De-nitrification by the use of Sulphur in a fluidized bed reactor.

[Belgian Anthias]

Orp

Orp

My goal is to make the flow as high as possible for easy management, to have the ability to decrease the flow when nitrate suddenly builds up.
ORP gives me an idea of the state of the effluent but not of the % of room in the reactor that is available for aneorobic bacteria to work? If for example the amount of NO3 increases will this show on ORP readings?
When adapting the volume of the reactor the same amount of nitrate can be removed at ORP readings between for example -150mv and -200mv? Is this correct? The bigger the reactor , the higher ORP reading will be for the same anearobic activity? Correct?

 

[Belgian Anthias]

Fluidized bed and ORP

Fluidized bed and ORP

This topic is NOT about the pro's and con's concerning a sulfur de-nitrator The use of a 1% reactor has proven to work satisfactory at a daily flow of minimum the systems volume/day. That is my goal. Others my do it differently. This topic is about the difference in managing a tube reactor and a fluidized reactor. I have no intention to open and close and restart the reactor for nitrate managing purposes.

ORP can not be used for a tube reactor because when some tunnelling occurs true the media readings will be erratic.

This topic is to find a way for good management of a fluidized bed reactor because we may assume that the reactor is self-regulating and is reproducing nitrate when flow becomes to high which effects PH and alkalinity more than it should. We can not assume nitrite will show us that flow is to high because it may not be detectable.
ORP readings may help to avoid this. As I use 1% reactors I can assume the reactor will be big enough to work at ORP readings of -100mv keeping a sufficient daily flow. But will reproduction of nitrate be avoided at that reading? How this can be tested?
I assume that in a nitrate balanced aqua without a reactor this process of nitrate reproduction may sometimes also go on and on without knowing.

How to combine Nitrate readings of the system and ORP readings of the effluent in reactor to manage the flow??

 

[Belgian Anthias]

Avoiding nitrate reproduction.

Avoiding nitrate reproduction.

I think the best thing to do is installing ORP reading and start from the workable readings that will show. But I will have no answer on the question if I am reproducing nitrate with a 1% reactor at a daily flow of minimum the systems volume when using a fluidized bed reactor. How will I know?

 

[Belgian Anthias]

How ORP will be influenced by other factors?

I think the best thing to do is installing ORP reading and start from the workable readings that will show. But I will have no answer on the question if I am reproducing nitrate with a 1% reactor at a daily flow of minimum the systems volume when using a fluidized bed reactor. How will I know?

Using ORP it must be possible to determine how much sulphur is needed to keep ORP at a low level, let us say - 250mv at the daily flow wanted, which will prevent flow becoming to high. But when nitrate builds and daily production is not removed any more I must eliminate the cause or increase the amount of sulphur to avoid the reactor becomes critical when decreasing the flow. The last solution I want to avoid.

May I conclude that ORP readings of -200mv are ideal giving a safe working range of +- 50 mv? This way a fluidized reactor can be build with the adequate amount of sulphur to have a minimal daily flow wanted and removing the daily produced Nitrate at 200mv ORP. This way the reactor can easily be managed by Nitrate readings of the system and ORP can be used to set alarms when flow adjustments will push the reactor out of the safe range and and can be used to limit the flow to become " out of range".

 

[Randy Holmes-Farley]

How ORP will be influenced by other factors?

Inside the reactor?

Mostly pH in the reactor and the ORP of the reef tank itself.

How to combine Nitrate readings of the system and ORP readings of the effluent in reactor to manage the flow??

I'm not sure I understand why you wouldn't just use ORP, which is the traditional way to do it.

If nitrate is increasing too much, ORP will likely rise as well in that reactor since nitrate is not being fully consumed, so maintaining ORP by flow should allow for variable consumption of nitrate.

Have you tried that and it didn't work well?

 

[CHSUB]

Using ORP with a sulfur reactor, some observation and details of my system.

