Microfiltration

Abstract

Microfiltration (MF) and ultrafiltration are popular in drinking water and wastewater treatment because integral membranes are absolute barriers for difficult‐to‐inactivate pathogenic protozoa, and the turbidity of membrane‐filtered water is well below current and anticipated regulations. The focus of this section is to provide a broad overview of MF from an environmental engineering viewpoint, including its capabilities and limitations, as it pertains to water and wastewater treatment, configuration and field testing of commercially available systems before full‐scale implementation, and mechanisms and control of fouling. Other industrial applications of microfiltration are also briefly discussed. Constant pressure and constant flux blocking laws to predict fouling mechanisms during dead‐end MF are briefly summarized. The use of chemical coagulation and electrochemical pretreatment to improve MF performance in terms of both fouling and filtered water quality (with respect to natural organic matter, disinfection by‐product precursors, and viruses) is also discussed.

Optimal backwashing in dead-end bacterial microfiltration with irreversible attachment mediated by extracellular polymeric substances production

“…Dead-end microfiltration (MF) and ultrafiltration (UF) are used in a variety of industrial and municipal settings as efficient and practical methods for removing turbidity, microorganisms, and other colloidal pollutants (1)(2)(3). During bacterial filtration, accumulation of microorganisms on the MF/UF membrane surface or within its porous matrix causes fouling (4,5).…”

“…In practice, the timing and duration of the backwashing cycles is determined empirically -often using proprietary scheduling algorithms developed by the manufacturer. Input is also provided by consulting engineers when on-site pilot-scale testing is performed in support of plant design or to comply with regulations (1).…”