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RE: How to lower ammonia level in an sbr plant

D Shulmister — Mon, 22 Oct 2007 13:13:10 GMT

Bob is correct -- the alkalinity numbers sound way off. My plant influents usually run around 100 to 140 mg/L alkalinity. You won't get conversion of ammonia if there is not enough alkalinity.

RE: How to lower ammonia level in an sbr plant

bugwisperer — Sun, 21 Oct 2007 15:11:57 GMT

TerryF (10/21/2007)

I must have been away the day we were taught the relationship between floc size and MLSS , but maybe things work differently at higher elevations.

Here in the deep south this is how things work. For a given plant and a given load if i increase my MLSS theoretically i can get by nitrification wise with a lower DO. The total air required may go up a little because of greater endogenous respiration but the plant will work with a lower DO. The relationship is not linear but is proportional to some extent. Suprisingly enough the design equations for nitrification also support this relationship.

Last time i looked this was one of the principles behind oxidation ditches: Big tanks , lots of biomass (low F:M) but generally lower DOs which produces stable nitrogen removal performance.

Now with my given plant and my given biomass if i suddenly have a big hit of ammonia i require more air to increase the oxidisation of the ammonia and as the nitrifiers have to work harder i may have to raise the set point to achieve adequate oxygen transfer. (See comments in one of my previous posts about an overloaded plant requireing 4mg/l).

Many plants that are under aerated for whatever reason may show some improvement in nitrification capacity if the MLSS is reduced because the endogenous demand is reduced enough to increase the DO in the MLSS enough to get some oxygen transfer happening. Alternatively the aeration rate could be increased which would achieve the same thing.

At least i think thats how it works!!!

TerryF

Well, I believe the F:M and mixing energy provided will in fact impact the size of the floc particle. You know - quantity and characteristic of EPS bug glue on cell exteriors? Case in point - everyone "knows CBOD reduction has to be down in the range of 20-30 ppm before nitrfication really kicks in"... right? whys that? why doesnt separate stage nitrfication work real well and why do the nitrifiers have a tendency to wash out in such process configurations? It is because nitrifiers are really heterotrophic wannabees and live to incorporate themselves into the heterotrophic floc particle or onto the fixed film depending on the process? Ok, so we know where the nitrfiers like to hang out. How come nitrfication doesnt kick in (full steam) the first minute when the first drop of wastewater enters the aeration basin? Could it be that the bulk fluid DO is scavenged by the heterotrophs occupying the surface of the floc particle such that the DO on the interior of the floc structure is so low that only a minute fraction of the autotrophic organisms have adequate DO for nitrification? This is exactly what happens. Until the oxygen demand is reduced to close to the endogenous (carbon largely gone) demand the autotrophs are not hitting on all 8 cylinders - ok, 6 cylinders with a turbocharger. In cases where we have a very heavy mixed liquor and need to achieve the maximum nitrfication rate because the engineer didnt get the client to pay for a treatment tank way bigger than it really needs to be, then we are going to need to run a DO over 4 ppm to achieve this maximum rate,ie, using all the autotrophic organisms in the process as efficiently as God allows them to be. Again, mixing plays into this too from the perspective of insuring even distribution of DO and nutrient throughout the bulk fluid. Think of it this way - you have a crowd of a million people standing shoulder to shoulder versus a million people standing at arms length to each other. If you had to walk thru the crowd which would be easier? (possible?). I have a hard time diffusing oxygen into the tight crowd - cant get it in all those nooks and cranies unless I create greater force in a higher DO to drive it in there - chem E stuff you know - higher temp to lower temp - higher concentration to lower concentration drives the rate of the reaction so to speak. To get thru the tightly packed crowd you would have to have one heck of a big guy (high DO) behind you pushing. And, I maintain, the same applies to DO, MLSS and the floc particle itself - the high DO pushes through the crowd of organisms in the bulk fluid and floc particle so when it finally reaches, Fred and Mary, nitrifiers of good repute, they have enough DO remaining such that they can do their thing at an optimal rate. Certain things in wastewater just arent taught in school - I believe I have a paper in work from some PHd type who somehow actually measured DO on the floc scale basis although that happened to be in very recent times. In an SBR one doesnt have a lot of time to mess around - dilute your influent ammonia by 1/3 (say the batch volume) to say what - 18-22 ppm?? so we have to spend a half hour doing our CBOD reduction from say 80 to 10 in consideration of mix and then have the rest of the time allocated to nitrfication. We should get a pretty good specific rate and have this done in what - 4 -5 hrs maybe.

