Hydrophilic Matter Research Articles

Composition and spectroscopic characteristics of dissolved organic matter extracted from the sediment of Erhai Lake in China

Purpose The content and composition of dissolved organic matter (DOM) in sediment directly affect nutrient cycling and material exchange in lake ecosystems. This study investigated the content and composition of DOM and its fractions in sediments, as well as the relationship between the different parameters and nitrogen (N) forms in DOM. The main aim of this study was to evaluate the compositional characteristics of DOM, hydrophobic bases (HOB), hydrophobic acids (HOA), hydrophobic neutral fractions (HON), and hydrophilic matter (HIM) in sediments from Erhai Lake, China.

Reuse of PAC and alum sludge (RPAS) process: pretreatment to reduce membrane fouling

In this study, a novel reuse of powdered activated carbon (PAC) and alum sludge (RPAS) process to reduce membrane fouling for drinking water treatment was evaluated by laboratory-scale experiments. As compared to coagulation, PAC combined with coagulation and reuse of alum sludge processes, RPAS process performed better in controlling trans-membrane pressure increase and reducing membrane resistances in both short-term and long-term periodical filtration. Removals of turbidity, DOC, UV254, BDOC and THMFP were 93.8, 37.3, 41.1, 83.0 and 57.9% on average by RPAS pretreatment, respectively. The results of fractionation of organic matters indicated that hydrophobic acids and hydrophilic matters were efficiently removed, while organic matters with the molecular weight (MW) more than 3 k Da was well removed with a removal efficiency of 50.4%, and that of MW less than 1 k Da were reduced by 32.6% by RPAS pretreatment, which could be attributed to the integration of PAC adsorption and the enhanced coagulation of alum sludge.

Disinfection byproduct precursor removal by enhanced coagulation and their distribution in chemical fractions

Raw water from the Songhua River was treated by four types of coagulants, ferric chloride (FeCl3), aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PACl) and composite polyaluminum (HPAC), in order to remove dissolved organic matter (DOM). Considering the disinfection byproduct (DBP) precursor treatability, DOM was divided into five chemical fractions based on resin adsorption. Trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP) were measured for each fraction. The results showed that hydrophobic acids (HoA), hydrophilic matter (HiM) and hydrophobic neutral (HoN) were the dominant fractions. Although both HoN and HoA were the main THM precursors, the contribution for THMFP changed after coagulation. Additionally, HoA and HiM were the main HAA precursors, while the contribution of HoN to HAAFP significantly increased after coagulation. HoM was more easily removed than HiM, no matter which coagulant was used, especially under enhanced coagulation conditions. DOC removal was highest for enhanced coagulation using FeCl3 while DBPFP was lowest using PACl. This could indicate that not all DOC fractions contained the precursors of DBPs. Reduction of THMFP and HAAFP by PACl under enhanced coagulation could reach 51% and 59% respectively.

Advanced oxidation of bromide-containing drinking water: A balance between bromate and trihalomethane formation control

Addition of H2O2 has been employed to repress bromate formation during ozonation of bromide-containing source water. However, the addition of H2O2 will change the oxidation pathways of organic compounds due to the generation of abundant hydroxyl radicals, which could affect the removal efficacy of trihalomethane precursors via the combination of ozone and biological activated carbon (O3-BAC). In this study, we evaluated the effects of H2O2 addition on bromate formation and trihalomethane formation potential (THMFP) reduction during treatment of bromide-containing (97.6–129.1 μg/L) source water by the O3-BAC process. At an ozone dose of 4.2 mg/L, an H2O2/O3 (g/g) ratio of over 1.0 was required to maintain the bromate concentration below 10.0 μg/L, while a much lower H2O2/O3 ratio was sufficient for a lower ozone dose. An H2O2/O3 (g/g) ratio below 0.3 should be avoided since the bromate concentration will increase with increasing H2O2 dose below this ratio. However, the addition of H2O2 at an ozone dose of 3.2 mg/L and an H2O2/O3 ratio of 1.0 resulted in a 43% decrease in THMFP removal when compared with the O3-BAC process. The optimum H2O2/O3 (g/g) ratio for balancing bromate and trihalomethane control was about 0.7–1.0. Fractionation of organic materials showed that the addition of H2O2 decreased the removal efficacy of the hydrophilic matter fraction of DOC by ozonation and increased the reactivity of the hydrophobic fractions during formation of trihalomethane, which may be the two main reasons responsible for the decrease in THMFP reduction efficacy. Overall, this study clearly demonstrated that it is necessary to balance bromate reduction and THMFP control when adopting an H2O2 addition strategy.

