Phosphorous Removal From Wastewater

The most common treatment mechanism for the removal of phosphorous from wastewater  involves the use of metal salt based coagulants:

M3+ + PO43-→ MPO4 ↓ (Where M is the metal ion)

A known amount of coagulant is applied to the wastewater.  A coagulated solid is formed and phosphate is precipitated out as a settled solid.  The amount of Phosphorous present is expressed as unit mass in kilogrammes, ie. mg/l phosphate x m3 daily flow.  Therefore an increase/decrease in wastewater phosphorous load would generally require an adjustment to the coagulant application rate in order to maintain the optimum dose concentration.

Typical products used for phosphorous removal include:

  • Aluminium Sulphate
  • Aluminium Chloride
  • Ferric Chloride
  • Ferric Sulphate
  • Ferrous Salts
  • Polymer blended with metal salts