Effect of NOM characteristics and membrane type on microfiltration performance

Abstract

Efforts to understand and predict the role of different organic fractions in the fouling of low-pressure membranes are presented. Preliminary experiments with an experimental apparatus that incorporates automatic backwashing and filtration over several days has shown that microfiltration of the hydrophilic fractions leads to rapid flux decline and the formation of a cake or gel layer, while the hydrophobic fractions show a steady flux decline and no obvious formation of a gel or cake layer. The addition of calcium to the weakly hydrophobic acid (WHA) fraction led to the formation of a gel layer from associations between components of the WHA. The dominant foulants were found to be the neutral and charged hydrophilic compounds, with hydrophobic and small pore size membranes being the most readily fouled. The findings suggest that surface analyses such as FTIR will preferentially identify hydrophilic compounds as the main foulants, as these components form a gel layer on the surface while the hydrophobic compounds adsorb within the membrane pores.Furthermore, coagulation pre-treatment is also likely to reduce fouling by reducing pore constriction rather than the formation of a gel layer, as coagulants remove the hydrophobic compounds to a large extent and very little of the hydrophilic neutral components.

Estabilidade de fracoes de substancias humicas de turfa obtidas em um equipamento comercial de ultrafiltracao

“…O comprimento de onda que tem sido mais utilizado é o de 254 nm. (BERTHE;REDONB;FEUILLADE, 2008;GRAYA et al, 2007). Dessa forma, utilizou-se esse comprimento de onda como parâmetro para verifi car a estabilidade das frações de SH.…”

Chlorine for Water Disinfection: Properties, Applications and Health Effects

“…A pretreatment of water using coagulation process is proposed to reduce the level of pore constriction by hydrophobic compounds. The coagulation process is known to preferentially remove the hydrophobic and charged compounds (Gray et al 2007). …”

Effect of Membrane Type for the Treatment of Organized Industrial Zone (OIZ) Wastewater with a Membrane Bioreactor (MBR): Batch Experiments

“…While MBR batch studies [15,16] were conducted for the removal of some micropollutants, membrane types were investigated in other studies [17,18]. One study on natural organic matter (NOM) removal investigated using hollowfiber (HF) membranes-two hydrophobic and one hydrophilic.…”

“…One study on natural organic matter (NOM) removal investigated using hollowfiber (HF) membranes-two hydrophobic and one hydrophilic. Hydrophobic ones fouled more quickly because hydrophilic compounds formed a gel layer on the surface of the membrane [17]. Another study on membrane type and materials was conducted using three different MF membranes with the same pore sizes.…”