Evaluating upgrade possibilities of activated sludge wastewater treatment plants utilizing biofilm-based treatment technologies – an experimental study at the South Pest WWTP

As more and more wastewater treatment plants (WWTPs) arrive to a point in their lifecycles when their original capacities are not sufficient anymore, the demand for good WWTP retrofitting solutions becomes increasingly critical. One of the typical problems is the suspended solids overload of secondary clarifiers, which is one of the main concerns at the South Pest WWTP as well. Pilot scale studies were carried out at the WWTP with a biofilm based technology applying biofilm carriers imitating plant root structures in order to characterize the potentials of clarifier TSS load reduction while maintaining the existing biodegradation performance of the activated sludge stage. The research demonstrated that the clarifier load can be reduced by more than 90%, while the original biodegradation performance of the system does not decrease. In addition to this, it was demonstrated that the biomass amount in the reactors can be increased substantially opening potentials for further biodegradation capacity.