After making thorough study on mechanism of nitrogen and phosphorus removal, it was found that biological removal of nitrogen and phosphorus is two independent and overlap biological processes. The overlap represents that denitrification, phosphorus uptake and nitrogen removal occur under anoxic condition due to contribution of phosphorus accumulating organisms. On basis of this conception, a new two-sludge treatment system (consists of two SBR system with different functions) was developed for biological denitrification and removal phosphorus. It gives a successful solution to the different requirement of nitrifying bacteria and PAOs on sludge age and the contradiction between denitrification and anaerobic phosphorus release from PAOs. The process has advantages of steady operation and good treatment effect, and is particularly suitable for treatment of wastewater with low BOD 5/ TP ratio.
China Water & Wastewater
nitrogen and phosphorus removal
phosphorus accumulating organisms