reefclown
29-09-05, 15:52
The number of threads over the years is not massive, but the general method and concerns seem consistent.
This is a concerted effort to gather a general consensus on how they work and the benefits. Also to gather an understanding of the potential drawbacks and risks and how they can be managed. :idea:
What is a Sulphur Denitrator?
------------------------------
It's simply another potential method of eliminating/reducing nitrates, just like the use of a DSB or utilising macro export etc.
It can provide a source of calcium to the aquarium if coupled to a suitable calcium source
THE ARGUMENTS AND PERSONAL PREFERENCES OF USING ONE METHOD OVER ANOTHER I'LL TAKE AS GIVEN, WHAT WE ARE TRYING TO GET TO THE BOTTOM OFF IS THE METHOD, CHEMICAL AND BIOLOGICAL PROCESSES THE BENEFITS AND RISKS.
Here’s a bullet of some aspects that seem worth covering:
PROCESS OVERVIEW
--------
The reactor is initially tuned-in such that a low/no (anoxic, anaerobic) oxygen environment is created within the reactor, this allows specific bacteria to develop, these bacteria convert nitrates to nitrogen gas which is released to the environment, a by product of the reaction that takes place is the production of sulphuric acid, this acid is then passed over some calcium carbonate/aragonite media which results in the dissolution of calcium that gets added to the tank to supplement calcium levels.
METHOD
------
2 part reactor
As a start point lets take it as given that the reactor for the sake of argument is a
recirculating reactor like the korallin, but the only media being used is sulphur beads. i.e we have a water source entering the reactor, this circulates around the media and effluent drip rate is controlled via a tap.
The effluent is dripped into a bed of calcium carbonate prior to returning to the tank
We can look at the alternatives later.
BENEFITS
--------
1. NITRATE REDUCTION:
The bacteria in the sulphur filter use elemental sulphur and oxygen from the Nitration (NO3-), to feed. This is reduced over different intermediate stages to gaseous nitrogen, either in the water separates or as visible gas bubbles.
2 H2O + 5 S + 6 NO3- ---> 3 N2 + 5 SO4-- + 4 H+ (extract from Randy)
2. CALCIUM SUPPLEMENTATION
Randy takes a crack at how much calcium might be produced in the below
To estimate the magnitude of the effect, we start with a liberal estimate of how much
nitrate might be removed. Say 10 ppm of nitrate per week.
10 ppm nitrate = 0.16 mmole/L of nitrate
Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce
0.107 mmoles/L of H+ per week
How much calcium this could produce?
Assume that it takes one proton to dissolve one calcium carbonate:
CaCO3 + H+ ---> Ca++ + HCO3-
Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of
0.107 mmoles of Ca++ per week
since calcium weighs 40 mg/mmol, that's
4.3 ppm Ca++ per week.
For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day. Consequently, this method may not be especially useful for maintaining calcium and alkalinity levels. On the other hand, the acid produced will have a long term lowering effect on the alkalinity, so if you use it, watch the alkalinity.
RISKS
-----
1. ALKALINITY DEPLETION, LOWERING OF PH
rather like adding c02 to a calcium reactor,with this system, it is the same as adding sulphuric acid to the CaCO3 to get it to dissolve. Once the CaCO3 has dissolved and entered the main tank, the sulphuric acid cannot be blown off to the air like c02. So one is left with a very low pH.
Denitrification with sulphur in combination with calcium carbonate gives:
2NO3- + S + H2O + CaCO3 = CaSO4 + N2 (extract from Habib)
So calcium will increase relative to alkalinity.
extract from Randy
the total loss of alkalinity to the tank (assuming that nitrate is generated from foods and consumed by the reactor is on the order of 1 ppm per day) will be about 2.6 meq/L in 100 days.
In the presence of nitrate, the reaction produces sulphate ions
2 H2O + 5 S + 6 NO3- ---> 3 N2 + 5 SO4-- + 4 H+ (extract from Randy)
Sulphate is the second most common anion in seawater (after chloride), at about 2700 ppm.
2. RAISING SULPHATE TO UNNATURAL LEVELS:
extract from Randy:
My balancing of the equation gives:
6 NO3- + 5 S + 2 H2O ----> 3 N2 + 4 H+ + 5 SO4--
So, for every 6 moles of NO3- you get 5 moles of sulphate produced. In mass units, 1 ppm of nitrate gives 1.94 ppm of sulphate.
How much nitrate should one think will get reduced this way? I'm not sure. How much accumulates in a reef tank over time? 1 ppm per day? That would put the nitrate up 30 ppm per month.
At 1 ppm nitrate reduction per day, the sulphate will increase by about 2 ppm per day.
Normal seawater contains 2,710 ppm of sulphate.
