Sewage nitrogen and phosphorus removal - separates nitrogen in a main flow and strips out the phosphor in a side flow

摘要

To apply a continuous biochemical removal action on nitrogen and phosphorus from sewage, it is passed directly into a denitrification stage and the nitrogen is removed in a main stream through successive stages for denitrification, nitrification and sepn. The phosphorus is sepd. into a side stream where the activated sludge sepd. at the first stage is used for phosphate stripping after passing through an anaerobic stage in a second solids sepn. The sepd. sludge is returned as a sludge generally free of phosphate to the denitrification, while the phosphate-enriched water portion is passed to phosphate pptn. followed by sepn. of an assessable phosphate sludge. The activated sludge concn. is more than 4.5 kg/m3 in the denitrification, nitrification and phosphate stripping stages. The oxygen supply during nitrification is at a raised pressure of at least 1 bar. During phosphate stripping, a fatty acid material is added if there if a reduced fatty acid content. USE/ADVANTAGE - The method is for the continuous sepn. of nitrogen and phosphorus from sewage. The system does not require a number of large vol. vessels, and gives recovery of useful matter.