Color Removal from Pulp & Paper Industry Effluents.

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I am trying to remove the color of the pulp and paper industry effluent. 

Our WWTP consists of the primary and secondary treatment (activated sludge) systems. 

We introduced a new washing system for the bleaching stage (acid effluent). Since then the final effluent color has significantly turned darker (around 1000 mg Pt/L). Additionally, the final effluent chemical oxygen demand - COD has also increased. 

What is the explanation for this significant color and COD increase? How can I remove the color of the effluent? 

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29 Answers

  2. Please use Ferric Chloride to remove colour, before you dose you must consider a Jar Test to determine the dosing rate versus flow rate.

  3. Please use Ferric Chloride to remove colour, before you dose you must consider a Jar Test to determine the dosing rate versus flow rate.

  4. Please use Ferric Chloride to remove colour, before you dose you must consider a Jar Test to determine the dosing rate versus flow rate.

  5. Dear Carlos,

    If you are using a bleaching agent, it may contain certain amount of chlorine in it as well. Probably due to this the sludge mass has mostly reverted back to anaerobic phase or is dead. Only due to this, the problem of darkening of colour is present. if you can segregate the water stream, and connect it post aeration and pre-filtration, your colour may improve. Only after this step, you may need to check whether the carbon that you have used has a good iodine value. If not, my advice will be to replace it.

     

    Regards,

    Sagar Apte

  6. The bleach liquore shall be segregated from the main effluent and it should be treated with micro enzymes available in market or else even after bringing the colour down it reappears since this waste contains lignins

  7. The bleach liquore shall be segregated from the main effluent and it should be treated with micro enzymes available in market or else even after bringing the colour down it reappears since this waste contains lignins

  8. Don't know if this is possible (depending on the rate/volume of effluent flow), but could you "polish" the effluent with a carbon (granular activated carbon, GAC- F600) flow through tank?

  9. I have limited knowledge and experience in the area yet felt can help so venturing in with a suggestion.

    As far as I understand the colour is because you are using wood, essentially Lignin so why not digest lignin first using an appropriate enzyme.Can suggest and demonstrate a natural source as well. The other problem is the issue of heavy metals in the effluent so even for that can suggest Bioremediation.

  10. I have limited knowledge and experience in the area yet felt can help so venturing in with a suggestion.

    As far as I understand the colour is because you are using wood, essetially Lignin o why not digest lignin first using an appropriate enzyme.can suggest and demonstrate a natural source as well. The other problem is the issue of hevy metals in the effluent so even for that can suggest Bioremediation.

  11. Dear Carlos,

    The increase of both COD and color after biological treatment is explained by the higher fraction of recalcitrant organics including lignin compounds (brownish color) after changing the washing in the bleaching stage.

    Because traditional activated sludge systems including MBR, remove mainly readily biodegradable soluble organics (“fast” food), we upgrade this to capture and biodegrade the “slow” food  and recalcitrant organics including color as well without using any chemicals. In 2009 we applied this in a large pulp & paper wastewater treatment resulting in very low COD and color (80% - 90% removal).

    If interested, I would be happy to send you more information via email.

    Regards, Bruno.

    1 Comment

    1. Dear Bruno,

      I would appreciate if you send me more info on this to schmidt.quadros@gmail.com.

       

      Regards,

      Carlos

  12. @ Carlos,

    The solution can be designed with simple setup.

    Anaerobic digestion in first stage if systems suits your country's climate.

    Followed by Electro-Cogualation --> filtration with mechanical press filters --> Ozone diffussion to settle balance COD / BOD and need be little chlorine (only if required) periodically.

    In case anareobic digestion is not working for all seasons  then Primary Filtration with 3 Micron press filter followed by Electro-Coagulation followed by Press Filter again and then Electro-Oxidation

    Solutions to all complex problems need not be Complex always!

  13. Dear Carlos,

    Physicochemical methods  

    Physicochemical methods   like coagulation with lime or iron salts, ultrafiltration etc. have not been very effective for color removal of pulp & paper mills effluents. Adsorption of activated carbon is a common method for color removal of industrial effluent but the high cost is a limitation for its use for pulp & paper mills. Therefore attempt has been to find out low-cost adsorbent material for removing color of effluents of the industries. Coal fly ash of power plants has been used as an adsorbent for removing metals like Hg,Pb,Cd, Zn and Fe from water (De, 2005; De & Lal, 1990).But use of coal fly ash for color removal of Pulp and paper effluents has not been reported. In the present investigation , coal fly ash has been  used for the color removal of pulp and paper mill effluents. Coal fly ash is an efficient adsorbent in removing color of pulp and paper mill effluents.100% color removal was achieved at pH 6.8 and above.