There is no question nitrfication occurs at low DO; we run a small plant , domestic wastewater local to our office at about 0.45 ppm at MLSS = 3000. We completely nitrify and typically have a total N going out of less than 2 ppm; permit is 10ppm as it goes to the ground. Its an MLE plant, ie, no second anoxic. Did I mention there is about 2 days HRT? ie, nitrfication rate and denitrification rate are not optimal but there is boocoos of time in the process so no biggie - we get by with the slower rate and as a side bonus achieve a lower TN than we otherwise could with an MLE process. Same approach as the symbio gizmo sans the messing around, and oh, pay no attention to that capacity issue. Play games with DO and nitrify and denitrify simultaneously but for a given MLSS concentration the sweet spot DO (DO at which we are nitrifying and denitrifying at a rate high enough to achieve our permit goal within the time in the process) will be higher the higher the MLSS.

As we are aware, extended aeration and oxidation ditch (ie, extended air plants with a psuedo 200Q internal recycle pump) processes are as big as they are and were developed not because the treatment time is actually needed to achieve permit if the reaction rates are not purposely (or by accident) limited ; they are as big as they are: 1. to minimize sludge production, 2. civil engineers (and I is one) are going to have a harder time screwing things up and not achieving permit if they design this process. 3. You know- 1-800-Vendor. One can run ammonia on a normal domestic waste extended air plant about half way thru the process on supernatant from the 30 min settle test and read 0.1 ppm year round assuming DO and alkalinity are not limiting. Nitrification rate is nitrfication rate, ie, zero order, over the two-Ks value for ammonia, ie, run the ammonia up above 1 ppm, as high as you want - nitrification rate aint going any faster. Its first order relative to bugs, ie, the more you have, the faster you go at a given temp to the extent you have ammonia available in the process for them. You can raise the SRT as high as you want but it doesnt mean you are going to have more and more nitrfiers - that will be limited by the raw wastewater N and the contribution from heterotrophic decay. If a system is overloaded with regard to ammonia such as one that might have a contributory school (because the engineer didnt know the "ammonia" was not 45 ppm and TKN was really 130 ppm ish) then running a 4000 MLSS with a lower D.O. isnt going to cut the mustard. Its not because the ammonia concentration is higher, its because we arent effectively using all the nitrifying organisms we have in the process to nitrify at the maximum rate they are able to if they have an unimpeded source of DO. We had terrible trouble at a plant in FL which we ran MLSS at 5000 to 5500 in the high season when all the snowbirds came down for the winter. The problem was we did not have isolated blower piping so we had to try to balance the air with butterfly valves - by the click you know. Inevitably backing off one basin one click and opening another basin one click wouldnt take the DO from 5.8 ppm (excellent nitrficiation) to 5.0 ppm in one basin and from 3.8 ppm (poor to little nitrfication) to 4.8 in the other basin - it would be like 5.8 to 3.5 and 3.8 to 5.5 so we'd really almost stop nitrfiying in the first and start in the second and round and round we'd go. Certain things in wastewater just arent taught in school - I believe I have a paper in work from some PHd type who somehow actually measured DO on the floc scale basis although that happened to be in very recent times. I maintain that you will effectively shut down nitrfication at a DO above 2 ppm in a heavy mixed liquor because I have seen it happen and can make it happen.