Removal and transformation characterization of refractory components from biologically treated landfill leachate by Fe2+/NaClO and Fenton oxidation

Treatment of effluent from biological unit for landfill leachate by NaClO enhanced Fe2+ coagulation (Fe2+/NaClO) followed by Fenton oxidation was studied. Firstly, removal of COD, NH4+, and color degree by individual coagulation, NaClO oxidation and Fe2+/NaClO process was compared under the condition of 10mmolL−1 FeSO4 and 12.5mmolL−1 NaClO. COD removal in the Fe2+/NaClO process was 53.5%, which was higher than 23.5% and 12.5% in the individual Fe2+ coagulation or NaClO oxidation, respectively. And, NH4+ removal was nearly same in the Fe2+/NaClO and individual NaClO oxidation process. Furthermore, the removal efficiency of COD was increased to be 86.0% via Fenton oxidation with a 40mmolL−1 Fe2+. Based on the fraction results via ultrafiltration membranes, it was observed that the fractions with molecular weight ranging from 100 to 30kDa were efficiently removed via the coagulation process. The fractions with molecular weight less than 10kDa were mainly removed via the Fenton oxidation. Based on the resin fractionation results, the fractions of the hydrophilic matter and hydrophobic acids dominated in the effluents from biological unit. The fractions of hydrophobic neutrals and hydrophobic bases were largely removed via the Fenton oxidation process.

A detailed organic matter characterization of pretreated seawater using low pressure microfiltration hybrid systems

In this study, two different submerged membrane hybrid systems (SMHSs) namely (i) submerged membrane coagulation hybrid system (SMCHS) and (ii) submerged membrane coagulation-adsorption hybrid system (SMCAHS) were investigated as pretreatment options for seawater reverse osmosis. Organic matters in seawater before and after pretreatment were characterized in terms of XAD fractionation, molecular weight distribution (MWD) and fluorescence. A detailed study on the seawater organic matter (SWOM) structure was made through 1H-nuclear magnetic resonance (1H NMR), pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS) and liquid chromatography–mass spectrometry-ion trap-time of fright (LC/MS-IT-TOF). The seawater investigated in this study is mainly composed of hydrophilic matter (57±3.2%). SMHSs removed a significant amount of organic matter. The EEM fluorescence showed a removal of humic-like materials by SMHSs. In addition, humic-like materials relative to protein-like compounds were reduced significantly but the aromaticity of humic-like materials increased. After pretreatment by SMHSs, humics and biopolymers of over 900Da. were found to be reduced and their structure associated with element composition was also changed. The transformation of the SWOM structure after SMHSs pretreatment may have been due to hydrolyzation or oxidization of the organic compounds such as humics and biopolymers resulting in poly-conjugation to aromatic compounds. SMHSs were effective in improving the RO performance leading to higher RO permeate flux and lower permeate flux decline. The pretreatment reduced the amount of foulants on the RO membrane.

Directional Liquid Spreading over Chemically Defined Radial Wettability Gradients

We investigate the motion of liquid droplets on chemically defined radial wettability gradients. The patterns consist of hydrophobic fluorinated self-assembled monolayers (SAMs) on oxidized silicon substrates. The design comprises a central hydrophobic circle of unpatterned SAMs surrounded by annular regions of radially oriented stripes of alternating wettability, i.e., hydrophilic and hydrophobic. Variation in the relative width of the stripes allows control over the macroscopic wettability. When a droplet is deposited in the middle, it will start to move over to the radially defined wettability gradient, away from the center because of the increasing relative surface area of hydrophilic matter for larger radii in the pattern. The focus of this article is on a qualitative description of the characteristic motion on such types of anisotropic patterns. The influence of design parameters such as pattern dimensions, steepness of the gradient, and connection between different areas on the behavior of the liquid are analyzed and discussed in terms of advancing and receding contact lines, contact angles, spatial extent, and overall velocity of the motion.

