Why recover phosphorus for recycling, and how?

The removal of phosphorus from municipal waste waters prior to their discharge into the receiving waters is practised widely and a number of effective and reliable techniques can be employed. In almost all of these, the phosphorus is removed from the aqueous phase into the sludge phase (either as a precipitated metal salt or as a component of the sludge biomass) along with other solids. There are, however, a growing number of techniques, some at a laboratory stage, a few in full scale operation where the phosphorus is removed in the form of a simple inorganic phosphate salt which may have utility for recycling in industrial applications. The potential for recovery and recycling of phosphorus is reviewed from both a historical and a modem industrial perspective.