So to get a boost of 10% in the normal sulphate concentration will take 136 days with no water changes at all.
How much change in sulphate is too much? I don't know, but let's use the variation between salt mixes as a guide to what is "OK".
In Craig's study, the sulphate ranged from 1440 ppm (Coralife; about 53% of seawater) to 3550 ppm (Seachem; about 31% more than seawater). Only 2 of the 8 salt mixes were within +/-10% of seawater. Most were substantially low. Instant Ocean was about 18% low, and could use a boost.
3. DENITRIFICATION REDUCTION THROUGH THE EFFECTS ON MOLYBDENUM
In oxic natural waters, molybdate is the thermodynamically stable form of molybdenum (Manheim and Landergren, 1978). Since the environmental abundance of sulphate in natural waters is thousands- to millions-fold higher than that of molybdenum, the inhibitory effect of sulphate can make molybdenum availability quite low. This may contribute to low rates of nitrogen fixation and nitrogen limitation in coastal marine ecosystems and in some saline lakes (Howarth and Cole, 1985; Howarth, Marino and Cole, 1988; Marino et al., 1990).
4. HYRDROGEN SULPHIDE POISONING :
As soon as the nitrate value approaches lower detection limit (thus close to zero), the bacteria no longer have sufficient nitrate as a source of oxygen and begin to use sulphate ions (SO42) as source of oxygen. With sufficiently nitrate they do not do this, since the "sulphate respiration" produces less energy. The problem is that at the end of the sulphate respiration hydrogen sulphide develops (H2S). (hugo)
5. EXCESS CALCIUM SUPPLEMENTATION:
In the second stage of a Sulphur filter there is Calcium carbonate to buffer the low pH created by the sulphur oxidation. The amount of dissolved calcium is depending on the denitrification rate in the first stage, lots of Nitrate removed means lots of Calcium in the water. In case you do not have such massive calcium consumers in your tank you may end up with much too high Ca level (jens)
--------------------------------------------------------------------------------------------
would be great if those that sell/use/manufacturer/have though about Sulphur Denitrators could share their valuable insights so that we can all get a better understanding and make more informed decisions. :bow:
Hopefully by the end of the thread it'll contain some useful info, in a format suitable for both general readers and those interested in more depth info. :)
so, any thoughts :D
oooh, links to some previous threads: :( :lol:
Ultimatereef
http://www.ultimatereef.net/forums/index.p...0946&hl=sulphur (http://www.ultimatereef.net/forums/index.php?showtopic=10946&hl=sulphur)
http://www.ultimatereef.net/forums/index.p...5292&hl=sulphur (http://www.ultimatereef.net/forums/index.php?showtopic=35292&hl=sulphur)
http://www.ultimatereef.net/forums/index.p...topic=13406&hl= (http://www.ultimatereef.net/forums/index.php?showtopic=13406&hl=)
http://www.ultimatereef.net/forums/index.p...topic=35292&hl= (http://www.ultimatereef.net/forums/index.php?showtopic=35292&hl=)
http://www.ultimatereef.net/forums/index.p...topic=7762&st=0 (http://www.ultimatereef.net/forums/index.php?showtopic=7762&st=0)
Reefcentral
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=140279&highlight=sulphur)
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=429833&highlight=sulphur)
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=433444&highlight=sulphur)
http://www.reefcentral.com/forums/showthre...ur&pagenumber=1 (http://www.reefcentral.com/forums/showthread.php?s=&threadid=626360&perpage=25&highlight=sulphur&pagenumber=1)
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=647776&highlight=sulphur)
Others
http://mars.reefkeepers.net/USHomeP...rDenitrator.htm
http://216.168.47.67/cis-fishnet/seascope/00SS1711.htm
http://www.reef.edu.au/asp_pages/secb.asp?FormNo=2
http://www-micro.msb.le.ac.uk/video/photosynthesis.html
http://216.239.59.104/search?q=cache:1Mijx...+bacteria&hl=en (http://216.239.59.104/search?q=cache:1MijxLxQ46AJ:www.ias.ac.in/currsci/feb102002/329.pdf+sulphur+bacteria&hl=en)
http://216.239.59.104/search?q=cache:wq6ws...+bacteria&hl=en (http://216.239.59.104/search?q=cache:wq6wsCA2qboJ:www.ias.ac.in/currsci/mar102004/639.pdf+sulphur+bacteria&hl=en)
http://dwb.unl.edu/Teacher/NSF/C11/C11Link...es/winograd.htm (http://dwb.unl.edu/Teacher/NSF/C11/C11Links/helios.bto.ed.ac.uk/bto/microbes/winograd.htm)
http://www.icsu-scope.org/downloadpubs/sco.../chapter04.html (http://www.icsu-scope.org/downloadpubs/scope48/chapter04.html)
This is a concerted effort to gather a general consensus on how they work and the benefits. Also to gather an understanding of the potential drawbacks and risks and how they can be managed. :idea:
What is a Sulphur Denitrator?
