Effects of pre-ozonation on the ultrafiltration of different natural organic matter (NOM) fractions: Membrane fouling mitigation, prediction and mechanism

Ultraviolet/persulfate (UV/PS) pretreatment of typical natural organic matter (NOM): Variation of characteristics and control of membrane fouling

Control of natural organic matter fouling of ultrafiltration membrane by adsorption pretreatment: Comparison of mesoporous adsorbent resin and powdered activated carbon

Application of UV/chlorine pretreatment for controlling ultrafiltration (UF) membrane fouling caused by different natural organic fractions

Effect of UV/ClO2 pretreatment on controlling ultrafiltration membrane fouling of different natural organic matter (NOM) fractions

Novel insights into the interaction reactive components and synergistic fouling mechanisms of ultrafiltration by natural organic matter fractions and kaolin

Improving ultrafiltration membrane performance with pre-deposited carbon nanotubes/nanofibers layers for drinking water treatment

Effect of peroxymonosulfate oxidation activated by powdered activated carbon for mitigating ultrafiltration membrane fouling caused by different natural organic matter fractions

This paper focused on the effects of powdered activated carbon (PAC) dosage on ultrafiltration (UF) membrane flux caused by natural organic matter (NOM). Three model foulants, humic acid (HA), bovine serum albumin (BSA) and sodium alginate (SA), were adopted to represent different NOM fractions in secondary effluent treated by the combined process of PAC-UF. Moreover, the membrane fouling resistance and fouling mechanism were also analyzed. The results indicated that the best PAC dosage for the membrane flux variation was 20 mg/L for HA and SA, and 10 mg/L for BSA. SA caused the most serious membrane fouling, which was mainly reversible fouling. The membrane fouling caused by HA and BSA was mainly irreversible membrane fouling. The membrane fouling caused by organics happened mainly at the initial stage of filtration. Because the filter cake layer formed by a moderate amount of PAC could intercept organics, the membrane fouling, especially the irreversible fouling, could be reduced.

The presence of natural organic matter (NOM) in groundwater could play an important role on removal of contaminants by nano-zero valent iron (NZVI). NOM has heterogeneous structure and could be divided into 6 fractions based on polarity and charges including hydrophobic acid (HPOA), hydrophobic base (HPOB), hydrophobic neutral (HPON), hydrophilic acid (HPIA), hydrophilic base (HPIB), and hydrophilic neutral (HPIN). This study investigated the interaction between NOM fractions and NZVI using NOM surrogates. The reactivity between NZVI and NOM fractions isolated and bulk NOM from two sources including groundwater (GWNOM), Khon Kaen, Thailand and Suwannee River NOM (SRNOM), USA was also examined. The results showed that for NOM surrogates, humic acid (HPOA) had the highest interaction with NZVI while other NOM surrogates ((L-tryptophan, HPON), (aniline, HPOB), (oxalic acid, HPIA), (L-asparagine, HPIB), (D-xylose, HPIN)) had limited interactions. The Freundlich adsorption isotherm was found to fit the adsorption of HPOA and HPIA surrogates on NZVI. The results of fractionated NOM under various pH (5, 7, and 9) revealed that NOM fractions had more interaction with NZVI at pH 5 for both GWNOM and SRNOM. HPOA of GWNOM had the highest adsorption capacity (qe) of 6.95 mg/g while HPIN yielded the lowest qe (1.42 mg/g) at pH 5. For SRNOM, HPIA has the highest qe of 18.66 mg/g at pH 5 whereas the lowest qe of 1.45 mg/g was obtained from HPIN at pH 7. In addition, the effect of competitive interaction of NOM fractions was studied. HPOA was found to compete with HPON for GWNOM while HPOA remained the main fraction which reacted with NZVI for SRNOM. The findings of this study suggest that different components of NOM had different interactions with NZVI. Acid fractions tend to have more interaction than the other fractions. To apply NZVI for groundwater remediation, the composition of NOM should be considered to project the performance of NZVI for contaminant removals.

Pyrogenic humic acid (HA) is released into the environment during the large-scale application of biochar. However, the biogeochemistry of pyrogenic organic matter (PyOM) fractions and their sorption of hydrophobic organic compounds (HOCs) are poorly understood in comparison with natural organic matter (NOM) fractions. HA and humin (HM) fractions isolated from soils and the oxidized biochars were characterized. Sorption of phenanthrene (PHE) by these fractions was also examined. The characterization results demonstrate that pyrogenic HAs are different from natural HAs, with the former having lower atomic H/C ratios, more abundant aromatic C, and higher concentrations of surface carboxylic groups. Compared with the fresh biochars, the Koc of PHE on their oxidized biochars, pyrogenic HA, and HM fractions were undiminished, which is encouraging for the use of biochar in soil remediation. The PyOM fractions exhibited stronger nonlinear sorption than the NOM fractions. In addition, the PyOM fractions had higher sorption capacity than the NOM fractions due to their low polar C content and high aryl C content. The results obtained from this work will shed new light on the impact of the addition of biochar on the biogeochemistry of soil organic matter and on the fate of HOCs in biochar-amended soil.

The fouling mechanism of the anion exchange membrane (AEM) induced by natural organic matter (NOM) in the absence and presence of calcium ions was systematically investigated via the extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) approach. Sodium alginate (SA), humic acid (HA), and bovine serum albumin (BSA) were utilized as model NOM fractions. The results indicated that the presence of calcium ions tremendously aggravated the NOM fouling on the anion exchange membrane because of Ca-NOM complex formation. Furthermore, analysis of the interaction energy between the membrane surface and foulants via xDLVO revealed that short-range acid–base (AB) interaction energy played a significant role in the compositions of interaction energy during the electrodialysis (ED) process. The influence of NOM fractions in the presence of calcium ions on membrane fouling followed the order: SA > BSA > HA. This study demonstrated that the interaction energy was a dominating indicator for evaluating the tendency of anion exchange membranes fouling by natural organic matter.

Enhanced microbial reduction of Cr(VI) and U(VI) by different natural organic matter fractions

Role of natural organic matter (NOM), colloidal particles, and solution chemistry on ultrafiltration performance

Natural organic matter (NOM) fouling of ultrafiltration membranes: fractionation of NOM in surface water and characterisation by LC-OCD

Effects of concentration and chemical composition of natural organic matter on the aggregative behavior of silver nanoparticles