So if one gets "hit" with a slug of ammonia its true that more lbs of air are needed to achieve this total oxidation. What is really happening though is that the rate of nitrfication needs to be increased by allowing all of the nitrfiers to hit on all 6 cylinders since we have a higher concentration to treat within the same HRT in the process. No, the "oxygen transfer" into the bulk fluid is not impeded by a higher ammonia concentration in the "slug". But to git-r-done within the HRT of the process we may need to jack up the DO so we are able to drive the DO throughout the MLSS to effectively maximise the rate of the nitrfication reaction. This is what I have observed in the field in FL, NC, VA, PA, DE, MD; IN;Il; other states could be different.

...and the bug knows best.

RE: How to lower ammonia level in an sbr plant

TerryF — Sun, 21 Oct 2007 04:07:37 GMT

I must have been away the day we were taught the relationship between floc size and MLSS , but maybe things work differently at higher elevations.

Last time i looked this was one of the principles behind oxidation ditches: Big tanks , lots of biomass (low F:M) but generally lower DOs which produces stable nitrogen removal performance.

At least i think thats how it works!!!

TerryF

RE: How to lower ammonia level in an sbr plant

bugwisperer — Sat, 20 Oct 2007 17:35:46 GMT

Laurie,

I read through this a bit quickly and it does appear that forum members are keying in on DO as a problem in basin 2. I would agree and add that depending on your mixed liquor conc a 2 to 3 to 4 ppm DO may not be adequate to effectively use all your nitrfiying organisms in the floc structure. If your MLSS is in the 4,000 to 5000 ppm range then your DO is going to have to be I'd say 4.3 to 4.5 ppm minimum. I'd shoot for 2.5 if your MLSS is 2500-3000. As you start to go from 3000 to 4000 and upwards your DO is going to have to go up to into the mid to high 3s. The reason is if you think of the floc structure as a tennis ball, most of the nitrfyng organisms have incorportated themselves deep within the tennis ball. So, until carbon is consumed by the heterotrophic organisms and this DO demand subsides, its a tough nut to crack trying to get DO into the center of the tennis ball to make the nitrifiers happy. The heterotrophs are opportunists and they suck up the DO on the surface of the tennis ball and act almost as a DO barrier to the poor nitrifiers. So if you have 2 or 2.5 parts DO in the bulk liquid you may still have 1 ppm or less on a microscopic level deep within the floc structure (tennis ball). The nitrifiers will be very discouraged. Under these circumstances you may need a 4 or 5 ppm DO in the bulk liquid to achieve a high enough driving force to achieve the mass transfer of DO deep into nitrifier town in the center of the ball. In a past life I did a little work with pure culture nitrifiers and was able to observe ammonia reduction versus DO concentration over time. DO was cyclicly applied - little aerator "on" at DO = 1.5 ppm and DO off at DO = 5 ppm. The sample of pure culture and ammonium chloride (and sodium bicarb and macro and micronutients) was mixed and ammonia conc was monitored via ammonia probe. It was interesting to note that ammonia reduction versus time was linear above 2.5 ppm in this particular sample of pure culture. At DO = 2.5 ppm the ammonia probe flatlined (no ammonia reduction) until the little aerator tripped back on at DO = 1.5 ppm and raised the DO. As soon as DO surpassed 2.5 ppm ammonia started to drop again linearly. The point I am trying to make is that the heavier the organism concentration the more difficult it is to insure that adequate DO (and mixing impacts as well to a degree) is available for 100% of the organisms in the process - to drive DO into the deep recesses of the floc structure in a "heavy" mixed liquor one needs to increase the driving force and mass transfer rate by increasing the bulk liquid DO. This why many times, particularly in the summertime, if ammonia starts to go up, wasting heavily will bring ammonia back down. Yes, we are decreasing the bugs in the process including our nitrifier friends but nitrifier numbers is not the problem. The problem is inadequate DO for the MLSS we have. Reducing the bug mass and in turn the endogenous demand allows the DO in the bulk fluid to come up, increase our driving force and mass transfer rate and greatly increases the mass of nitrfying organisms which have the DO they need to do their thing, even in consideration of the pounds we actually wasted from the process.

