Dissolved oxygen PWM control and oxygen uptake rate estimation using Kalman Filter in activated sludge systems

The measurement and utilization of the oxygen uptake rate (OUR), or respiration rate, is very important in biological wastewater treatment process. It provides information about the biological activity and can indicate the presence of the toxic elements able to corrupt the system. An alternative to the lack of OUR sensors is to use computer codes as software sensors for the estimation of respirometric activity, based on dissolved oxygen (DO) measurements. In this paper the OUR is estimated using Kalman Filter as a software sensor and the DO concentration is controlled by aerators of on-off type triggered by pulse wide modulation. Simulation and experimental estimations are performed on a bench scale aerobic reactor.