use ozonation process along with the ORP meter (actualy you only need one), especialy if it is a RO feed water. Instead of Cl you may also choose a propper UV system, then you dont have to use smbs, Cl and ORP meter.

   Stay safe.

    

6. We provide water quality test instruments like Residual chlorine electrode,COD reactor,rapid test strips.For any needs,plz contact me.Thx.

7. No need to use both.We just dose SBS three times the residual chlorine to fully get rid of.

8. If you are to totally remove all chlorine for purified water then you will need both.  In which case you will normally dose bisulphite first then use the carbon to mop up any residual chlorine.  There is a price for using carbon.  Firstly, it is a fixed bed and will need to be re-activated or replaced.  Secondly bacteria grow on the carbon and will release into the water.  If you are producing water for injections, this can cause pyrogenic reactions.  In which case it could be followed up by AFM (active filtration media) which will remove the residual bacteria, which have become released from the carbon.  If you use bisulphite and the water stands for a period of time, anaerobic sulphur bacteria will develop.

   1 Comment

   1. Not both. The reducing chemical will do very well.  As i commented earlier, converting the chlorine to chloramine is probably the best choice because it will help protect the RO membrane.

9. Not sure why you would have to use both.

10. why do you need both?  They both work well. I assume you are not treating drinking water and must have very high chlorine concentrations..  I would add the bisulfite, or even cheaper sulfur dioxide,  The GAC will eventually lose its reduction capacity, so use the chemical.

    1 Comment

    1. Hi, Joseph,
       The end user's consultant need to use both.
       Residual chlorine will be less than 0.5 ppm.
       will be used to feed an RO unit, drinking water application.
       Thanks

       1 Comment reply

       1. They should recheck their consultant. Who is it?  For 0.5 chlorine either would be fine. But actually the better choice might be to add ammonia and make chloramine which will help to control biofilms on the RO membrane.

11. Why are you removing the chlorine? That will have an impact on how to best stage the processes. What else is in the water besides the chlorine? What concentration of chlorine are you trying to remove?

    Carbon (at least some types) can act as a catalyst and convert chlorine to chloride without losing capacity. If the other compounds in the water will not impact the carbon, I would recommend the carbon first as it should provide the lowest operating cost and you will have to use less bisulfite.

    If your downstream use needs to have minimal residual bisulfite, I would recommend putting the bisulfite in first and under dosing and then using the carbon as a posher to provide the cleanest effluent.

    1 Comment

    1. Hi, Pat
       Residual chlorine will be less than 0.5 ppm.
       will be used to feed an RO unit, drinking water application.
       Coconut carbon will be used
       Thanks

       1 Comment reply

       1. Are you sure the consultants have specified the carbon for chlorine removal? Often an RO unit will have a carbon unit installed to remove organic matter in the feed to slow the fouling rate of the membranes. If the carbon is designed for organic removal, then any extra Cl- removal is just an extra. Normally you want to remove the Cl- as close to the RO membranes as possible to minimize the sections of piping that can show biological growth.

          If this was my project, I would probably do the carbon first and the bisulfite after, very close to the inlet of the HP pump and ensure the dosing pump is large enough to supply enough bisulfite to remove all of the Cl- and ignore any removal by the carbon.