As a side note - I guess you have a total N limit or desire to have a mix cycle in the beginning to drive nitrate down so you dont get popping in your settle cycle. If your nitrate is very low in number 2 basin and ammonia is high you may want to temporarily elimiate your mix cycle and make it all react or aerate - ie, we dont need to mix to get rid of nitrate since we have none to begin with. Throw your time at aeration. You may only be doing a little bio-p action in the mix cycle.

I may have caught wind that your aeration system may be a jet system (big centrifugul pump with blower adding air in at the jet manifold in the basin). Sounds like a jet-tech SBR system maybe? Anyway, your manifold jet nozzles may have some clogs. You might want to compare the running amps on the pumps between basins - it may or may not provide a clue depending on whether the piping is largely similar.

If you have air piping flexibility to use basin #1 blower on basin #2 it might exclude the blower being an issue.

sounds like your alkalinity is OK. If you have 80 ppm going out the door you're good. Sodium bicarbonate is an excellent source of alkalinity and you cant overdo it relative to pH - you're only going to go to 8.2 or so at most even if you mess up and overdo it.

Mark

RE: How to lower ammonia level in an sbr plant

01780898 — Tue, 04 Sep 2007 23:24:27 GMT

It seems highly likely that you have a inadeqate flow and organic load split between the tanks. This will show up in a DO comparison between tanks. The tank with the higher Ammonia should show up lower DO. What is your sludge age in each tank? Otherwise it could be an inadequate air split between reactors.

You should also observe the decants in both tanks, to determine if you have bulking sludge and carryover of fluffy sludge in the decant. This will also reduce the sludge age, so if your high ammonia tank displays low DO, this would cause sludge bulking, which may cause bulking and carryover and even reducing conditions for nitrification. Do a 30 sludge settling test for each tank and calculate the SVI = 30 min settl (mL/L) / MLSS (g/L). Your sludge age needs to be approx 20 days to obtain adequate nitrification moderate winters (basin temp 10 deg C).

You also need to watch aeration times getting out of synch. If DO driven, then you need to check that the probes are calibrated and there is no slime film on them (eg the good tank). Add up the aeration hours per 24 hrs for both SBRs. If just timer related then this should ensure even aeration.

Regards

Grant H

RE: How to lower ammonia level in an sbr plant

LaurieH — Thu, 30 Aug 2007 15:57:33 GMT

Just my luck, the motive pump (mixing pump) in basin #1 has went down, so I will be forced to run off #2 basin by itself, which means constant filled settle or filled decant. I dont think things could get any worse. I guess it could, if I fail my DMR QA-27 study for EPA!!

Laurie

RE: How to lower ammonia level in an sbr plant

TerryF — Sun, 26 Aug 2007 06:25:15 GMT

Laurie,

Don't sweat it too much if things are not going well for you. I have seen some really good operators get into trouble with SBRs. They are not necessarily that difficult(although some are) but they sometimes challenge the conventional thought. But if they are not designed properly they will give you untold grief. Unfortunately many are not designed correctly and so you have to try to do the best you can with what you have.

With regards to the NH4 and the sludge blanket you need to waste less to have more nitrifiers to convert the ammonia to nitrate. If you waste too much it is possible to end up with no ammonia treatment capacity at all because the nitrifying bacteria are slow growing. If wasting at a rate where you turn over all the sludge in less than the time it takes for the nitrifiers to grow than you end up with no nitrifiers. You probably need to have an SRT , (solids retention time) of at least 15 days given your set up but probably longer and depending on the water temperature.

