BIOLOGISCHE WASSERBEHANDLUNG, WELCHE POST- DENITRIFIKATION UND EINEN MEMBRANFILTER UMFASST

A process for treating water to remove nitrogen to required low treatment level, using post-denitrification mechanisms without addition of carbon sources, and characterized in that it comprises the steps of (h) providing an aerobic zone (1) having an aerobic mixed liquor having organisms which degrade the carbonaceous matter and nitrify the aerobic mixed liquor; (ii) providing an anoxic zone (2) having an anoxic mixid liquor having organisms which denitrify the anoxic mixed liquor without any need of additional carbon sources; (j) flowing water to be treated into said aerobic zone (1); (k) flowing aerobic mixed liquor into said anoxic zone (2); (l) contacting anoxic mixed liquor against the feed side of a membrane filter (3); (m) producing a treated effluent lean in nitrogen, BOD, COD suspended solids and organisms from a permeate side of the membrane filter (3); and (n) removing some or all of the material rejected by the membrane filter (3) from the process, wherein the steps above are performed substantially continuously and substantially simultaneously.