The energy calculations based on the compressor improvement
scenarios focus on a centrifugal compressor delivering air in the
primary process of the illustrated system in . In this example
case, the operating range for the compressor is approximately
1.42–1.62 kg/s with the pressure ratio of 1.47. The operating range
varies according to the incoming waste water and the process conditions.
Based on the operation during 2013 and 2014, the monthly
average output for a single compressor is 1.52 kg/s. The pressure
ratio remains practically constant since the system pressure is
mainly dictated by the constant water level in the aeration tanks