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?
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.
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.
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.
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.
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.
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.
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
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.
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.