Minimisation of Nitrogen Discharges for Small-Size Wastewater Treatment Plants

The use of dynamic optimisation methods to provide optimal operating strategies for small size wastewater treatment plants is investigated. The optimisation objective is to determine the aeration profile (air-on and air-off periods) which minimise the concentration of total nitrogen that is discharged over a specified time horizon. Long term effects of the optimisation are considered; it is shown that appreciable reductions of total nitrogen residual concentration of about 30% can be achieved with respect to usual operating modes, along with large reductions of aeration time.