Removal of ammoniacal nitrogen from BOD sorption zones

摘要

The known operation of an activated sludge system to afford a sludge having rapid settling characteristics and contg. an activated biomass species in which: (a) a mixed liq. is formed in a BOD sorption zone by mixing an activated biomass with a soluble BOD5 and NH3 contg. waste water influent such that at least 25% of the soluble BOD5 is sorbed by the biomass; (b) the BOD5 (including at least part of the biomass-sorbed material) is oxidised in an oxidn. zone with an oxidising agent (at least 30% BOD5 oxidised); (c) the oxidised mixed liq. is settled in a settling zone to give a supernatant and a dense sludge contg. activated bioasss (at least a portion of which is recycled to the BOD sorption zone), is improved by reducing the NH3-N concn. of the mixed liq. in the oxidn. zone so that the NH3-N concn. in the mixed liq. leaving the zone is less than 0.3 ppm. In addn., the overall F/M ratio is kept not less than 0.05.