325 g TV mixed reef with 20 fish. I use 2 gallons of sulfur, which is the full capacity of the reactor, ORP is measured in the reactor and the ORP controller turns the dosing pump on/off when the desired ORP is reached. I have on 2 occasions opened the reactor and added more sulfur with the idea of processing more water. I'm waiting on a reactor that can hold 4 gallons of sulfur as I believe this will better fit my needs. ORP of -230 gives clear effluent on a Salifert NO3 tester; -150 ORP processes more water, but shows slight pink on Salifert. I believe a 1% reactor is ideal, but the reactor only needs to processes about 10% of the systems water daily, ime. Using the ORP controller and peristaltic dosing pump has made the use of a sulfur reactor very simple and imo failsafe. DT no3 is currently maintained at 5 ppm, where previously it was 20 ppm or higher between WC. I have had problems with sps' paling/stn but that was before the reactor was installed and unfortunately the reactor has not solved that problem.

 

[Belgian Anthias]

Fluidized and ORP

Fluidized and ORP

How ORP will be influenced by other factors?

Inside the reactor?

Mostly pH in the reactor and the ORP of the reef tank itself.

How to combine Nitrate readings of the system and ORP readings of the effluent in reactor to manage the flow??

I'm not sure I understand why you wouldn't just use ORP, which is the traditional way to do it.

If nitrate is increasing too much, ORP will likely rise as well in that reactor since nitrate is not being fully consumed, so maintaining ORP by flow should allow for variable consumption of nitrate.

Have you tried that and it didn't work well?

B]I'm not sure I understand why you wouldn't just use ORP, which is the traditional way to do it.
[/B]

After incubation of the reactor one will want to increase the flow. As I want a daily flow of minimum the systems volume it depends of the amount of sulphur used when the point of reproduction of nitrate is reached. Can this point be determined by ORP reading? Increasing the flow will bring in more nitrate and more oxygen. ORP of the effluent will de-crease for example from -250mv to -150mv. If the reactor is not big enough it may be that -150mv can not be reached as oxygen is depleted by the re-production of nitrate. I do not know, I am just trying to develop a line of thinking. At some point the daily nitrate production will not be removed any more. When only ORP readings are used the possibility exists that this will not show, everything seems normal, no corrections will be made. It is even possible that when the point of nitrate re-production is reached ORP readings will decrease, showing that the flow may increase which will only show when at some point the nitrite and nitrate production stops and oxygen is not depleted any more.ORP will rise showing that the reactor is not working satisfactory any more. This is far to late! I do not know how much nitrite can be produced , re-producing nitrate using oxygen. Just to show my way of thinking!
Is it possible that in a fluidized bed more nitrate is re- produced than there is nitrate reduction without ORP will tell us?
So, trying to explain my line of thinking I also answered the question why I want to use the systems nitrate readings to adjust the flow instead of ORP.
As we use 1% reactors we know they work satisfactory at a minimum flow of the systems volume. It is a good base to start with ORP observations and find out what ORP can tell us.

If nitrate is increasing too much, ORP will likely rise as well in that reactor since nitrate is not being fully consumed, so maintaining ORP by flow should allow for variable consumption of nitrate.


Yes it should when using a tube reactor? I think, using a fluidized bed, for the reason I explained above, one may not be sure of that..

Have you tried that and it didn't work well?

We tried it on a tube reactor till it let us down. ORP was installed on a reactor who was in line for more than a year. Some day, readings where decreasing showing there was more oxygen, so we decreased the flow. A few days late again and so on. We should have known better. We had made our selves a critical reactor. We suspect water was tunnelling true the media.
Readings where correct but could not warn us for the bad working of the reactor because we misinterpreted the readings. We stopped using ORP because we had the experience it was not reliable. To avoid this we made the decision to start using fluidized bed reactors.
As far we had no problems because we stayed by using 1% reactors. We know fluidized bed reactors are easily managed but the yield of the reactor is lower than using a tube reactor. The reason must be because the reactor is self-regulating, finding its balance easily but removing less nitrate for the same volume of sulphur at the same flow. The reason can be the re-production of nitrate?
I try to find out how to minimise the con's of a fluidized bed reactor and find out the safe ORP range.

 

[Randy Holmes-Farley]

ORP of the effluent will de-crease for example from -250mv to -150mv.

Just to clarify future discussions, I refer to that as an increase in ORP.

Regardless of the actual ORP numbers involved, if the flow is too high there will be no consumption of the nitrate. ORP in the reactor should be a suitable indicator of whether the O2 is being used up, and so nitrate consumption can begin. If the ORP gets too low, that can mean that the nitrate is gone and you may be proceeding to perform other redox reactions that you may not prefer, or simply that the flow can be increased to process more nitrate if it is available.