With regards to the pressure gauges we will have to make do with what you have. Try to get a reading on them when the blower is running and the basin are at the same level. For example when #1 is aerating during react and the water level is say 10 foot or 3.3 metres read the pressure gauge on the # 1 blower. Next time #2 basin is aerating try to get a reading when it is approximately the same level. If both blowers are performing the same and the aeration is performing the same the pressure will be about the same. As a rough rule of thumb for every 3 foot of water over your diffussers you should have about 1.4 psi blower pressure (or 1 metre for 10kpa if you prefer metric). If your numbers are well outside of this you have a problem , somewhere between a broken gauge , fouled diffussers or a worn out blower.

I understand the issue with the anoxic stage and the problem with timing for settle etc but I don't understand the blower configuration that has a blower for each basin yet they share a common air line. Normally you either have completely independant blowers for each basin or you have a common bank and you direct air to different basins with air valves.Is it possible to run two blowers together into basin 2 for a while to see what it does to the DO provided this does not exceed the maximum airflow rate for your aeration system?

Are you able to tell me the following info?

Average BOD or COD.

Average NH4 levels.

Quantity treated per day.

The depth of your tanks.

The type of diffussers. Coarse bubble or fine bubble.

What the capacity of you blower is ? What is on the name plate of the blowers and the motor driving them.

I can do some rough calculations for you to see how it all should work. Send me an email if you prefer.

Regards

TerryF

RE: How to lower ammonia level in an sbr plant

LaurieH — Sat, 25 Aug 2007 10:01:29 GMT

Terry,

I do only have one blower per basin and no way to increase the blowers output, (on & off only), the other problem I have is that both blowers share a common air line, therefore I find that if I increase my Aeration fill time, I will have one basin in Aer fill while the other basin is in react, and the basin that is in react is doing nothing (sitting still) because the basin that is in aer fill is taking all the air because it is at a lower level. So, I have had to increase my anoxic time to leave enough time for the react cycle to finish and go into settle. If that makes any sense. So I am basically confined to giving the basins the air they need in the react cycle. As for the the other question, I do operate on 4, 6hr cycles. My system is toltally flow proportional, with no controls to operate at a specific time, therefore the basins are constantly switching from peak flows to low flows. Also, I only have a psi guage on the discharge side of the blower, none on the intake side.

I also have a dumb question, the NH3 is produced by the microbes in the sludge blanket, therefore if I increase my waste time in that basin, shouldnt I be decreasing the ammonia levels just by decreasing the sludge(mlss) ? Or is it the other way around? I am totally new to a SBR plant, I'm more of a lab tech than an operator, but because I hold a WW liscense, I got thrown into this position, when the previous operator left.

Thanks, Laurie

RE: How to lower ammonia level in an sbr plant

TerryF — Fri, 24 Aug 2007 18:10:35 GMT

Laurie,

I agree with Bob. Check the blower inlet and discharge pressures. But also record the depth of the basins at the particular time because the discharge pressure will vary with depth. Try to compare the discharge pressures between the two basins at the same depth. If you have fine bubble diffussers (in particular) you could have fouling which is affectting the efficiency. Other diffussers could be affectted as well but fine bubbles are particularly bad.

From your description i am assumming that you have a blower for each basin with no DO control on the blowers and your "control" DO by time only or do you have a number of blowers with more blowers bought online at different parts of the cycle?

Do you operate on 4 , six hourly cycles per day per basin , with a fixed start time for each cycle or does the start time float based on volume , because this will have a bearing on what the loading is doing between the two basins?

I assume that when you say your micro looks bad you are saying there is little free swimming activity , no stalked cilitiates , amoebas etc. SBRs tend to favour certain types of protozoa but if you are seeing no activity this is likely to be a sign of low or poor DO. The type of protozoa you see will also depend on your SRT.

If you can do the following:

1) Increase your aerated times to increase the amount of oxygen supplied.

2) Increase your SRT a little at least.

3) Check your blowers etc as Bob and i have suggested.

4) Monitor the end of aeration ammonias with the decants.

It may take a week or two or more to fully recover but i would suspect that if you can the get on top of these items you will see some improvement relatively quickly.

Let me know about your blower and cycle configuration as above.

