Phosphorous presents in different forms in Effluent Treatment Plant ETP and Sewage Treatment Plants STP soluble phosphorus is most common form. Typical methods for phosphorus removal are:

chemical precipitation

sedimentation

membrane filtration ( Reverse Osmosis )

and biological method depending on in which form phosphorus is present.

Biological removal of phosphorus is widely spread as it produces less sludge when compared with other methods.

In the conventional treatment process soluble phosphorous present in the wastewater is getting integrated with microbial biomass.

Enhanced biological phosphorus removal processes is suggested for wastewater treatment higher amount of phosphorus removal is possible.

There are certain factors affecting phosphorus removal via biological method including environmental and operational conditions such as

carbon source

COD/P ratio

temperature

pH

cations

dissolved oxygen

solid retention time

Carbon Source

Availability of carbon in the form of readily biodegradable carbonaceous oxygen demand affects phosphorus removal hence dosage of urea is recommended.

COD : Phosphorus Ratio

Recommended COD:P ratios between 10–20 mg-COD/mg phosphorus

Cations

Phosphorus itself is negatively charged hence addition of cation is recommended. Anion having three negative charges. Phosphorus cannot move across the cell membrane because of negatively charged , Its transportation across the microbial membrane need charge neutralization, neutralized ion is transported across the cell membrane. Hence cations increases Phosphorus removal

Dissolved Oxygen

DO concentrations between 2.5–3.0 mg/L is recommended, higher DO will affect the performance of phosphorus removal