IMO, CHSUB's method makes a lot of sense for this reason, as long as the equipment is reliable.

 

[Belgian Anthias]

Using ORP with a sulfur reactor, some observation and details of my system.

325 g TV mixed reef with 20 fish. I use 2 gallons of sulfur, which is the full capacity of the reactor, ORP is measured in the reactor and the ORP controller turns the dosing pump on/off when the desired ORP is reached. I have on 2 occasions opened the reactor and added more sulfur with the idea of processing more water. I'm waiting on a reactor that can hold 4 gallons of sulfur as I believe this will better fit my needs. ORP of -230 gives clear effluent on a Salifert NO3 tester; -150 ORP processes more water, but shows slight pink on Salifert. I believe a 1% reactor is ideal, but the reactor only needs to processes about 10% of the systems water daily, ime. Using the ORP controller and peristaltic dosing pump has made the use of a sulfur reactor very simple and imo failsafe. DT no3 is currently maintained at 5 ppm, where previously it was 20 ppm or higher between WC. I have had problems with sps' paling/stn but that was before the reactor was installed and unfortunately the reactor has not solved that problem.

Thank you for chairing these ORP readings.

I believe a 1% reactor is ideal, but the reactor only needs to processes about 10% of the systems water daily.


You are processing +- 14 gal/day for a 325 Gal system. It seems to me very low flow. System water will be processed in +- 25 day's. If the system Nitrate is stable there is very little daily production and probably this system can be managed without a de-nitrator. Be aware that the reactor is working close to its critical point.. Flow should be a lot higher. Normally 1Gal/h for 1gal sulphur and more. You have enough sulphur to manage this system. I would slowly increase the flow with little increments say once a day. As in this system the reactor has very little nitrate production to remove flow should be high.
I just wanted to add this. If you do this, please keep me informed about ORP readings and how the reactor responds.

Using the ORP controller and peristaltic dosing pump has made the use of a sulfur reactor very simple and imo failsaf


May I conclude that the flow true the reactor is regulated by a peristaltic pump?

 

[Belgian Anthias]

ORP of the effluent will de-crease for example from -250mv to -150mv.

Just to clarify future discussions, I refer to that as an increase in ORP.

Regardless of the actual ORP numbers involved, if the flow is too high there will be no consumption of the nitrate. ORP in the reactor should be a suitable indicator of whether the O2 is being used up, and so nitrate consumption can begin. If the ORP gets too low, that can mean that the nitrate is gone and you may be proceeding to perform other redox reactions that you may not prefer, or simply that the flow can be increased to process more nitrate if it is available.

IMO, CHSUB's method makes a lot of sense for this reason, as long as the equipment is reliable.

CHSUB's method may keep the reactor in a working range but for the moment I do not see how it can tell how to manage the reactor in line with the systems nitrate level.

The goal is to manage the reactor and find the balance without reproducing nitrate.

Let try to establish some basic rules:

Nitrate in the system builds up: ORP readings in reactor increases? at a to set point flow is de-creased, less oxygen less nitrate in the reactor, all nitrate may be reduced. ORP in reactor decreases. No action may be taken yet because we want the nitrate level in the aqua to decrease to its previous level.

Nitrate in the system lowers:
Less nitrate coming in., will ORP in the reactor decrease more if all nitrate was already removed? If YES, at a set point flow is increased, if NO there is a problem to solve.

Nitrate reaches the level wanted:
Flow must be adjusted to the daily amount of nitrate to reduce/day. Flow must be increased a little bit because it was set for lowering the nitrate level.
more nitrate, more oxygen is coming in, ORP will increase ?. At this point flow may not be decreased by ORP.

When high levels of nitrate had to be removed in a 1% reactor flow would be close to 1% and when reached the level wanted between 1ppm and 2ppm flow will be at least 5 times more. In a tube reactor this is good because we want a lot of flow true the media to prevent clogging. In a fluidized bed we have probably re-produced some nitrate? I do not think this is a lot because by the depletion of oxygen anaerobic balance will be found quickly.
Do I have to bother trying to solve this out?
Can ORP tell us when nitrate is reproduced? More nitrate ORP should increase But the production of nitrate takes place in the reactor and depletes free oxygen. less oxygen decreases ORP Will there be a difference in redox potential on which we can determine what happens? Do I have to bother!?