Regards

TerryF

RE: How to lower ammonia level in an sbr plant

LaurieH — Fri, 24 Aug 2007 17:09:42 GMT

Bob,

I will try your suggestions, with some help from the maintenance operator. I did raise the waste on #2, I was talking to another SBR operator from another town, she told me not to worry about wasting "out" the bugs, that they will come back around after adapting to the new conditions. I am happy to say that the changes I made to the cycles today have produced a longer react time, (50-60mins), and averaging about 100 to 115mins on aeration fill time. I hope this will raise my D.O. level up to a 2.0 by the end of the react cycle. If this doesnt work over the week-end, I may have to take the basin down to check my diffusers. If you have any more suggestions, please let me know, I feel real lost right now!

Thanks so Much,

Laurie

RE: How to lower ammonia level in an sbr plant

rwhitworth52 — Fri, 24 Aug 2007 16:46:30 GMT

Lauire,

You have enought alkanility. It looks, as Terry suggested, either the #2 SBR gets more organic matter or it gets less oxygen. If you read the electrical meter, read the numbers from right to left, so you know if it is pass or before the next digit (hard to explain), this will tell you the # of hours the blower ran. It will not tell you how many cubic feet of air was discharged.

Check the discharge and suction pressure on the blowers under same working conditions. Check the air filters on the blowers. You may want to have someone check the amp. draw on both blower under the same working conditions (same water depth in both SBR's). I would also drop the MLSS in #2, see if the oxygen level increases, and increase the aeration period, as long as possible.

Wastewater treatment is often diffucult to explain (art/science), so don't worry why one reactor works better than the other.

Good Luck

Bob

RE: How to lower ammonia level in an sbr plant

LaurieH — Fri, 24 Aug 2007 13:53:27 GMT

Terry,

My cycle durations are flow dependent. I have minimum aeration set on 140mins, full batch aeration on 165mins, max anoxic at 90mins., settle time at 70min. I did notice that I'm getting 50-60min in idle, I spoke with the sysyem programmer this morning, and he had me up the anoxic fill from 250min to 275min. he said that would force 25mins into react. My mlss for today is #1 2700 and #2 3100. But #2's micro-count looks low. I lowered my waste time to mins. on #2. #1 is at 4mins. I dont have a way to measure D.O. air volume, but I will try your suggestion. I'm not very good with electrical operations. I did measure my D.O. readings in each basin during react yesterday, #1 is great, .6 starting out and 4.5 at the end. #2 is not so good, .3 starting out and 1.5 at the end. I'm thinking about having someone check the blower on #2 for performance. Also I ran ammonia's this morning, and #2 has risen up 20.7 to 22.5 overnight. I dont know what I'm doing wrong, every book tells me to increase react time, but I dont get why #1 is ok, but #2 is so bad and not getting any better. I sure appreciate all the helpful info and suggestions though.

Thanks, Laurie

RE: How to lower ammonia level in an sbr plant

LaurieH — Fri, 24 Aug 2007 13:39:59 GMT

Bob,

your right, I was looking at the beginning ph. My Influent alkalinity is about 300mg/l, and effluent is 200mg/l. Are those sufficient levels?

Thanks,

Laurie

RE: How to lower ammonia level in an sbr plant

TerryF — Fri, 24 Aug 2007 04:36:44 GMT

LaurieH (8/23/2007)

Terry,

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

Laurie,

Don't try to keep the MLSS the same in the two basins what i was trying to gauge was whether they were equally loaded or not and it sounds like they may not be. Does your cycle step duration change with the volume of inflow , or is it preset. If you are able to preset i would move some time out of anoxic fill to aerated fill so that at a minimum you always get 140 minutes of aeration time (aerated fill plus react). I assume you are running four , six hour cycles a day. If they are based on volume it would appear that #2 maybe getting more load at least at times. It is also possible that even if it does not get more volume it may be getting a higher ammonia load.

