Patent ID: 7722768

Claim:
A process for the simultaneous removal of biochemical oxygen demand (BOD) and phosphate from a liquid containing ammonium, BOD, phosphate and magnesium, the process comprising: a) feeding the liquid to a reactor containing a BOD-oxidising biomass; b) ensuring that the liquid in the reactor contains an excess to stoichiometry of ammonium and magnesium relative to phosphate, wherein the stoichiometry is related to the stoichiometry of struvite; d) aerobically oxidising at least part of the BOD in the reactor; e) adjusting the pH of the liquid in the reactor to a value of 7.5-11; f) forming solid material in the reactor to form reactor effluent which exits from said reactor, the solid material comprising struvite; g) separating at least part of the solid material from the reactor effluent; h) returning a part of the solid material to the reactor; and i) maintaining a biomass retention time of the biomass in the reactor such that nitrification of ammonium in the reactor is 25% or below.