BADES ( biological anaerobic denitrification using elemental sulfur) is a natural process, not an invention. It takes place everywhere in the aquarium, everywhere a biofilm may grow. I simply use the word BADES reactor instead of sulfur denitrator or sulfur reactor because reactors using the BADES process must NOT be kept in an anoxic state. To point out the difference of management and the big difference in practical use. I use the name BADES reactor for sulfur reactors operated as it was intended by those who introduced BADES for nitrogen management in marine systems and used it in public marine aquarium systems for decades. On this and other fora one mainly speaks about sulfur denitrators with the advise to keep the reactor in an anoxic state. Why?
A carbon based reactor should be kept in an anoxic state to work , a BADES based reactor works fine at much higher flow rates, keeping DO above 0.5ppm in the effluent.
The big difference between methods using the BADES proces are: using a sulfur denitrator the flow is manged in function of the oxygen content ( oxygen content of influent is always the same, +- 6-7ppm) and the flow is limited to keep the reactor in an anoxic state. Using a BADES reactor the flow is managed in function of the nitrate level and the nitrate to remove daily, keeping the level steady or to lower the level, as needed.
We do advise if using a BADES reactor to keep the nitrogen content of the effluent above 0, measurable.
A practical example:
A 1000 l system. The nitrate level is 50ppm, the daily nitrate overproduction is +- 1ppm. The target nitrate level is between 1 and 2 ppm.
To remove 1ppm daily having 50ppm in the water a flow of only 20l daily is needed to remove 1ppm, a bit more flow to lower the level slowly, as it should. About
140 ppm DO is entered daily. The level descends reaching 20 ppm. To be able to remove the same daily nitrate production the flow is increased to reach 50l/daily just to maintain the level at 20ppm, a bit more to lower the level. At this point
+- 350ppm DO is entered daily. Assuming the reactor is big enough the level descends to 2 ppm by increasing the flow to
500l daily , flow needed to remove the same daily production of 1 ppm and keep the level steady at 2ppm. DO entered daily is increased to
+- 3500 ppm.To lower the level from 2ppm to 1 ppm the daily flow must double to
1000l daily needing a BOD ( biological oxygen demand) of
+-7000ppm daily to keep the reactor in an anoxic state ( <0.5ppmDO).
How this is done using a sulfur reactor with limited flow, sometimes equipped with flow regulation based on a negative ORP reading
?
This easily can be done by using BADES as intended by the developers of
the MAAO method ! Now we do not use tube reactors any more but MBR, moving bed reactors, eliminating the risk for tunneling.
If a high nitrate level is present we do advise to lower the level slowly. Sulfur denitrators are able to remove a high amount of nitrate having a high level available, creating a shock effect on nitrogen availability, alkalinity, pH, enz..
Using a BADES reactor the removal rate can be managed and adjusted to the daily nitrate overproduction to be remove daily, and a bit more if the level must decent. In case the removal rate does not only depends on the nitrate level available but mainly depends on the flow rate, DO entered and
BOD ( biological oxygen demand, the oxygen consumption rate due to aerobic activities)
see BADES bio-reactor.
We are not in a lab in where oxygen is removed by vacuum. Most research about denitrification capacity the results are retrieved using Lab tests in lab conditions.
We are using a flow true system where oxygen is removed by BOD!.
Longouet tested it for over 7 years before transforming it for practical use in public marine aquaria.
ref MB The MAAO system
A BADES reactor must
be big enough for the aerobic activities being able to remove enough oxygen for anaerobic processes needed to remove nitrate to take place. BADES takes place in oxygen transition zones, bacteria switching over from an aerobic pathway to an anaerobic pathway, NOT needing anoxic conditions. It all depends on BOD!!!!
In fact a good BADES reactor is a good remineralization filter, removing DOC, also producing nitrate, nitrate used up within the reactor. In such a reactor a lot of CO2 is produced. The effluent always must be aerated properly before entering the system! THIS IS VERY IMPORTANT!
Such a reactor must be BIG ENOUGH, at least 1% of the system volume, depending on the daily nitrogen production to remove daily. The minimal volume can be calculated and depends on the daily amount of nitrogen to be removed and the desired nitrate level to be maintained. A basic rule is 1% of system volume for 1ppm daily, making it possible to maintain a nitrate level of +- 2ppm. Longouet used 1% having to remove a level of 50ppm and 2% above 50ppm which finally is about the same, It also takes into account the volume needed for the aerobic activities needed to maintain a low nitrate level having the same production.
The capacity of a BADES based denitrator is mainly based on BOD, its capacity to consume oxygen
This means a normal bio can be managed to become a good BADES based denitrification system, this without using a closed reactor. One just has to add some elemental sulfur to the filter bed. ( in the case the filterbed is crushed shells)
An easy way for using BADES is using BADES-rolls in a refuge
see BADES columns.
ref: MB BADESS
One can use as many rolls as needed. The refuge is well aerated, as it was a normal bio.
We advise to use at least the same volume of calcium carbonate based media as volume of sulfur used.
How one can manage a sulfur based system if one does not know the basics of
the BADES process? .
I do not promote the use of BADES for removing a safely stored nitrogen reserve. There are better ways to do that, starting with creating a balance between reducers and producers, using
AAM or ANM, active nutrient and nitrogen management.
Removing safely stored nitrogen using a sulfur denitrator kept anoxic by limiting the flow , the method used may contain a lot more risks for the system as the presence of nitrate ever has been proven to be, certainly in the hands of someone not knowing how and why! Using BADES as it was intended, not keeping the reactor anoxic, will eliminate most if not all risks and limit the factor of human error.
The sulfur pellets must be technical grade and not contain any pollution.
How and why using BADES
All info about BADES and BADES Systems are available in the reference mentioned above.
I do
NOT promote the use of BADES for nitrogen management!!
Using BADES to remove harmless and safely stored usable nitrogen must only be considered if proper nitrogen management fails. In the case I do prefer the use of a BADES System considering other existing methods applicable for denitrification.
I do hope advise given is based on proper references, also if the references for some are incomprehensible. As long the adviser knows how and why, based on correct information or and personal experience based on that information.
We do provide all info in our wiki Makazi Baharini, BADESS. If the reader does not understand what it is all about, one should not use BADES. One can NOT use a BADES reactor as it was a automated device with an ON and OFF switch and a flow regulator valve, although a BADES reactor used properly will become self regulating, needing very little maintenance and adjustments once the desired level is reached. A good BADES reactor the same time also is a good bio-filter, all in the reactor produced nitrate can be removed. This must be taken in consideration because too much nitrogen may be exported. We do advise to keep the nitrate level at +- 1-2ppm, and reactor effluent nitrogen content measurable.
I do promote the use of AAM, active nutrient management, which includes nitrogen and carbon management, balancing producers and reducers, using bio-filter(s)