 

[CHSUB]

i think the part that you are missing is that the dosing pump is not running all the time, in fact, currently it is on for 5 minutes and off for about 3 minutes. i expect that when i get a bigger reactor, 4 gallons of sulfur, i will need a bigger dosing pump. i'm not sure this is the "best" way to run the reactor, but i'm sure it is the easiest. i ran it off a manifold counting drips and measuring effluent's no3 and that was a PIA.
when the reactor was "breaking in" the dosing pump would run for a few seconds and turn off for several hours. slowly over several weeks the dosing pump runs more and more. however, now as no3 has risen above 5 ppm the dosing pump is running less. currently i have a .5% reactor and think that a 1% reactor will work even better.

 

[Belgian Anthias]

i think the part that you are missing is that the dosing pump is not running all the time, in fact, currently it is on for 5 minutes and off for about 3 minutes. i expect that when i get a bigger reactor, 4 gallons of sulfur, i will need a bigger dosing pump. i'm not sure this is the "best" way to run the reactor, but i'm sure it is the easiest. i ran it off a manifold counting drips and measuring effluent's no3 and that was a PIA.
when the reactor was "breaking in" the dosing pump would run for a few seconds and turn off for several hours. slowly over several weeks the dosing pump runs more and more. however, now as no3 has risen above 5 ppm the dosing pump is running less. currently i have a .5% reactor and think that a 1% reactor will work even better.

I am amazed!. I send you a message to discus this.

 

[Randy Holmes-Farley]

Nitrate in the system lowers:
Less nitrate coming in., will ORP in the reactor decrease more if all nitrate was already removed? If YES, at a set point flow is increased, if NO there is a problem to solve.

ORP should decrease when nitrate is depleted. People normally adjust flow manually to prevent this from happening, but automatically could be fine too.

Nitrate in the system builds up: ORP readings in reactor increases? at a to set point flow is de-creased, less oxygen less nitrate in the reactor, all nitrate may be reduced. ORP in reactor decreases. No action may be taken yet because we want the nitrate level in the aqua to decrease to its previous level.

ORP in the reactor should increase when nitrate is in excess (not depleted). People normally adjust flow manually to prevent this from happening, but automatically could be fine too. Just as above.

While I've never used one, I think most people find a happy compromise on flow rate that works for them. Having a big more or less nitrate around on a day to day basis is not likely a big deal at all.

 

[tmz]

CHSUB, Thanks for sharing your technique. I think has good potential for controlling flow to maximize anaerobic activity ,provided the equipment stays on track. With more precise and timely control of flow related to nitrate levels in the reactor , aerobic activity could be minimized .
A few specifics I'd like to know:
What size peristaltic pump are you using? i.e, how much fluid does it move per minute?
Do you think and on/off control on a powerhead could work as well?
Where do you put the probe? Is there a port in you reactor ;or do you measure the effluent ORP some other way?
Does your reactor use a recirculating pump?
Do you valve input water ,effluent or both?

 

[RxMike]

Dentrification

Dentrification

Wow gentlemen,
I am embarassed to say i have nowhere close to your level of sophistication when it comes to running a denitrifier. I am currently running a GEO unit rated for my 500 gallon system. I use an aqualifter to feed the unit. I manually adjust flow rate of the effluent to control nitrates. I am not having great success keeping nitrates less than 20. I do have a heavily stocked reef with large fish. Any suggestions on how i can get nitrates below 10?

 

[bertoni]

The tank might need a bigger reactor if you're feeding a lot. The ratings for the reactors are based on some load assumptions. What's in your tank?

 

[RxMike]

dinitrifier

dinitrifier

Hello
I have 3 large angels..three large tangs(6 inches)..five wrasses
In a 300 gallon DT with 120 gallon fuge and 90 gallon sump

My skimmer ro 8000 xpe is constantly pulling out crud. Funny thing is I wad told this skimmer is too big for my system. Not an accurate statement. I was thinking that perhaps I needed another unit.

 

[bertoni]

Better skimming often helps, too. I'm not sure where I'd start. We don't have much useful information on how well skimmers work. You could ask in the equipment forum for some opinions.

 

[tmz]

Rx Mike.

