Process for removing nitrogen compounds from raw water

A process for the removal of nitrogen compounds from a supply of raw water comprising the biological denitrification of said supply of water in the presence of bacteria so as to produce a supply of water having a reduced nitrogen content and said bacteria containing cell-bound nitrogen, aeration of said supply of water having a reduced nitrogen content so as to release said cell-bound nitrogen in the form of ammonium ions substantially without the conversion of said ammonium ions into nitrate or nitrite ions, and precipitation of said ammonium ions from said supply of water in the form of struvite by treating said supply of water with magnesium ions and phosphate ions in a reactor and recirculating at least a portion of said substantially nitrogen-free supply of water withdrawn from said reactor back to said reactor whereby viable bacteria in said substantially nitrogen-free supply of water are added back to said reactor so as to produce a substantially nitrogen-free supply of water.