Reference no: EM133232508

The clever UCR student develops a side stream test reactor scheme to obtain µnm for nitrifying bacteria. It is indicated in the above sketch, which is not drawn to scale - the test reactor is only 4 liters compared to a 500 m3 aeration tank. Mixed liquor is pumped from the aeration tank at a constant rate to the aerated and mixed test reactor. Influent wastewater spiked with NH4-N is also fed to the test reactor feed stream at the same rate as the mixed liquor. This is flow Qf, and the total flow is QT (QT = 2Qf), as shown above. The hydraulic retention time of the test reactor is 6 hours. The total influent NH4-N concentration of the test reactor is 60 mg/L, and the test reactor effluent is 40 mg/L. By careful measurement of the SRT and nitrate production of the aeration tank, the plant engineer determines that the nitrifying bacteria concentration in the mixed liquor in the aeration tank is 40 mg VSS/L. Thus, the nitrifying bacteria concentration in the test reactor is 20 mg/L. The growth of autotrophic nitrifying bacteria is very slow and can be neglected in the test reactor. The reactor DO concentration is maintained at 4.0 mg/L during the testing, and the oxygen half-saturation constant KO is 0.5 mg/L. The temperature is at 20 oC, and the nitrifying bacteria half-saturation constant KS is 0.75 mg/L. The nitrifying bacteria yield coefficient (Y) is 0.10 g VSS/g NH4-N. What is the maximum specific growth rate for nitrification (µnm) in the test system?