A comparison of organic matters responsible for immersed ultrafiltration membranes fouling in drinking water treatment

ABSTRACTMembrane fouling caused by natural organic matter is an important problem in drinking water treatment. In this study, bench‐scale experiments using three different types of ultrafiltration (UF) membranes were carried out with the surface water of the Songhua River in China in order to investigate the effect of natural organic matter on membrane fouling. Organic matter that caused reversible and irreversible fouling in the filtration operation was desorbed from the fouled membranes and subjected to chemical fractionation and Fourier transform infrared analyses. These analyses revealed that hydrophilic organic matter accounted for the majority of both reversible and irreversible fouling, regardless of the type of membrane. Results also demonstrated that the type of organic matter responsible for fouling differed significantly and depended on the type of membrane. The main types of organic matter that caused reversible fouling were hydrophilic organic matter and hydrophobic acids, for the polyvinyl chloride (PVC) and polysulfone (PS) membranes and hydrophilic matter and weakly hydrophobic acids, for the polyvinylidene fluoride (PVDF) membrane. Hydrophobic acids were largely responsible for the irreversible fouling of PVDF membranes. The PVC membrane was more vulnerable to fouling because of the hydrophilic fraction, and the PS membrane was most easily fouled by the hydrophobic neutral fraction. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

Interaction of phenanthrene with dissolved organic matter and its fractions from leachate of different landfill ages

Dissolved organic matter (DOM) in leachate from landfills of three different ages (0, 5, and 10 year) was partitioned into hydrophobic acid, hydrophobic neutral, and hydrophilic matter fractions using the fractionation method employing XAD-8 resin. The spectroscopic characteristics of these fractions were determined through constant-wavelength synchronous fluorescence spectrometry (CWSFS). The interaction characteristic of phenanthrene with these fractions was determined through the fluorescence quenching method and CWSFS. The results revealed that the composition of DOM became complex with the increase in landfill age. The partition coefficients (K doc) for the three DOM samples of different landfill ages are in the order 10 a DOM > 5 a DOM > 0 a DOM. The hydrophobic fraction showed the highest K doc value among the DOM fractions. Lower linearity Stern–Volmer plots were observed in 10 a DOM and its hydrophobic fractions. CWSFS spectra showed that a special site was fully occupied with the addition of the quencher. Desorption was found in some fractions. Therefore, CWSFS is a sensitive tool for the detection of DOM-polycyclic aromatic hydrocarbon interaction.

Changes in different organic matter fractions during conventional treatment and advanced treatment

XAD-8 resin isolation of organic matter in water was used to divide organic matter into the hydrophobic and hydrophilic fractions. A pilot plant was used to investigate the change in both fractions during conventional and advanced treatment processes. The treatment of hydrophobic organics (HPO), rather than hydrophilic organicas (HPI), should carry greater emphasis due to HPO's higher trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP). The removal of hydrophobic matter and its transmission into hydrophilic matter reduced ultimate DBP yield during the disinfection process. The results showed that sand filtration, ozonation, and biological activated carbon (BAC) filtration had distinct influences on the removal of both organic fractions. Additionally, the combination of processes changed the organic fraction proportions present during treatment. The use of ozonation and BAC maximized organic matter removal efficiency, especially for the hydrophobic fraction. In sum, the combination of pre-ozonation, conventional treatment, and O 3-BAC removed 48% of dissolved organic carbon (DOC), 60% of HPO, 30% of HPI, 63% of THMFP, and 85% of HAAFP. The use of conventional treatment and O 3-BAC without pre-ozonation had a comparable performance, removing 51% of DOC, 56% of HPO, 45% of HPI, 61% of THMFP, and 72% of HAAFP. The effectiveness of this analysis method indicated that resin isolation and fractionation should be standardized as an applicable test to help assess water treatment process efficiency.

