Hydrogen Peroxide Increasing BOD

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Hydrogen peroxide is effecting the biochemical oxygen demand (BOD) in our activated sludge plant. 

The local jail is using hydrogen peroxide for the laundry service they provide for inmates' clothing.

I need help with resolving the issues with high BOD. How can I reduce it? How can I mitigate the effects of hydrogen peroxide? 

The treatment plant is an activated sludge plant with selector cells for nutrient removal. The final effluent is filtered through MBR's and the water is either reused or injected back into aquifer. The plant is considered a Class A reclaimed water facility.

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17 Answers

  1. Sorry about the confusion but it's actually raising the COD and lowering the BOD and this is on influent only. They still have great effluent but the concern is the test results are skewed. BOD average was 300 mg/l and now averaging 80 mg/l. It was bad information that it was coming from the jail. The H2O2 is coming from a laundry mat that did a large expansion. Flows haven't changed. Any thoughts and let us know if additional information would assist. 

  2. Sorry about the confusion but it's actually raising the COD and lowering the BOD and this is on influent only. They still have great effluent but the concern is the test results are skewed. BOD average was 300 mg/l and now averaging 80 mg/l. It was bad information that it was coming from the jail. The H2O2 is coming from a laundry mat that did a large expansion. Flows haven't changed. Any thoughts and let us know if additional information would assist. 

  3. Hi Chad,

    Are you saying that a high amount of Hydrogen Peroxide in your wastewater stream is killing the biology in your biological system?

    Thank you,
    Ray.

  4. Regarding the measurement of COD, we have confirmed through an on-going COD reduction project in Finland that H2O2 is a positive interference for the dichromate COD test (CODCr), increasing the results.  To compensate for this a separate titration for H2O2 was completed by one research partner and then subtracted from the CODCr results.  The other partners are using the photoelectrochemical (peCOD) method.  A green chemistry method with results in 15min.  The peCOD does not suffer from the H2O2 interference and measures the correct COD value in one step.

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  5. It should be possible to neutralise the effect of variable dose of H2O2 by enabling the waste water flows from jail on CaCO3 stone bed. Alternatively, just before the start of final treatment process, neutralising Agents should be introduced to remove the ill effects of H2O2..the residual Oxygen atoms...Reading of BOD levels of the waste should be adjusted after neutralising H2 O2 in the sample... 

  6. Dear Chad,
    As per my knowledge, unreacted or residual Hydrogen Peroxide in a sample is responsible for " False low BOD values ". This is because residual Hydrogen Peroxide liberates oxygen over the test period. 1 mg/L of H2O2 liberate nearly 0.5 mg/L of DO, thus giving false low BOD results. So i think its incorrect to say BOD values are increasing due to Hydrogen Peroxide. However the fact can not be denied that COD increases due to residual H2O2 because it consumes the oxidizing agent Potassium Dichromate giving false high COD values.

  7. Dear Chad,

    The question seems not complete.

    If you could share what was the Pollution Load (BOD, COD, pH) earlier and now after using H2O2 what changes (increase) has been noticed in (BOD, COD, pH). 

    Main question which is not present here, were they using H2O2 while the Treatment plant designed or it is a new process change in Laundry?

    Does your wastewater increased as well. 

    Please check any other stream in not introduced from any other source.

    Having an Activated Sludge Treatment on the Basis of MBR (Membrane Bio Reactor) gives quite good discharge and meets the Discharge Standards up to level of BOD

  8. It is best to use COD, rather than BOD, as the primary metric for the plant load. COD is a conserved parameter (i.e. you can do a mass balance on COD through the plant) whereas BOD is just a measure of what is oxidised by the inoculum in 5 days. Nearly all of the COD will be removed in your treatment plant, either by oxidation or assimilation, so the COD will give a better estimate of the oxygen demand. 

    As has been said by others, peroxide might increase the BOD by converting slowly-degradable organics into measurable BOD, whereas peroxide will cause a reduction in COD.

    You haven't specified what problem you're having with a high BOD. Is it just that you are having problems measuring BOD accurately or is your plant overloaded (high COD load)?

  9. Using peroxide can increase the amount of BOD5 by making what were insoluble organics available for degradation in a 5 day test. You can check for this by comparing BOD5 with COD BOD20 numbers.

  10. I  agree that  something  does  not  add up here.  I have  worked  with  a  large  industrial laundry in  a  small town and switching  to peroxide( from chlorine)  only had a positive effect. No  problems (including change in  BOD) were  noted.  I suggest investigating to see what real problem is…. until then I suggest having prison equalize their flow to plant, if this is not already practiced.

  11. Hi Chad,

    If you are seeking something to reduce the BOD, we have a pure mechanical process developed togehter with TU Vienna. Pure spring water has a natural content of approx. 4 mg Oxygen/ltr. With our methode we are able to increase the oxygen content up to 20 mg/ltr in open or closed (circulation) systems. A combination with ozon is possible, We use ozon only for cooling tower disinfections, as the ozon radicals have a much bigger impact on the removal time of all biofilm(slime) material.  We use this technology to purify water and or disinfect water.  100 % chemical free and certified by TUEV Vienna. Happy to assist further, kind regards, Gerhard.

     

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  13. We have similar effects with samples of ozone treated waste waters. I strongly support Geralds explanation.

  14. Yes Oxidant can lead to an increase in BOD by breaking down some more recalcitrant COD "hard COD" rendering the effluent more biological active.

    Why is this a problem? are you sure that the BOD load of the effluent hasn't changed?

  17. Hi Chad, the direct impact of hydrogen peroxide causing an increase in BOD from a pure chemistry stand point is illogical. What assumptions or data have led you to this conclusion? From my experience I would suggest that the detergent perhaps aided by hydrogen peroxide (or high flow rates) maybe scouring sewage pipework and the inevitable accumulated bioslime which I would assume is the direct cause of the increased BOD. Happy to assist if you can provide more information/data/evidence to support your claim. Kind regards, Ray