[Character of denitrifying phosphorus removal using MUCT process: operation at low C/N rate]

The effect of phosphorus uptake in the anaerobic zone of MUCT process fed with low C/N rate wastewater was studied. The experimental results shows that: (1) Because of the concentration of the COD is relative higher, nitrate is firstly used by the traditional denitrifying bacteria in the cycle sludge, and can not act as the electron acceptor for DPB. So the main action in the first anaerobic zone is phosphate release; (2) The DPB utilizes the PHB as the carbon stored in the anaerobic zone, and nitrate as electron acceptor to uptake phosphorus and the amount increases daily from 0.93 mg/L to 18 mg/L, and the anaerobic phosphorus rate stabilizes to 40 percent finally in the second anaerobic zone; (3) The ineffective phosphorus release process occurs in the third anaerobic zone because the lower nitrate and COD concentration,and phosphate release amount is from 0.27 to 3 mg/L; (4) The COD, TN, TP removal rates are higher and the TP and TN concentration in effluent is below 10 mg/L and 0.9 mg/L respectively.