Acrotrdco
New member
I've posted this on another forum and I'd like to share / discuss this idea with you guys here.
I've got a link to this PhD thesis paper from the National Central University of Taiwan, it's written in Traditional Chinese, but the abstract is in English.
http://thesis.lib.ncu.edu.tw/ETD-db/ETD-search-c/view_etd?URN=86346005
I've tried to locate similar papers in English but so far I couldn't find any of them that points out this idea in such clarity as this one, this paper is almost like the "manual" of how zeolite system works.
Basically in the paper it documents how Sequential Batch Biofilm Reactor system (SBBR) is utilizing PAO (Polyphosphate Accumulating Organisms), through alternating between the aerobic/anaerobic phases, to accmulate/consume PHA (Polyhydroxyalkanoates) to remove phosphorus from the water column.
If you've noticed, zeolite systems (such as KZ ZEOvit) also requires a 3 hours on/off flow to alternate between the aerobic/anaerobic phases, probably to achieve similar results from a SBBR system.
Images from the paper:
And part of the abstract:
...Sequential Batch Biofilm Reactor system (SBBR) is effective in removing phosphorus. The storage and release of intracellular inclusions, especially PHAs and poly-P, would be an important factor for phosphorus removal. Under different operating conditions, total phosphorus removal was always determined by accumulation of PHAs and phosphorus release under the anaerobic phase. The PHAs accumulation under the anaerobic phase was always in proportion to the biofilm phosphorus content under the aerobic condition. The result shows PAOs activity was closely related to PHAs accumulation. However, the PHAs accumulation under the anaerobic phase would be dependent on the hydrolysis of the complex carbon source into short chain fatty acids. The effect of the An/Ox time ratio on TP removal was significant. Shorter anaerobic time would result in insufficient phosphorus release and greater time would result in inactive PAOs. The appropriate An/Ox time ratio was suggested as 1/2 and appropriate duration time was suggested as 6-8 hours.
In the anaerobic phase, the main activity of COD uptake occurs in initial 30 minutes. However, activity of phosphorus release occurs in 30-60 minutes and this phenomenon is more significant for initial substrate with higher concentrations due to the delay effect of mass transfer of adsorbed COD. The PHAs accumulation and phosphorus release share a similar trend. Since PHAs' demand per released phosphorus is independent of the initial COD, the enhancement of PHAs' accumulation would benefit phosphorus release. In the biofilm's system, the only requirement is to have sufficient and simple initial substrate and it would result in sufficient PHAs' accumulation for phosphorus release. In the aerobic phase, because poly-P storage's capability is always not saturated, PAOs could uptake excess PO43-. In other words, the limitation of TP removal is always caused by anaerobic phase, not the aerobic phase.
===================
In other words, the zeolites used in these zeolite systems, are nothing more than "bacteria housing", since Randy already pointed out that the NH4 binding capabilities of zeolites are rapidly depleted after a few hours and there's no proofs that zeolites will continue to exchange ions in a marine environment.
Which means, I'd assume one could even use GAC or even bioballs instead of zeolites, and would still achieve similar results.
===================
On a side note, since biopellets are mainly PHA (speculated to be the main ingredient of NP Biopellets), I'd assume there's no need for PAO's to accumlate anymore PHA therefore the anaerobic phase (required to build up PHA) is not needed, all the PAO need to do is to consume the PHA from the pellets and uptake PO4, this's probably how the NP biopellets works on controlling N and P.
Reference:
http://www.reefcentral.com/forums/showthread.php?p=17432897
I've got a link to this PhD thesis paper from the National Central University of Taiwan, it's written in Traditional Chinese, but the abstract is in English.
http://thesis.lib.ncu.edu.tw/ETD-db/ETD-search-c/view_etd?URN=86346005
I've tried to locate similar papers in English but so far I couldn't find any of them that points out this idea in such clarity as this one, this paper is almost like the "manual" of how zeolite system works.
Basically in the paper it documents how Sequential Batch Biofilm Reactor system (SBBR) is utilizing PAO (Polyphosphate Accumulating Organisms), through alternating between the aerobic/anaerobic phases, to accmulate/consume PHA (Polyhydroxyalkanoates) to remove phosphorus from the water column.
If you've noticed, zeolite systems (such as KZ ZEOvit) also requires a 3 hours on/off flow to alternate between the aerobic/anaerobic phases, probably to achieve similar results from a SBBR system.
Images from the paper:
And part of the abstract:
...Sequential Batch Biofilm Reactor system (SBBR) is effective in removing phosphorus. The storage and release of intracellular inclusions, especially PHAs and poly-P, would be an important factor for phosphorus removal. Under different operating conditions, total phosphorus removal was always determined by accumulation of PHAs and phosphorus release under the anaerobic phase. The PHAs accumulation under the anaerobic phase was always in proportion to the biofilm phosphorus content under the aerobic condition. The result shows PAOs activity was closely related to PHAs accumulation. However, the PHAs accumulation under the anaerobic phase would be dependent on the hydrolysis of the complex carbon source into short chain fatty acids. The effect of the An/Ox time ratio on TP removal was significant. Shorter anaerobic time would result in insufficient phosphorus release and greater time would result in inactive PAOs. The appropriate An/Ox time ratio was suggested as 1/2 and appropriate duration time was suggested as 6-8 hours.
In the anaerobic phase, the main activity of COD uptake occurs in initial 30 minutes. However, activity of phosphorus release occurs in 30-60 minutes and this phenomenon is more significant for initial substrate with higher concentrations due to the delay effect of mass transfer of adsorbed COD. The PHAs accumulation and phosphorus release share a similar trend. Since PHAs' demand per released phosphorus is independent of the initial COD, the enhancement of PHAs' accumulation would benefit phosphorus release. In the biofilm's system, the only requirement is to have sufficient and simple initial substrate and it would result in sufficient PHAs' accumulation for phosphorus release. In the aerobic phase, because poly-P storage's capability is always not saturated, PAOs could uptake excess PO43-. In other words, the limitation of TP removal is always caused by anaerobic phase, not the aerobic phase.
===================
In other words, the zeolites used in these zeolite systems, are nothing more than "bacteria housing", since Randy already pointed out that the NH4 binding capabilities of zeolites are rapidly depleted after a few hours and there's no proofs that zeolites will continue to exchange ions in a marine environment.
Which means, I'd assume one could even use GAC or even bioballs instead of zeolites, and would still achieve similar results.
===================
On a side note, since biopellets are mainly PHA (speculated to be the main ingredient of NP Biopellets), I'd assume there's no need for PAO's to accumlate anymore PHA therefore the anaerobic phase (required to build up PHA) is not needed, all the PAO need to do is to consume the PHA from the pellets and uptake PO4, this's probably how the NP biopellets works on controlling N and P.
Reference:
http://www.reefcentral.com/forums/showthread.php?p=17432897
