Understanding the Size and Character of Fouling-Causing Substances from Effluent Organic Matter (EfOM) in Low-Pressure Membrane Filtration

Abstract

Stirred cell tests with microfiltration (MF) and ultrafiltration (UF) membranes show high flux decline for WWTP effluents. For the MF membrane, for example, the flux declines within 15 min to 70-80% of the initial flux (J0 is in the range of 1000 L/m2h to 1500 L/m2h). This time corresponds to the filtration of a cumulative volume of 110 L/m2. Feed and permeate samples of the stirred cell tests are analyzed by size-exclusion chromatography (SEC) with on-line organic carbon and UVA254 detection. The resulting chromatograms exhibit a clear difference between the feed and permeate samples in the so-called polysaccharide (PS) peak. The substances eluting in the PS peak (organic colloids, polysaccharides, and proteins) are retained completely by UF membranes and partly by MF membranes, and are responsible for the observed fouling. By sequential filtration experiments the sizes of these macromolecules are determined to be in the range of 10 to 100 nm.

Investigation of pre-coagulation and powder activate carbon adsorption on ultrafiltration membrane fouling

“…Residual turbidity measurements (Hach2100, USA) were made for samples in the two membrane tanks. The concentration of NH 4 þ -N was determined by the colorimetric method using a spectrometer by APHA Standard Methods [45].…”

“…However, natural organic matter (NOM) is often a major foulant during the ultrafiltration of surface water [1,2], since it contains a complex mixture of humic and fulvic acids, proteins, carbohydrates of various molecular sizes and functional groups [2][3][4][5], which can either bind to the membrane surface or support the development of microbiological fouling.…”

“…However, not all contaminants can be fully removed by the coagulation process, particularly biopolymers, such as polysaccharides and proteins [3][4][5]. In view of this, the combination of powder activate carbon (PAC) adsorption and UF has been reported to be more effective in the removal of organic contaminants, either as represented by total organic carbon or any other special pollutants [11][12][13][14][15][16].…”

Retention of Silica Nanoparticles in a Lab-Scale Membrane Bioreactor: Implications for Process Performance and Membrane Fouling

“…Colloidal fouling is a phenomenon typical [31,34,35] but not exclusive to microfiltration processes [13,36,37]. It is influenced by some factors including colloidal particle size, applied pressure and the interaction with other colloidal particles that may be present in activated sludge [11,38,39].…”

Membrane Fouling Potential of Secondary Effluent Organic Matter (EfOM) from Conventional Activated Sludge Process

“…Generally, biologically treated secondary effluent consists of fine particulate suspended solids, organic/inorganic colloids and solutes [1]. Among them, the organic colloids and solutes, defined as effluent organic matter (EfOM), can be considered as the main foulants especially for UF, NF and RO [2]. Therefore, an investigation on the fouling potential of EfOM is necessary to develop effective solutions to control membrane fouling.…”