------------------------------
It's simply another potential method of eliminating/reducing nitrates, just like the use of a DSB or utilising macro export etc.
It can provide a source of calcium to the aquarium if coupled to a suitable calcium source
THE ARGUMENTS AND PERSONAL PREFERENCES OF USING ONE METHOD OVER ANOTHER I'LL TAKE AS GIVEN, WHAT WE ARE TRYING TO GET TO THE BOTTOM OFF IS THE METHOD, CHEMICAL AND BIOLOGICAL PROCESSES THE BENEFITS AND RISKS.
Here’s a bullet of some aspects that seem worth covering:
PROCESS OVERVIEW
--------
The reactor is initially tuned-in such that a low/no (anoxic, anaerobic) oxygen environment is created within the reactor, this allows specific bacteria to develop, these bacteria convert nitrates to nitrogen gas which is released to the environment, a by product of the reaction that takes place is the production of sulphuric acid, this acid is then passed over some calcium carbonate/aragonite media which results in the dissolution of calcium that gets added to the tank to supplement calcium levels.
METHOD
------
2 part reactor
As a start point lets take it as given that the reactor for the sake of argument is a
recirculating reactor like the korallin, but the only media being used is sulphur beads. i.e we have a water source entering the reactor, this circulates around the media and effluent drip rate is controlled via a tap.
The effluent is dripped into a bed of calcium carbonate prior to returning to the tank
We can look at the alternatives later.
BENEFITS
--------
1. NITRATE REDUCTION:
The bacteria in the sulphur filter use elemental sulphur and oxygen from the Nitration (NO3-), to feed. This is reduced over different intermediate stages to gaseous nitrogen, either in the water separates or as visible gas bubbles.
2 H2O + 5 S + 6 NO3- ---> 3 N2 + 5 SO4-- + 4 H+ (extract from Randy)
2. CALCIUM SUPPLEMENTATION
Randy takes a crack at how much calcium might be produced in the below
To estimate the magnitude of the effect, we start with a liberal estimate of how much
nitrate might be removed. Say 10 ppm of nitrate per week.
10 ppm nitrate = 0.16 mmole/L of nitrate
Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce
0.107 mmoles/L of H+ per week
How much calcium this could produce?
Assume that it takes one proton to dissolve one calcium carbonate:
CaCO3 + H+ ---> Ca++ + HCO3-
Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of
0.107 mmoles of Ca++ per week
since calcium weighs 40 mg/mmol, that's
4.3 ppm Ca++ per week.
For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day. Consequently, this method may not be especially useful for maintaining calcium and alkalinity levels. On the other hand, the acid produced will have a long term lowering effect on the alkalinity, so if you use it, watch the alkalinity.
RISKS
-----
1. ALKALINITY DEPLETION, LOWERING OF PH
rather like adding c02 to a calcium reactor,with this system, it is the same as adding sulphuric acid to the CaCO3 to get it to dissolve. Once the CaCO3 has dissolved and entered the main tank, the sulphuric acid cannot be blown off to the air like c02. So one is left with a very low pH.
Denitrification with sulphur in combination with calcium carbonate gives:
2NO3- + S + H2O + CaCO3 = CaSO4 + N2 (extract from Habib)
So calcium will increase relative to alkalinity.
extract from Randy
the total loss of alkalinity to the tank (assuming that nitrate is generated from foods and consumed by the reactor is on the order of 1 ppm per day) will be about 2.6 meq/L in 100 days.
In the presence of nitrate, the reaction produces sulphate ions
2 H2O + 5 S + 6 NO3- ---> 3 N2 + 5 SO4-- + 4 H+ (extract from Randy)
Sulphate is the second most common anion in seawater (after chloride), at about 2700 ppm.
2. RAISING SULPHATE TO UNNATURAL LEVELS:
extract from Randy:
My balancing of the equation gives:
6 NO3- + 5 S + 2 H2O ----> 3 N2 + 4 H+ + 5 SO4--
So, for every 6 moles of NO3- you get 5 moles of sulphate produced. In mass units, 1 ppm of nitrate gives 1.94 ppm of sulphate.
How much nitrate should one think will get reduced this way? I'm not sure. How much accumulates in a reef tank over time? 1 ppm per day? That would put the nitrate up 30 ppm per month.
At 1 ppm nitrate reduction per day, the sulphate will increase by about 2 ppm per day.
Normal seawater contains 2,710 ppm of sulphate.
So to get a boost of 10% in the normal sulphate concentration will take 136 days with no water changes at all.
How much change in sulphate is too much? I don't know, but let's use the variation between salt mixes as a guide to what is "OK".
