Effects of humic substance characteristics on UF performance

Abstract

AbstractÐThe role of humic substances in general and hydrophobicity of humic substances in particular on membrane permeate¯ux is unclear. The main goal of the present study is to evaluate the eect of fractionated humic substances on ultra®ltration (UF) performance. A commercial humic solution was subjected to a hydrophobic resin for fractionation of the hydrophobic and hydrophilic fraction. These fractions were further fractionated into dierent molecular wight groups, using gel ®ltration chromatography. The hydrophobic fraction accounts for 85% organic carbon recovered and has a signi®cantly high THM (trihalomethane) formation potential, or 190 mg/mg C. The hydrophilic fraction exhibits the worst¯ux decline despite little solute rejection. The results of molecular weight fractionation of both hydrophobic and hydrophilic fractions further indicate that those molecules with the largest molecular weight (6.5±22.6 kDa) exhibit the worst¯ux decline. The UF system evaluated is unable to remove a signi®cant portion of THM precursors, resulting in potentially high THMs in the permeate. The use of powdered activated carbon (PAC) for the pretreatment of hydrophobic/ hydrophilic humic substances or in an integrated PAC-UF system exhibits an enhanced membrane fouling. #

Flux and performance improvement in a submerged anaerobic membrane bioreactor (SAMBR) using powdered activated carbon (PAC)

“…The addition of 1.67 g l -1 PAC significantly reduced the high MW organics in the reactor, however, the further addition of another 1.67 g l -1 PAC did not reduce the amount of remaining high MW compounds any further. This might be because the remaining non-adsorptive substances have a low affinity for PAC, or that the carbon surface has been modified due to the adsorption of organics [20,21].…”

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

“…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].…”

Effect of polyferric chloride (PFC) doses and pH on the fractal characteristics of PFC–HA flocs

“…Generally, elimination of these humic substances during drinking water treatment is carried out by coagulation with hydrolyzed metal species such as aluminum and iron salts. However, the presence of uncoagulated humic materials in clarified water is responsible for reduced adsorption capacity in activated carbon beds, taste and odor of the finished water, membrane fouling, trihalomethane formation during chlorine disinfection, or biological regrowth in the distribution network [1][2][3]. Accord-ingly, considerable attention has been focused on the technologies and their own efficiency for eliminating these substances.…”

“…The United States Environmental Protection Agency has proposed that enhanced coagulation technology (ECT) is the best available technology (BAT) for the removal of these compounds [4][5][6]. Previous studies have paid close attention to the reaction behavior between FeCl 3 and humic acids [4][5][6], and it has been shown that FeCl 3 performs well in the removal of HA during enhanced coagulation processes. Recently, several studies have focused on the removal of HA and coagulated flocs with polyferric chloride (PFC), an inorganic polymer flocculant (IPF) that performs well in particle removal from natural water or wastewater.…”