I am operating a small sbr plant, (.5 mgd), I am having problems with one of my basins being sky high in ammonia. Will raising my react time lower my ammonia? Need help quickly, EPA is looking over our shoulder. What would be the fastest way to get the ammonia lowered? I hope someone has a suggestive, I'm desperate!!!

Thanks,

Laurie

Laurie

You should check your DO levels in that basin. Increasing your react time may help providing you are putting in more air and not just spreading the same air volume over longer.

I would be checking the following.

That your loading is fairly evenly spread between basins.:Compare top water levels cycle by cycle , inlet valve opening times , decant times etc

DO levels: Don't just trust your online systems use a calibrated portable. Check several times during the react period. You are probably going to need DOs around 2mg/l but it you may need more or less depending upon a lot of factors.

Do you have a way of measuring air volumes in each basin?

As previously suggestted check the pH levels during the react period. If they are dropping below 6.8 you may be having trouble.

Without knowing your plant configuration short circuiting can also be a problem particularly if you have flow coming in during settle or decant. If you don't think you have this problem or you don't know it would be worth checking that your inlet valve is actually shut and no flow getting through. If your SBR is rectangular with the length twice the width or more it will probably not be an issue but in a circular or square basin this can be an issue.

Make sure the SRT in both basins is adequate or similar . Are the MLSS close to the same in both basins. If not this could indicate that SRT is different or the loading is substantially different.

Regards

TerryF

Thanks for all the helpful info and suggestions. I sit down this morning and compared data over the last 24hrs. It does seem that my #1 basin (the one that has apprx. 1mg/l of ammonia) is more consistent with its cycle times, and my #2 basin(the one that has apprx. 20.0mg/l ammonia) is not very consistent. I only have 2 basins. #1 is averaging 90min anoicic fill, 90min aerated fill, and 50min react time. #2 has anoxic fill from 30 to 85min, aerated fill from 90 to 140min, and react from 8 to 50min.  They are circular basins. For whatever reason, #1 maintains 2100 - 2700 mlss, it can also go as low as 1800mlss and as high as 4000mlss without it making much difference in the ammonia levels. On the other hand, #2 is very picky, it doesnt seem to matter if I run high or low on mlss, I cant seem to get the ammonia levels down. I have noticed that if I try to run #2 at 2100-2700mlss, it seems to decrease drammatically in bugs. Very few f/s and stalks at this level, and I fear that I will waste out if I try to keep the mlss the same in both basins. 90% of the time, #1 is my peak basin, and it doesnt seem to matter a whole lot if I make changes to it, it seems to adapt, but #2 is definately my problem child. I dont have automatic D.O. meters in the basins, I just read them in the lab(which is only 60ft. from the basins. But I do have a portable D.O. meter, and I will check the basins during react as per your suggestion. If you have any other suggestions, I sure would appreciate them.

Thanks, Laurie

As a general rule of thumb, ammonia will be converted to nitrate better with:

higher MLSS

longer react time

more air

sufficient alkalinity

David

I've read that it takes 7.1mg/l of alkalinity to lower ammonia 1.0mg/l, is that true? And if it is, how do I raise my alkalinity in the system to accomplish that?

Thanks, Laurie

Laurie

You will also need about 4.5 parts of oxygen. But alkalinity is usually 150 - 250 mg/l in domestic wastewater. Good luck !

Bob Whitworth