Water and Wastewater.com Help Forums

A Beak Junior Member Offline I love Water and Wastewater.com Posts: 80 Company or Organization: City of Biddeford WWTP	Soluablility of NO2 Apr 18^th, 2012, 10:46am Hello. If you were to test for nitrites on mixed liquour supernatant and then filter the same supernatant and test it again, do you think there would be a signifigant drop? Thanks.
Back to top	IP Logged

The sludge judge God Member Offline Posts: 649 Wisconsin Gender: Company or Organization: private	Re: Soluablility of NO2 Reply #1 - Apr 18^th, 2012, 11:43am nitrates are soluble- it probably depends on how clear your supernatant is. Sometimes for "quick and dirty" I'll just use a peice of paper towel to filter it first. (for inhouse data only of course). If it's reportable then standard methods must be practiced. best regards, Ryan
Back to top	IP Logged

David S.

Senior Member

Offline

I have nothing
clever to say here.

Posts: 373

Gender: male

Company or Organization: Environmental Express

Re: Soluablility of NO2
Reply #2 - Apr 18^th, 2012, 12:08pm

I think it would depend on the test method and how well you were able to remove the liquid portion to do the secondary testing. Nitrite compounds are all very soluble in water except for silver nitrite. If you were to measure by colorimetry or ion chromatography you will probably get similar numbers due to the fact that the sample will need to be filtered prior to performing these tests. If you use an ion selective electrode you will probably get a smaller number after filtering because of the inefficiency inherent in the filtering process.

Back to top

Working hard to bring reason to the field of regulation.

IP Logged

The sludge judge God Member Offline Posts: 649 Wisconsin Gender: Company or Organization: private	Re: Soluablility of NO2 Reply #3 - Apr 18^th, 2012, 12:14pm agree, I accidently said nitrates instead of nitrite.
Back to top	IP Logged

DS God Member Offline sapere aude Posts: 1583 Company or Organization: Indept. Freelance Consultant	Re: Soluablility of NO2 Reply #4 - Apr 18^th, 2012, 12:28pm I agree with the others. differences between the samples may occur due to denitrification by bacteria present in that sample, unless the DO remains high enough to prevent denitrification.
Back to top	www.AquaICS.be IP Logged

A Beak

Junior Member

Offline

I love Water and
Wastewater.com

Posts: 80

Company or Organization: City of Biddeford WWTP

Re: Soluablility of NO2
Reply #5 - Apr 18^th, 2012, 2:00pm

Thanks! Maybe you guys can help me with somthing else that I am confussed by. The reason I am testing for nitrites is that i was on vacation the last week and a half and when i got back the pH in the AB's had dropped to less than 6.0 and the demand for chlorine had skyrocketed. We typically fully nitrify. So i took a few samples to check for nitrite acumulation. (we have run into this problem before) What i found is that the AB's seem to be nitrifying just fine. (high NH3 coming in, high NO3 with <.01 mg/L NO2 and <1 mg/L NH3) But then coming out of the clarifiers the effluent NO2 jumps up to >5 yesterday and 1.2 mg/L today. Can somone explain what is happening? I checked the DO in the clarifier today and it was 0.4. Thanks!

Back to top

IP Logged

DS God Member Offline sapere aude Posts: 1583 Company or Organization: Indept. Freelance Consultant	Re: Soluablility of NO2 Reply #6 - Apr 18^th, 2012, 2:10pm A beak, probably you are observing partial denitrification; settlers are "not the most optimal places to perform fast and deep denitrification", so the whole denitrification reaction maybe rate limited, due to too little rbCOD present. Don't you have predenitrification in which nitrate can be removed faster/better?
Back to top	www.AquaICS.be IP Logged

A Beak Junior Member Offline I love Water and Wastewater.com Posts: 80 Company or Organization: City of Biddeford WWTP	Re: Soluablility of NO2 Reply #7 - Apr 19^th, 2012, 7:09am Thanks DS. Unfortunately, we do not have a place for denitrification so we normaly do not denitrify. Could you elaborate more on partial de-nitrification? I am not formiliar. Thanks again! AB
Back to top	IP Logged

A Beak Junior Member Offline I love Water and Wastewater.com Posts: 80 Company or Organization: City of Biddeford WWTP	Re: Soluablility of NO2 Reply #8 - Apr 19^th, 2012, 7:10am Also, What is rbCOD?
Back to top	IP Logged

DS

God Member

Offline

sapere aude

Posts: 1583

Company or Organization: Indept. Freelance Consultant

Re: Soluablility of NO2
Reply #9 - Apr 19^th, 2012, 7:22am

A Beak,

Partial denitrification or incomplete denitrification; the reaction goes slow or stops, yielding denitrification intermediates (denitrification is a series of reactions) like Nitrite and/or the like (cfr NO, N2O etc). some of these are also detected as Nitrite.

rbCOD = readily biodegradable COD (e.g. VFA); denitrification with this fraction of the COD is much quicker then with slowly biodegradable COD.

Maybe there are parts of your aeration tank that can be made anoxic (unaerated)? add nitrate recycle, RAS and influent, and you have ingredients to be able to do it. This needs to be further worked out in detail, but it sets the idea.

Back to top

www.AquaICS.be

IP Logged