Fouling layer formation in ultrafiltration membrane by flocs formed in electrocoagulation
The research is supported by a doctoral grant from the Friedrich Ebert Foundation.
Funding Period: 01.10.2021 – 30.09.2022
In water treatment, filtration is an essential process to remove fine particles. Membrane filtration is recently often applied in water works due to its capability of removing a wide range of water pollutants including drinking water pathogens, i. e. viruses, bacteria and parasites. However, over membrane filtration time, the initial build-up of a highly concentrated fouled cake layer on the membrane surface results in a decline of the pure water flux.
In order to control fouling formation, and consequently, reduce the backwashing frequency and its drawbacks, a better mechanistic comprehension of flocs movement inside the membrane contributes to suggest the optimal fouling prevention and membrane cleaning strategy. This creates the necessity to carry out numerical simulations to model floc transport and fouling layer formation elucidate a major advance, providing insights not possible through experiments. Recently, CFD is used in membrane related applications to optimize its performance and will be used to couple flocs transport inside ultrafiltration (UF) capillary membranes to account for the transport of flocs and derive the fouling layer height and its influence on the flow field. The temporal changes in floc dimensions and average size, i. e. flocs structural evolution during initial stages of an aggregation process reflects an influence on the collision frequency and also, later on, the floc settling velocity and floc deposition on the membrane surface.
Chemical coagulation is often applied in water and wastewater treatment plants in order to facilitate the destabilization of pollutants and form bigger flocs which can be separated in the subsequent separation processes. However, an alternative technology was in the last three decades represented, namely, electrocoagulation (EC) which can form flocs as good as CC (mostly with a better removal efficiency, as will be discussed next) and also considered to be a CO2-free, possible-green process with no added chemicals. EC can also be applied as a pre-treatment before membrane filtration in water purification.