Efficacy of hybrid adsorption/membrane pretreatment for low pressure membrane

Abstract

Fouling by natural organic matter (NOM) is a major obstacle when water from natural sources is treated using low-pressure membranes. Prior research by our group has demonstrated that passing natural water through a thin, pre-deposited layer of heated aluminum oxide particles (HAOPs) can remove substantial amounts of NOM from the feed and thereby reduce the fouling rate of downstream membranes. The work reported here explored the technical efficacy of such a pretreatment process under more challenging (and therefore realistic) conditions than reported earlier. Several analytical techniques were applied to the feed and permeate in an attempt to identify the key fouling components. The results demonstrate that a HAOPs layer can be pre-deposited on a stainless steel mesh and then be readily washed off at the end of a filtration cycle with very little irreversible fouling due to residual NOM or HAOPs left on the mesh. In addition, the pretreatment step removes enough foulant to allow a downstream UF membrane to operate at significantly higher fluxes than when conventional pretreatment is applied. HAOPs pretreatment also reduced the formation of chlorinated and brominated trihalomethanes (THM4) by more than 67% and of haloacetic acids (HAA9) by 64%-88% in simulated distribution system (SDS) tests.

Investigations of the mechanism of the fouling in microgranular adsorptive filtration

“…Presented results confirm existing reports that passage of feed through a thin layer of pre-coated HAOPs removes NOM and membrane foulants and substantially removes the majority of the UV254 from the raw water KIM et al 2007;2010;LIU 2016;MALCZEWSKA 2016;MALCZEWSKA, BENJAMIN 2016;MALCZEWSKA et al 2015].…”

Effects of a Novel Adsorbent on Membrane Fouling by Natural Organic Matter in Drinking Water Treatment

“…Early research on HAOPs documented reductions in membrane fouling and THM formation potential by pre-deposited HAOPs [10]. Subsequent work showed that, if raw water is filtered through a thin, pre-deposited layer of HAOPs upstream of a membrane, substantial amounts of NOM can be removed from the water, thereby reducing the fouling rate of downstream membrane units [11,12,13,14,15,16].…”

The use of ultrasound to mitigate membrane fouling in desalination and water treatment

“…Often pretreatment methods are used as preventative measures for controlling membrane fouling. These include the use of prefilters, screens, precipitation, coagulation, flocculation, or chemicals to reduce the amount of foulants in the feed [30][31][32][33]. In addition, membrane surface modification may be performed to lower the affinity of foulants for the membrane surface [30,[34][35][36][37][38][39].…”