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annracimo

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Is ammonia removal related to BOD reduction?
Feb 23^rd, 2012, 5:05am

Hi! I've been researching all day and I kept on finding myself stumped at that question.

I've been reading on leachate treatment and I'm just confused at the relation between the ammonia content and BOD content of the effluent. There are some companies that use good ammonia-removal as their selling point. But the purpose of my research is just concerned (mainly) with BOD effluent standards, in fact there are no specifications for the ammonia content.

I've read elsewhere that BOD measurements use ammonia inhibitors, so as I understand it, there isn't a relation between the BOD and ammonia concentration. However, there are still some who claim that removing the ammonia can significantly reduce the BOD content of the leachate.

am i overlooking something? Shocked

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jwcoke YaBB Newbies Offline I love Water and Wastewater.com Posts: 16 Pennsylvania Gender: Company or Organization: gregg township municipal autho	Re: Is ammonia removal related to BOD reduction? Reply #1 - Feb 23^rd, 2012, 7:45am BOD is a measurement used to calculate the stregth of a polutant including ammonia. It is not a direct measurement of ammonia. CBOD uses a nitrification inhibitor to prevent the conversion of ammonia to nitrate during nitrification.
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DS

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Re: Is ammonia removal related to BOD reduction?
Reply #2 - Feb 23^rd, 2012, 9:34am

Hi,

I thought it was recommended ( Huh

) to add a nitrification inhibitor in the BOD test (cfr. the standard methods of 1998). In the EU this is standard. anyway, it would be smart to do so in order to improve ( Lips Sealed

) the reliability, accuracy and relevance of the BOD test. BOD already is a problematic parameter, why increase the confusion even more?

If a wastewater contains a lot of biodfegradable COD, then bacteria also require N for protein synthesis. So there is some N-removal via normal bacterial growth. Not really relevant for most old leachates (unless for young dump sites) since these contain a lot of NH4-N and little biodegradable COD...

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grrun

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Re: Is ammonia removal related to BOD reduction?
Reply #3 - Feb 23^rd, 2012, 4:52pm

Measurement of BOD depends on DO depletion! Now NH₃-N can also be oxidized biologically. In my part of the country, the depletion of DO in the Illinois river was caused by wastewater discharge from Chicago (not from CBOD reaction, but from NH₃-N oxidation). Apparently, the flow from the Thames only took 5 days to reach the North Sea and I'm not sure that the oxidation of ammonia compounds was really recognized at the time the test was devised. It was just the Biological Oxygen Demand. Therefore, CBOD results may or may not be of significance in evaluating the performance of a WWTP. In the US, low limits on effluent nitrogen may account for the expanded use of CBOD.

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DS

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Re: Is ammonia removal related to BOD reduction?
Reply #4 - Feb 23^rd, 2012, 5:43pm

It is not about the Thames or what else possibly could cause DO depletion. It is about good and clear definitions of technical terms that are used in wastewater treatment technology and in its scientific approach (in which BOD (both cBOD and tBOD) is left aside more and more -luckily!). Including nitrification in the BOD value (and measurement) is not a very smart thing to do in terms of clarity and understanding of technical terms. Keeping the NH4-N value separate from the BOD (I mean cBOD, so ading a nitrification inhibitor in the test) gives more clarity, contrast, information.

In designing or operating plants, No one would lump together cBOD + NH4-N together into one "tBOD" value. Besides that, how would one discern that there might be an N-deficiency (industrial plants) if you only have a total BOD? Over here all BOD tests are done with a nitrification inhibitor, as also recommended in US- standard methods. shifting from tBOD to cBOD would be a good evolution, although cBOD remains a problematic meaurement and unit.

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Re: Is ammonia removal related to BOD reduction?
Reply #5 - Feb 23^rd, 2012, 7:49pm

I have to agree that the variability of BOD results have long been a problem for analysts; but regulators are generally attorneys who are only open to change when they lose a case. Since you have stated that cBOD "in order to improve ( ) the reliability, accuracy and relevance of the BOD test" results; do you know the +/-three sigma difference in the results between standards for BOD and cBOD? I have complained for years that BOD results are too variable; but I'm not sure that cBOD have improved the accuracy of the tests (only lowered the results).