    Effect of pH

    Effect of pH Effect. of pH on  color removal of the paper mill effluent was studied using 0.5 M NaOH or 0.5 M HCl (Fig. 2). 100% color removal took place at pH 6.8 and above. This result is significant as normal pH of paper mill effluents are above 8.0,  the method may be used  for color removal of pulp and paper mill effluents without any pH adjustment.

    Colour removal by active and gamma sterilized compost

    Color removal experiments using active and gamma sterilized compost showed that the color removal capacity for both wastewaters was nine times higher when using active compost than for those reactors using gamma sterilized compost. Final decolorization for pulp mill upset tank and E stage filtrate was 91 and 83%, respectively, while only 33% decolorization was achieved with gamma sterilized compost. Kinetic tests also showed higher color degradation rates when using active compost compared to sterilized compost. Additional experiments demonstrated that biological color removal appears to be robust with respect to pH and is largely unaffected by pH over a range from pH 5 to 10, typical values for the effluents in paper mills. The effect of aging in sorption were tested and results showed that virgin compost could establish a microbial population in less than 50 days which resulted in a compost with sorption capacity similar to the aged compost.

    Colour removal by Membrane

    Membrane technology has become widely accepted in many seawater and brackish water  treatment applications and these days it is more often used also in variety of waste water treatment processes as the final treatment step of water re-use process. In addition to traditional use of membranes for desalination, new requirements have been challenging membrane manufacturers to develop special products for selective removal of hardness, natural organic matter, color, fats, proteins and other macromolecular species. Nanofiltration (NF) membranes are usually used for selective removal of certain species in applications when TDS reduction is not a priority.

    Colour removal Coagulation Process

    The pulp and paper mill effluent is one of the high polluting effluents amongst the effluents obtained from polluting industries. All the available methods for treatment of pulp and paper

  15. Dear Carlos,

    As you know, in any wastewater treatment application the bulk of the work has to be done by bio filtration.

    If you have considerable colour problem, you should probably see if you could optimize or improve your bio filtration system.

    If you like I will gladly give you some good ideas how to improve efficiency of your bio filtration and aeration.

    The better and the more effective is your bio filtration the less expensive will be the polishing and colour removal system, using oxidizers as ozone and the whole project will be more economical.

    Mechanical micro filtration is typically way too expensive as far as energy consumption is concern to be used in wastewater treatments.

    1 Comment

    1. Dear Misha.

      Sorry for the late reply. First of all, thanks for your comments on this subject. As you propose, I woul be interested in hearing your ideas on how ​to improve ​efficiency of ​your bio ​filtration and ​aeration.

      Regards,

      Carlos

  16. Dear Tim, 

    Ozone generators which are typically used in pulp and paper industry are producing ozone in kilograms and even tons per hour, using ozone generators similar in size to an elephant. They typically are treating millions of litters of water. Do you produce such equipment or are you familiar with this size of ozone applications?

  17. Dear Mickey,

    I am afraid that your opinion is based on incorrect ozone implementation and most likely poor quality and technologically inferior equipment. Unfortunately over 95% of ozone applications are done by people ignorant of ozone technology and that make results of the implementation ineffective, inefficient and expensive giving ozone stigma and bad name.

    My opinion is based on thousands of ozone system installations done all over the world and calculations.

    When I have done comparative calculations in the past with many oxidizing technologies vs ozone and they we considerably more expensive. If you are interested please bring forward an example of a technology that you consider comparable in price and we will see which one is more economical right here in the descussion.

  19. Hi Carlos, I am a supplier of aqueous ozone from clean core technology, 3gpm or more if needed. On demand when all that is needed is cold water electrical outlet, our unit only uses 2.5 cents per hour of electricity, If ozone is what you want contact me. 

  20. My experiences to treat black licquor with Up flow Anaerobic Sludge Hankering continued with Up flow Anaerobic Fixed Mediia. Control pH 5.5-6.5 in range to produce Methane gas. The efluent from this system will remove 95-98% of COD. So the affluent will about in 950-1500 ppm in easy for aerobic activated sludge in the next processing.

  21. I have a feeling that you should try Ultra Filtration (UF) on the worst colored effluent streams. I have not tried it for textile effluent, but I think it should work as these coloring molecules are high molecular weight compounds.

