Project ID: 2003HI26B

Title: Prevention of Colloidal Fouling in Crossflow Membrane Filtration: Searching for Optimal Operation Conditions

Project Type: Research

Focus Categories: Treatment, Solute Transport, Models

Keywords: membrane filtration, colloidal fouling, permeate flux decline

Start Date: 03/01/2003

End Date: 02/29/2004

Federal Funds: $23235.00

Matching Funds: $46562.00

Congressional District: Hawaii 1st

Principal Investigators: Kim, Albert Sechurl (University of Hawaii at Manoa); Liu, Clark (University of Hawaii)

Abstract: Crossflow membrane filtration processes involving reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF) have steadily gained importance in environmental engineering separations over the past decade. Numerous improvements in the technology have spurred widespread adaptation of this process in environmental, chemical, pharmaceutical,
and biomedical applications. Microfiltration is used in a wide variety of industrial applications where the particulate materials of a size greater than 0.1 mm, have to be retained form a liquid so the applications are the sterilization and clarification of all kinds of beverages and pharmaceuticals, and in particular the pre-treatment of other membrane filtrations, especially in water and wastewater treatment. Ultrafiltration and nanofiltration, in particular, are important processes for the removal of solutes, macromolecules (such as natural organic matter), pathogenic viruses, and small colloidal materials in water and wastewater treatment. Water desalination by reverse osmosis to produce potable water from seawater or brackish water by engineered processes has become increasingly important to provide alternative water supplies, especially in Hawaii and other Pacific and Asian island areas. There are, however, several aspects of this constantly evolving technology that have not yet been addressed
conclusively and still pose a formidable obstacle toward its wide acceptance. One of these importance aspects in the pressure-driven membrane process is membrane fouling due to the concentration polarization and cake formation of particulate materials.

The objectives of the proposed research for fouling prevention are (1) to develop a fundamental statistical mechanical approach to identify the transition point from a liquid-like to a solid-like structure of colloidal dispersions due to several physico-chemical and operational conditions in membrane filtration, (2) to make a simulation-based empirical correlation that can be used by engineers for determining optimum operation conditions in pilot and/or real membrane systems, and (3) to decide the critical permeate flux under which only concentration polarization is a dominant cause of the flux decline before the cake layer forms.
Therefore, the proposed research will provide answers to the following important questions:

(i) how do the inter-particle interactions and dispersion microstructure govern the nature and extent of concentration polarization, the transition to cake formation, and the resulting permeate flux decline behavior?, (ii) What is the particle concentration at which a colloidal dispersion undergoes a transition from a liquid-like disordered state (pure concentration polarization) to a solid-like state (cake/gel layer) during membrane filtration processes?, and (iii) How can the membrane fouling by the cake formation be prevented and/or reduced by changing physico-chemical and operating conditions of the membrane filtration with a given particle suspension? Based on the results to be provided, this research will enhance our understanding of fouling problem, and thus will help developing solutions to prevent and treat membrane fouling.

Progress/Completion Report PDF