November 30, 2017

Dynamic process model to predict membrane fouling

Ramboll is developing a new, dynamic process model to predict membrane fouling at Finland’s largest MBR based water & wastewater treatment facility.

Many modern wastewater treatment facilities have started implementing the Membrane Bioreactor (MBR) technology; an activated sludge process where gravity separation of solids is replaced by membrane filtration.

The MBR technology is one of the most important recent technological advances in terms of biological wastewater treatment; but nevertheless, the technology also faces some threats and challenges.

“Membrane Fouling is one of the main challenges for MBR based waste water treatment, as it significantly reduces membrane performances and membrane lifespan, leading to an increase in maintenance and operating costs,” says Eppu Väänänen, BEng and Designer in Ramboll’s international water division.

Membrane Fouling is a process whereby a solution or a particle is deposited on a membrane surface or in membrane pores in a process such as in a Membrane bioreactor, so that the membrane's performance is degraded.

A dynamic process model in the bedrock

The Water utility in Mikkeli, a town and municipality in the southern part of Finland, is currently establishing a new and modern wastewater treatment facility, the Metsä-Sairila Wastewater Treatment Plant, literally carved into the bedrock. The new facility is going to be the largest of its kind in Finland and will be 100 % based on the MBR technology.

Membrane fouling is hence a relevant concern for Mikkeli Utility, and it has therefore joined Ramboll and the Lappeenranta University of Technology for a common attempt to limit problems and performance reduction caused by the fouling. The project is led by Eppu Väänänen.

“We are building a dynamic process model on a new flexible software platform developed by Dynamita Ltd to better understand and optimize the processes, since existing models often lack process configurations and details. Earlier model software didn’t allow for flexible model modification which created a need for too many compromises, but now tailor-made models are possible,” Eppu Väänänen explains.

The dynamic process model created by Eppu and his team will be used both in the detailed planning and during process operation of the Metsä-Sairila WWTP where it will allow savings in energy and chemical consumption due to membrane cleaning.