In Craig's study, the sulphate ranged from 1440 ppm (Coralife; about 53% of seawater) to 3550 ppm (Seachem; about 31% more than seawater). Only 2 of the 8 salt mixes were within +/-10% of seawater. Most were substantially low. Instant Ocean was about 18% low, and could use a boost.
3. DENITRIFICATION REDUCTION THROUGH THE EFFECTS ON MOLYBDENUM
In oxic natural waters, molybdate is the thermodynamically stable form of molybdenum (Manheim and Landergren, 1978). Since the environmental abundance of sulphate in natural waters is thousands- to millions-fold higher than that of molybdenum, the inhibitory effect of sulphate can make molybdenum availability quite low. This may contribute to low rates of nitrogen fixation and nitrogen limitation in coastal marine ecosystems and in some saline lakes (Howarth and Cole, 1985; Howarth, Marino and Cole, 1988; Marino et al., 1990).
4. HYRDROGEN SULPHIDE POISONING :
As soon as the nitrate value approaches lower detection limit (thus close to zero), the bacteria no longer have sufficient nitrate as a source of oxygen and begin to use sulphate ions (SO42) as source of oxygen. With sufficiently nitrate they do not do this, since the "sulphate respiration" produces less energy. The problem is that at the end of the sulphate respiration hydrogen sulphide develops (H2S). (hugo)
5. EXCESS CALCIUM SUPPLEMENTATION:
In the second stage of a Sulphur filter there is Calcium carbonate to buffer the low pH created by the sulphur oxidation. The amount of dissolved calcium is depending on the denitrification rate in the first stage, lots of Nitrate removed means lots of Calcium in the water. In case you do not have such massive calcium consumers in your tank you may end up with much too high Ca level (jens)
--------------------------------------------------------------------------------------------
would be great if those that sell/use/manufacturer/have though about Sulphur Denitrators could share their valuable insights so that we can all get a better understanding and make more informed decisions. :bow:
Hopefully by the end of the thread it'll contain some useful info, in a format suitable for both general readers and those interested in more depth info. :)
so, any thoughts :D
oooh, links to some previous threads: :( :lol:
Ultimatereef
http://www.ultimatereef.net/forums/index.p...0946&hl=sulphur (http://www.ultimatereef.net/forums/index.php?showtopic=10946&hl=sulphur)
http://www.ultimatereef.net/forums/index.p...5292&hl=sulphur (http://www.ultimatereef.net/forums/index.php?showtopic=35292&hl=sulphur)
http://www.ultimatereef.net/forums/index.p...topic=13406&hl= (http://www.ultimatereef.net/forums/index.php?showtopic=13406&hl=)
http://www.ultimatereef.net/forums/index.p...topic=35292&hl= (http://www.ultimatereef.net/forums/index.php?showtopic=35292&hl=)
http://www.ultimatereef.net/forums/index.p...topic=7762&st=0 (http://www.ultimatereef.net/forums/index.php?showtopic=7762&st=0)
Reefcentral
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=140279&highlight=sulphur)
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=429833&highlight=sulphur)
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=433444&highlight=sulphur)
http://www.reefcentral.com/forums/showthre...ur&pagenumber=1 (http://www.reefcentral.com/forums/showthread.php?s=&threadid=626360&perpage=25&highlight=sulphur&pagenumber=1)
http://www.reefcentral.com/forums/showthre...ghlight=sulphur (http://www.reefcentral.com/forums/showthread.php?s=&threadid=647776&highlight=sulphur)
Others
http://mars.reefkeepers.net/USHomeP...rDenitrator.htm
http://216.168.47.67/cis-fishnet/seascope/00SS1711.htm
http://www.reef.edu.au/asp_pages/secb.asp?FormNo=2
http://www-micro.msb.le.ac.uk/video/photosynthesis.html
http://216.239.59.104/search?q=cache:1Mijx...+bacteria&hl=en (http://216.239.59.104/search?q=cache:1MijxLxQ46AJ:www.ias.ac.in/currsci/feb102002/329.pdf+sulphur+bacteria&hl=en)
http://216.239.59.104/search?q=cache:wq6ws...+bacteria&hl=en (http://216.239.59.104/search?q=cache:wq6wsCA2qboJ:www.ias.ac.in/currsci/mar102004/639.pdf+sulphur+bacteria&hl=en)
http://dwb.unl.edu/Teacher/NSF/C11/C11Link...es/winograd.htm (http://dwb.unl.edu/Teacher/NSF/C11/C11Links/helios.bto.ed.ac.uk/bto/microbes/winograd.htm)
http://www.icsu-scope.org/downloadpubs/sco.../chapter04.html (http://www.icsu-scope.org/downloadpubs/scope48/chapter04.html)