Measurements and modelling for sludge production minimization

The reduction of biological excess sludge by ozonation of a fraction of the sludge return flow is a well known technology, applied in many plants all over the world.
However, process optimization is not yet adequately documented in the literature.
It is not yet well known which operating parameters and/or characteristics of wastewater affect the relationship between ozone dose and reduction of excess sludge in a wastewater treatment plant where pure oxygen is used instead of air.

Planned activities within PerFORM WATER 2030

The experimental activities regarding measurements and modelling for sludge production minimization are part of the Biosolid valorization research line included in PerFORM WATER 2030. They are closely related to the experimental activities about sludge production minimization described here.
The experiments of ozonation on the sludge return flow and include the design and construction of an ozonation plant at San Giuliano West wastewater treatment plant, one line of which is appropriately converted to pure oxygen. This allows to evaluate the actual sludge production yield before and after applying the ozonation process and to simulate its behavior through modeling simulation.
The planned experimental activity include the comparison between the production of sludge in a plant fed with pure oxygen with and without ozonation of a fraction of the return sludge flow. The research will investigate the role of ozone concentration on process efficiency to verify whether there is a relationship between the ozone dose and the organic matter in wastewater.

Objectives and expected results

• Verification of the relationship between ozone dose and reduction of excess sludge production in a wastewater treatment plant with pure oxygen.

• Identification of the key parameters that determine the reduction of sludge production.

• Development of a simulation model for the prediction of reduction yields according to the operating procedures of the process.

Description of the activities

• Upgrade of one treatment line of the existing plant to convert it to feeding with pure oxygen instead of air.

• Design and construction of an ozonation plant on a fraction of recirculation sludge.

• Start-up, operation and monitoring of the plant under different operating conditions to optimize the process.

• Calibration and validation of a process simulation model.

Pilot site

The experimental activities will be located at San Giuliano Milanese West WWTP (Wastewater treatment plant) operated by CAP Group.
For further information, please refer to the specific web-page dedicated to demonstration sites of PerFORM WATER 2030.

Partners involved

S.I.A.D. S.p.A. has performed the design and upgrade of the plant, while DICA-AMB Department of Politecnico di Milano has provided the technical and scientific support for the experimental activities.
POLIMI DICA-AMB will also supervise the operation of the process and develop a simulation model in order to estimate the actual sludge production yield as a function of the characteristics of the wastewater and of the operating parameters of the process.