[QUOTE=Spakase;5539873]Great thread.
Thanks. I will try my best in answering your questions.
Can I ask a few questions:
1. Are bioballs better than rings or will any filter material, including sponge do?
The anaerobes we are cultivating are of biofilm type. Biofilm is the structural appearance of bacterial mass (biomass) on the surface of the reactor support matrix (biomedia). Ideally, the biofilm should be a consistent and uniform accumulation of bacterial solids that appear like a gelatinous and slime-like layer that can be put into contact with the water being treated for the removal of nitrate contamination. As such, media with tiny pores (ceramic ring, biohome, fine pores sponge...etc) are not suitable. Another alternative is Jap Mat or super large pores sponge.
2. Is there a necessity for some space in the Denitrator, ie not to fill up with material to the brim? What's the reason?
Not really. I do it mainly for faciltating easier closing of the reactor cover as the pump and piping system are located internally.
3. Heterotrophic bacteria - how did they get into the Denitrator? Besides heterotrophic bacteria, will there be other forms of bacteria present that are harmful to fishes?
The formation of the bacteria is the same as the aerobe species in nitrification. As long as the parameter is ideal (not for us but the bacteria itself), the bacteria will begin to cultivate.
There are basically 3 types of anaerobic bacteria.
- Obligate anaerobes will die when exposed to atmospheric levels of oxygen.
- Facultative anaerobes can use oxygen when it is present.
- Aerotolerant organisms can survive in the presence of oxygen, but they are anaerobic because they do not use oxygen as a terminal electron acceptor.
There many strains and some are not .....shall we call it "not so nice?". I will discuss about this later.
4. All anaerobic bacteria in the Denitrator will die immediately upon exposure to oxygen - is this true? Can some survive and find it's way back into the tank?
It depends on the level of oxygen and duration of exposure. Remember about the aerotolerant and facultative anaerobe? It will find its way to the tank if you allows it to be but it will not survive.
5. Is it a good idea to feed the denitrator with aerobic bb?
How shall I explain this? In carbon-based denitrator, aerobic bb is cultivated to reduce the DO level inside the reactor. It actually co-exist together with the anaerobic bacteria.
6. What is the output from the Denitrator? Is it a good idea to fix a UV to the Denitrator's output to kill any bacteria exiting from the Denitrator, as an alternative, say if one wants to be certain none gets back to the tank?
Denitrification requires a controlled environment to work which is the same nitrification. The difference is the working area for denitrification is very small as compare to nitrification. This means that the flowrate has to be relative to the size of the anaerobe community and denitrification process.
Yes. I would advocate some measures to treat the denitrator's output. UVC and ozoniser are some examples. This is to prevent undesirable "pathogen" of releasing to the tank. I will touch more on this area later.
7. Besides bacteria, what else can be found in the Denitrator's output?
Same question as in 4 and 6. There are presence of excess biological solids being discharged by the denitrator or fouling resulting from extraneous reactions including sulfate reduction to produce traces of hydrogen sulfide. Fouling in this case also is referred to as “biofouling.”
8. Why is it important for the control valve to be located at the Denitrator's input?
One main resultant component in denitrification is nitrogen gas but there are also others due to biofouling too. If the valve is located at the output to controll the flowrate, the reactor risk pressure build-up and will result in leaking.
9. What is known to kill anaerobic bacteria?
O2, O3, light, UVC, chlorine, hydorgen peroxide...etc. .
Whew!