I'm not familiar with the reactor you have or how you are running it.There is a thread in the diy forum that started in 2008 and is still; going. Lot's of folks share their experiences , techniques and the science of it there. Not all agree but it's still a good place to get an understanding of how to build and use one:

http://reefcentral.com/forums/showthread.php?t=1400576&page=28

These are a couple of my numerous posts on it, summarizing my experience with a 575 gallon system:

About a week to 10 days for 0 nitrate effluent, at a slow drip of 2 drops per second . About a month to get 0 nitrate at a faster drip of 9000 ml per hour. This was with 3 litres of sulfur in use and tank water starting at 80ppm or so in a 575 gallon system.


This is an update :

Started the nitrate reactor diy version with 3 liters of sulfur( carrib sea LSM) and five or six inches of seachem matrix media (the pumice stone type), on the evening of 1/07. I cycled it by dripping the effluent into a bucket for the first week using system water for input. Dripping into a bucket was to avoid putting effluent ammonia and nitrite into the system during cycling. I did open it once due to a failure of the reticulating pump about a week after starting so full cycling was delayed .Post #677

1/08 Reactor : ammonia /135ppm,No2 /0.1(deep purple on API test), NO3 /30ppm. System : NO3 /80ppm.

1/15 Reactor: ammonia /0, NO2/ 0, NO3 /<5ppm.

2/12 Reactor: NO3/ 0 at a flow rate of 9000ml per hour(55 gallons per day). System NO3/ 50ppm.

2/25 Reactor: NO3/ 0 at 9000ml per hour. System less than 5 ppm NO3. Hooray.

I want to once again thank dj the author of this tread for sharing the dyi design and making the application much easier and less expensive than it might have been. Post #678.


In the meantime if you have specific questions you can post them here or there if you prefer.

 

[Belgian Anthias]

Normal operation

Normal operation

'Can nitrate build up be avoided and how' is always the first question. As fish grow and animal live multiplies nitrate build up can not always be avoided.
The use of a sulphur de-nitrator can help to manage this.
After incubation of the reactor, started with a slow dripping effluent, flow must be adapted to the system. My experience is about 1% reactors which mean there is a quantity of sulfur of 1% of the systems volume.
Flow can slowly be increased till the effluent is not 0 nitrate any more. One can try to maintain 0 or 2ppm or more will also be OK as long as more than daily production is removed. After a two or tree days, the bacteria may need some time to find their balance again, effluent has returned to 0 or is maintained at the desired level. Than flow can be increased a bit more, and so on. Normally a flow of +- 1l/h for 1l sulfur can be reached. If not, there is a high daily nitrate production.
Using tube reactors nitrite may be noticed in the effluent when flow is increased to much at once. We could not find nitrite in the effluent of a fluidized bed reactor using the same procedure.
When after start up for example 20ppm has to be removed and one does not know the daily production of nitrate of the system, when nitrate reading goes down with, for making it easy, 0.5 ppm/day, reactor is removing 0.5 ppm + daily production/day. After a few weeks one may expect level has descended to 15 ppm. At the same flow less nitrate is coming in the reactor. At this moment the same amount of bacteria have to process less nitrate. To avoid some will try to find other means to survive flow is increased a little bid. More oxygen and more nitrate is coming in. More oxygen has to be depleted so less room for anaerobic activity, the increase of nitrate will help to fill up the space available with the bacteria we want. The balance is found again! If effluent is not 0 or a little above the previous desired amount, wait again two or tree days. If effluent nitrate readings are rising one should decrease the flow a little bit. As long as the effluent readings are a lot lower than the system's the reactor is working fine. If effluent is maintained for example at 2ppm that is fine to, as long system's nitrate level is descending we know we are removing more than the daily production.
When the system reaches the level desired the flow is minimum tree times higher than when we started to remove the 20 ppm. My system will have a flow now between 2% and 4% of the systems volume which means all the water in the system is passed true the reactor once a day.
This procedure will not work if there is not enough room in the reactor and not enough sulfur is used.
When system's nitrate decreases, flow true the reactor should be increased and visa versa. Do not wait till the desired level is reached before making corrections.
Once the desired level is reached and balance has been found small corrections have to be made let us say once a month.
Than the flow depends on the daily nitrate production. We had working reactors with a flow of more than 5% of the systems volume.
When reading this, one will understand why I am amazed reading how some systems are managed and working.
We use the sulfur de-nitrator as part of the biological system, not as a problem solver.