Nutrient removal processes for low strength wastewater

For nutrient removal from low strength wastewater, biological nutrient remo val (BNR) processes available at present are not efficient due to the short age of organic carbon. By using the carbon source obtained from the degrada tion of return sludge, it was attempted to enhance the efficiency of denitr ification and phosphorus release. Based on its degradation mechanism, the E NR (Endogenous Nitrate Respiration) process was developed and compared with the conventional A(2)/O (Anaerobic/Anoxic/Aerobic), MUCT (Modified Univers ity of Cape Town) processes. In the experiment, the specific phosphorus rel ease rates of A(2)/O, MUCT, and ENR processes were 0.8, 2.3, and 2.6 mg PO4 -P g(2) MLVSS-h. As the nitrate concentration decreased below 3.0 mg NO2-N I-1 due to the endogenous nitrate respiration, the effluent nitrate of the ENR process was lower than the A(2)/O process and the MUCT process by 25% a nd 10% while the phosphorus removal efficiencies increased by 15% and 6%, r espectively. It was found that the ENR process was an effective and economi cal alternative for removing nutrient from low strength wastewater.