Optimal design for wastewater treatment

Although regulations regarding nitrogen discharge from wastewater treatment facilities become more and more stringent, it seems that existing steady state overall models for secondary wastewater treatment process do not contain effluent nitrogen concentration prediction. In this paper, a steady state mathematical overall model describing the activated sludge process with post-denitrification of secondary wastewater treatment is presented by considering the prediction of the effluent concentrations of the total nitrogen, ammonium nitrogen, biochemical oxygen demand and total suspended solids The optimum design problem is formulated as a nonlinear constrained optimization problem which minimizes the total cost and satisfies the overall mathematical model and constraints imposed for the effluent qualities. The optimization is carried out by using the constrained nonlinear sequential quadratic programming method to select optimal design. The effect of the uncertainty of the influent variables on the discharge effluent concentration for an optimally designed treatment system is presented as well.