Whilst you can convert ammonia to nitrate at low levels of DO , levels above about 1.5mg/l is best. Without knowing your loading or aeration details i would suggest that by the end of the aerated fill you should have DO somewhere about 0.5-1.0 mg/l and by the mid point of the react you should be getting close to 2 mg/l and be holding that through to the end of the aerated period. With those really short react periods you may have trouble unless you are getting up 1+ by the end of the aerated fill. These DOs will alter depending on your loading. One sbr plant i was involved ended up being so heavily loaded that unless the DOs were 4mg/l at the end of react ammonia removal was always poor.

Take a sample off the top of the basin soon after is finished aerating and you have a small amount of clear water on top to sample from and then compare the ammonia levels with the sample during decant. If the first is good and the second is a lot worse it will either point to ammonia(raw sewage) bleeding through from the inlet or other problems.

If you can also compare the volume of air supplied to the two basins. If no other means exist read the electrical meters when each basin starts and stops aerating. Over a few cycles it should give a comparison on the amount of energy being used to aerate each basin. More energy should mean more air unless you have a major defect somewhere.

Regards

TerryF

RE: How to lower ammonia level in an sbr plant

rwhitworth52 — Thu, 23 Aug 2007 19:07:12 GMT

Laurie,

Are those the end-point pH's or the Alkalinity in mg/l ?

RE: How to lower ammonia level in an sbr plant

LaurieH — Thu, 23 Aug 2007 16:36:17 GMT

Bob,

The citys H2O plant is surface water, I used SM 2320 B titration method for the testing.

Thanks, Laurie

RE: How to lower ammonia level in an sbr plant

rwhitworth52 — Thu, 23 Aug 2007 16:07:09 GMT

What method are you using to measure alkalinity ? Your readings are real low. Is the source water surface or ground ? Ground water is usually high in alkalinity, so if your source is ground water your alkalinity measurement is questionaly.

RE: How to lower ammonia level in an sbr plant

rwhitworth52 — Thu, 23 Aug 2007 16:05:00 GMT

Yes, its true is requires 7.2 parts of alkalinity to convert ammonia to nitrate. You can add a mixture of lime & water to increase the alkalinity (or any other caustic). The amount you will add depends on the amount of ammonia you need to convert will determine the amount of alkalinity needed. Using the volume of the aeration basin subtract the exsiting alkalinity from what you need and this should give you an idea on what to add. Start with a little less, measure the alkalinity and add more if needed. Be sure to mix the lime with water as it may form hard clumps by pour the dry material directly into a basin.

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

RE: How to lower ammonia level in an sbr plant

LaurieH — Thu, 23 Aug 2007 14:34:28 GMT

I'm running about 7.4 alkalinity in the Influent and 7.2 in the effluent on each basin.

Laurie

RE: How to lower ammonia level in an sbr plant

LaurieH — Thu, 23 Aug 2007 13:45:15 GMT

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

RE: How to lower ammonia level in an sbr plant

D Shulmister — Thu, 23 Aug 2007 12:36:20 GMT

Laurie

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

higher MLSS

longer react time

more air

sufficient alkalinity

RE: How to lower ammonia level in an sbr plant

LaurieH — Thu, 23 Aug 2007 11:27:35 GMT

Terry,

Thanks, Laurie

RE: How to lower ammonia level in an sbr plant

TerryF — Wed, 22 Aug 2007 17:16:08 GMT

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

RE: How to lower ammonia level in an sbr plant

LaurieH — Wed, 22 Aug 2007 14:46:21 GMT

Both basins are running between 6.9 and 7.2.

Laurie

RE: How to lower ammonia level in an sbr plant

dswolf — Wed, 22 Aug 2007 14:16:41 GMT

Do you have a recent pH reading in the SBR?

It should be in the 6.8 to 7.4 range for nitrification.

-David

How to lower ammonia level in an sbr plant

LaurieH — Wed, 22 Aug 2007 12:19:27 GMT

HELP!!!!!!!

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