In this paper

the simulation of external carbon addition was studied in the continuous flow anoxic/oxic(A/O) nitrogen removal process for domestic wastewater of low carbon∶nitrogen(C/N). It is difficult to develop a parametric model for the complex non-linear relationship among additional carbon dosage

total recycling rate and effluent total nitrogen concentration in a treatment system

which makes it hard to turn the control strategies into reality. Aiming at this problem

back-propagation neural network(BPNN) was introduced into the research.A non-parametric model was developed by the training of BPNN with the experimental data. The external carbon dosage could be optimized with the model based on neural network. It provided an alternative way to the realization of on-line optimal control of a wastewater treatment system.