Identification of natural organic matter (NOM) transport behavior near the membrane surface using flow field-flow-fractionation (fl-FFF) micro channel

摘要

Membrane fouling due to natural organic matter (NOM) is a major obstacle in the membrane filtration process for water treatment and water reuse facilities. Flow field-flow-fractionation (fl-FFF) is capable to evaluate interactions between NOM and the membrane surface in terms of size exclusion, electrostatic interaction and reversible/irreversible adsorption, as well as NOM characterisations. The effects of the membrane surface charge and ionic strength on the behavior of polystyrene sulfonates (PSS) and NOM in membranes were demonstrated using fl-FFF. Membrane fouling due to NOM adsorption on the membrane surface was investigated by, and correlated to, fl-FFF. Ionic strength had an effect on both the structure of PSS or NOM and the membrane matrix so that different retention peaks were observed. It also affected the interaction between membrane and solute, and resulted in solute aggregation and adsorption on the membrane surface. Through static and dynamic adsorption tests, the adsorption of the solute was tried to correlate with fl-FFF. As various membranes were used for the accumulation wall of the fl-FFF tested, this could simulate solute behavior in membrane filtration under similar chemical and hydrodynamic operating conditions. Thus, the fl-FFF system can be used to simulate actual membrane filtration with various solutes such as NOM in order to predict membrane performance for solutes (an earlier elution time for a certain solute with a membrane implies less fouling propensity and greater removal capability for the system).