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annracimo

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Re: Is ammonia removal related to BOD reduction?
Reply #6 - Feb 23^rd, 2012, 9:32pm

Thank you for your replies!

So, in my understanding, the companies offering 'ammonia-removal and significant BOD reduction' may mean that they included the oxygen needed to oxidize ammonia in the bod measurement?

the thing is, i've been looking at a uk-based company and an asia-based company. both offer leachate treatments but the emphasis of the uk-based company is on ammonia removal (then the bod reduction comes as corollary to it) with an mbbr while the asia-based company doesn't emphasize it (aerated lagoons with adsorptive media), though their plant still performs nitrification-denitrification as one of the treatments.

since we're only mainly concerned with the bod levels of the effluent (i really don't know why there are no standards for ammonia content of effluent here. Huh

), i was wondering if purchasing the uk-based company's plant wouldn't be necessary since ammonia content isn't our main concern.

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DS

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Re: Is ammonia removal related to BOD reduction?
Reply #7 - Feb 24^th, 2012, 5:08am

Grrun,

I think we agree.
the cBOD already bears a lot of errors, inherent to 1) the wastewater to be tested, 2) the methodology itself and 3) the inoculum. I do not have figures but I apply the range of +/-20 % error on BOD data, and they tend to become much bigger at low values (cfr discharge)
Not inhibiting nitrification will be even much worse since a big factor of variability (viz. nitrification itself) is introduced; variability may come from N-compounds (and the completeness and rate (5 d?) of protein breakdown releasing N that must be nitrified), from the activity of nitrifiers themselves, nitrification rate, nitrification completeness (till NO3?), nitrification inhibitors (complete or partial inhibition, increasing a lag, etc?), salt concentrations, pH effects, etc etc.
My point is that all BOD should be cBOD so that adding a nitrification inhibitor should become the standard method, and I think (again, I have no figures, because BOD is out of my interest, I do not use it and it has been ages I have had it analysed) that both accuracy and precision will be better in cBOD then in tBOD for reasons I meantioned above. Besides the reasons of accuracy and precision, I think that lumping together NH4+ oxidation and bCOD-oxidation is not a smart thing to do.

AnnaRacimo,

a few thoughts:

1) find out what both suppliers exactly mean: your goal is not to provide enough oxygen (although you will have to), but your goal is to lower the concentration of pollutant(s) below the discharge level. What exactly is the promise of the supplier?

2) In most leachates, the BOD is low to very low, whereas the NH4-N often is high to very high. sometimes there are also problmems with salt and heavy metals and some special pollutants (if also industrial waste was dumped in significant (?) amounts). So, mostly the problem to deal with is the NH4-N. So I am surprised that you only have a norm on BOD and not on NH4 or Ntot. Since the strong eutrofication potential of such water, I think it is quite well possible that the norms will be changed. Maybe you should keep this in mind

3) If you are clear and sure about your short and long term objectives and if you stick to only BOD removal, I think a very small and simple WWT will be sufficient. BOD removal is one of the simplest things to achieve, though the matrix (salt, pH, ..) may be a bit difficult. Ammonia removal is much more difficult to achieve and if you finally have reached that, BOD will be removed as well. "You do not go to Moscow to buy some eggs, do you?"

If I were you, I bought the outcome (= the result) you need (and they have to guarantee that with a bond), rather then buying some equipment (which they will supply). do not forget to include the system and process requirements which need to be guaranteed (+ bond) by the solution provider as well.

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Re: Is ammonia removal related to BOD reduction?
Reply #8 - Feb 24^th, 2012, 10:27am

I agree with DS generally. However, is this a real world problem or just an exercise? Frankly, many other factors need to be considered for real world problems because the choices you've considered are not equal in many ways, but are somewhat extreme. In the real world, performance in terms of effluent quality are certainly primary, but economics (both capital and operating costs) are the second most important considerations. I'm not sure how these other factors should be quantified and DS is better qualified to estimate these factors than I am.

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DS God Member Offline sapere aude Posts: 1583 Company or Organization: Indept. Freelance Consultant	Re: Is ammonia removal related to BOD reduction? Reply #9 - Feb 24^th, 2012, 12:18pm I think that good understanding of basic concepts is important, especially on a help forum.
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