Long-term simulation of the activated sludge process at the Hanover-Gümmerwald pilot WWTP

Abstract

The aim of this study was to obtain a validated model, consisting of the Activated Sludge Model No. 3 (ASM3) and the EAWAG bio-P module, which could be used as a decision tool for estimating the maximum allowable peak flow to wastewater treatment plants during stormwater conditions. The databases used for simulations originated from the Hanover-Gümmerwald pilot plant subjected to a series of controlled, short-term hydraulic shock loading experiments. The continuous influent wastewater composition was generated using on-line measurements of only three parameters (COD, N-NH 4 +, P-PO 4 3−). Model predictions were compared with on-line data from different locations in the activated sludge system including the aerobic zone (concentrations of N-NH 4 +, N-NO 3 −) and secondary effluent (concentrations of P-PO 4 3−). The simulations confirmed experimental results concerning the capabilities of the system for handling increased flows during stormwater events. No (or minor) peaks of N-NH 4 + were predicted for the line with the double dry weather flowrate, whereas peaks of N-NH 4 + at the line with the quadruple dry weather flowrate were normally exceeding 8 g N m −3 (similar to the observations).