The finalisation of the Benchmark Simulation Model no. 2
has addressed some shortcomings in interim versions of
the model. With respect to the performance indices, the
weights used in the computation of the EQI were adjusted
to reflect ecological considerations. The over-prediction of
the aeration contribution in the total operating cost (OCI)
was addressed by using a new expression. The overloading
of the originally proposed plant was addressed by reducing
the N-load coming to the plant (to compensate for the
high N-content of the reject water) and increasing the
volume of the activated sludge tanks.