  22. Good evening!
    Wedeveloped the technologyand equipmentforthe processingwhichcanpurifyany types ofwastewater, includingcolorremovewaterand suspendedorganicsmechanicalimpurities.
    Sendyour e-mailaddress andI will send youa presentationof our technology.
      I bet-after ourcleanwater isclear.
      We cancomewith their own equipmentanddoa testcleaning.

    1 Comment

  23. Good evening!
    Wedeveloped the technologyand equipmentforthe processingwhichcanpurifyany types ofwastewater, includingcolorremovewaterand suspendedorganicsmechanicalimpurities.
    Sendyour e-mailaddress andI will send youa presentationof our technology.
      I bet-after ourcleanwater isclear.
      We cancomewith their own equipmentanddoa testcleaning.

  24. Carlos,

    There is an effective process to remove the recalcitrant color from black liquor and bleach effluent. The process cleaves the chromophores from the polyphenol molecule. The color does not return. COD/BOD values are also substantially reduced in the process.

    Biological oxidation system often increases true and apparent color content as the waste is process. Biological systems reduce the molecular weight of the molecule often making the resulting polyphenol sister molecule more recalcitrant in the effluent and in the environment. Sample testing for color indicates substantial increases as the effluent pass through a biological process such as an aeration stabilization basin.

    Ozone technologies works however the systems exhibit high Capex and Opex costs due to the high biological concentrations and high mass volumes in the discharge.

    Cheers,

    Philip Kemp

    Mason Kemp Associates – On LinkedIn

  25. Dear Carlos:  The removal of color and correction of the COD levels in the effluent is well documented using ozone.  I suggest that you follow the suggestions posed by Misha  and set up the pilot plant for a demo of the effectiveness of the proposed system.  

  26. Dear Carlos, you may be interested to learn about the Eureka ACQUEAU labeled project for Pulp and Paper Mills:  http://www.acqueau.eu/projects/2016/2/1/corecod-1  It includes an advanced oxidation based COD analyzer providing results in 10min, online and it measures recalcitrant COD.  See more here:  http://www.mantech-inc.com/pecod/  We have data from FPInnovations (Canada's Pulp and paper Research Inst.) that I can send to you if you like.  Best Regards, Robert  rmenegotto@mantech-inc.com 

    1 Comment

    1. Thanks Robert.

       

      Will check it.

       

      Regards,

      Carlos

  27. Dear Carlos, 

    Ozone, if implemented correctly after a bio reactor is very effective and economical in colour removal in textile and pulp and paper industries. The systems is very simple and easy to implement and on the long run will cost less than any alternatives that I have seen, due to low power consumption and raw product for ozone production being air. Unlike any chemicals that you need to buy, air is free...

    If you are interested I could assist you in putting together a small and inexpensive pilot system that will not only illustrate how effective the ozone is in colour removal applications but will allow you to establish the size, price and operating cost of full scale industrial ozone system, that will solve your problem.

    The same pilot system with some modifications will allow you to test most of the alternative technologies suggested here and to compare effectiveness and feasibility.

    Small investment to construct a small pilot test system will qualify for any R&D tax credit (which will make it revenue neutral), will completely remove any risk (colossal waste of money on ineffective system) and guess work from your project.

    Best Regards,

    Misha@AbsoluteOzone.com

  28. Dear Carlos,

    The increase in COD and color after biological treatment is explained by the increase of recalcitrant (hard to biodegrade) organics including lignins (brownish color) resulting from the process changes (acid effluent from bleaching). Depending on the operating conditions in the activated sludge stage, the color may even increase due to intermediates.

    That's why we upgrade the activated sludge process as to capture this fraction into regenerated biosludge for subsequent biodegradation by microbial enzymes within the biosludge. In this way we achieved over 80% color removal at 50% to 70% lower COD in a large pulp and paper mill back in 2010.

    If interested, I would be happy to send you more information by email.

    Regards, Bruno

    1 Comment

    1. Dear Bruno,

       

      Sorry for the late reply. Yes, I would be very much interested in getting more info on that.

       

      Best Regards,

      Carlos

  29. Dear Carlos,

    Hope u r doing well

    for colour removal from paper industry effluent; ceramic membrane technology is the best solution.

    You can send me the parameter of your effluent so i can suggest u the best ceramic membrane on basis of effluent quality.

    Plz write me on umeshagola@gmail.com 

    Umesh Patel

    +91 8980090345