Do you know how phosphorus removal bacteria work?

The principle of biological phosphorus removal in sewage is to artificially create biological excess phosphorus removal process to achieve controllable phosphorus removal effect.  The whole process must create anaerobic and aerobic alternating link to use the effect of phosphorus accumulating bacteria to achieve biological phosphorus removal process.

1) Phosphorus release under anaerobic conditions  

Facultative bacteria convert soluble BOD5 into low molecular volatile organic acid VFA by fermentation in the absence of dissolved oxygen or nitrate nitrogen.  These fermentative products or VFA from raw sewage are absorbed and transported to the cell to assimilate into intracellular carbon energy storage substance PHB. The required capacity is derived from the hydrolysis of polyphosphorus and the colysis of intracellular sugars, leading to the release of phosphate.

2) Phosphorus uptake under aerobic conditions  

Under aerobic conditions, the activity of P-accumulating bacteria was restored, and the amount of phosphorus exceeding the growth requirement was stored in the form of P-accumulating bacteria. Energy was generated through oxidative metabolism of PHB, which was used for P absorption and P synthesis. Energy was captured and stored in the form of high-energy bonds of polyphosphoric acid, and phosphate was removed from water.

3) Discharge of phosphorus-rich sludge  

The resulting phosphorus-rich sludge is discharged in the form of residual sludge, thereby removing phosphorus.  From the perspective of energy, phosphorus accumulating bacteria release phosphorus to obtain energy to absorb dissolved organic matter in wastewater under anaerobic conditions, and then dehydrolyze and absorb dissolved organic matter to obtain energy to absorb phosphorus under aerobic conditions.

The key to phosphorus removal is the setting of the anaerobic zone, which can absorb the low molecular weight matrix and quickly assimilate and store the fermentation products under short anaerobic conditions, that is, the anaerobic zone provides the competitive advantage for the phosphorus accumulation bacteria.

In this way, the phosphorus accumulating bacteria that can absorb a large amount of phosphorus can be selectively proliferated in the treatment system, and the purpose of phosphorus removal can be achieved by removing the excess sludge with high phosphorus content.  Another advantage of this selective proliferation is that it inhibits the proliferation of filamentous bacteria and avoids the possibility of producing sludge with poor precipitating performance. Therefore, the anaerobic/aerobic biological phosphorus removal process generally does not produce sludge bulking.