Fluorescence excitation–emission matrix spectroscopy with regional integration analysis for characterizing composition and transformation of dissolved organic matter in landfill leachates

Dissolved organic matter (DOM) obtained from landfill leachates was separated into hydrophobic base, hydrophilic matter (HIM), hydrophobic acid (HOA), and hydrophobic neutral fractions. The composition and transformation of the DOM and its fractions were investigated. The results show that the DOM isolated from young, intermediate, and old landfill leachates were mainly composed of tyrosine-, tryptophan-, and humic- and fulvic-like substances, respectively. The primary fractions of the DOM in leachates were HOA and HIM. The HOA and HIM fractions from young leachates predominantly contained tryptophan- and tyrosine-like materials, respectively. The HOA fractions in intermediate and old leachates were mainly composed of humic- and fulvic-like materials, whereas the HIM fractions were dominated by tryptophan-like materials and humic- and fulvic-like substances. The hydrophobic organic fractions and humic- and fulvic-like substances increased with time, whereas the HIM and the tyrosine-like materials decreased during the landfill process, rendering biological processing of leachates ineffective.

Effect of polar-dissolved organic matter fractions on the mobility of prometryne in soil

Purpose Using two fractions of dissolved organic matter (DOM) with different polarity, we carried out the experiments with standard batch equilibration, soil column leaching, and soil thin layer chromatography to investigate the behavior of the herbicide prometryne in soils. The purpose of the study was to: (1) separate DOM into hydrophilic matter and hydrophobic acid forms and characterize their chemical properties; (2) analyze interaction between the DOM fractions and prometryne in soils.

Effects of rice straw–derived dissolved organic matter on pyrene sorption by soil

The objectives of the present study were to elucidate the chemical and structural properties of dissolved organic matter (DOM) derived from aerobic decay of rice straw and to quantify the effect of the DOM on the sorption of pyrene on soil. The DOM samples were obtained from microcosms incubated at 0, 21, 63, and 180 d. The bulk DOM samples were fractionated to four fractions: hydrophilic matter (HIM), acid-insoluble matter (AIM), hydrophobic acid (HOA), and hydrophobic neutral (HON) fractions. The bulk DOM and the four DOM fractions were characterized for their elemental compositions and functionalities. The results showed that HIM had the highest H/C atomic ratios, whereas HOA and AIM had the lowest H/C atomic ratios. These DOM samples were used as the background DOMs in the initial aqueous solutions for measuring sorption of pyrene on a paddy soil. The results indicated that, among the four DOM fractions, HOA, HON, and AIM significantly lowered the pyrene sorption coefficients, but HIM had little or no effect on the pyrene sorption by the soil. It appears that less polar AIM and HON had stronger binding affinities for pyrene in water, reducing the sorption coefficient for the soil, whereas more polar and less aromatic HIM had much weaker binding affinity for pyrene in water, causing little or no effect on the pyrene sorption by the soil. The present study showed that rice straw-derived DOM may enhance desorption and transport of organic pollutants in soil-water systems.

Membrane adsorption bioreactor (MABR) for treating slightly polluted surface water supplies: As compared to membrane bioreactor (MBR)

In this paper, a submerged membrane adsorption bioreactor (MABR) was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5 h. As powdered activated carbon (PAC) was added to the bioreactor at 8 mg/L raw water, the MABR achieved much higher removal efficiency for organic matter in the raw water than the parallel-operated membrane bioreactor (MBR). Moreover, the trans-membrane pressure (TMP) of MABR developed much lower than that of MBR, demonstrating PAC in MABR could mitigate membrane fouling. It was also identified here that the removal of dissolved organic matter (DOM) in MABR was accomplished through the combination of three unit effects: rejection by ultrafiltration (UF) membrane, biodegradation by microorganism, and adsorption by PAC; the last was of great importance. A sludge layer was observed on the membranes surface in both MABR and MBR and PAC particles themselves constituted a part of the cake layer and helped to intercept DOM in the mixed liquor by adsorption in MABR, especially for organic molecules of 5000–500 Da. The UF membrane together with the sludge layer and PAC layer in the MABR was able to reject hydrophobic bases (HoBs), hydrophobic neutrals, hydrophobic acids (HoAs), weakly hydrophobic acids (WHoAs) and hydrophilic matter (HiM) in the mixed liquor by 40.0%, 43.9%, 71.8%, 56.6% and 35.9%, respectively.

Seasonal variations of chemical and physical characteristics of dissolved organic matter and trihalomethane precursors in a reservoir: a case study

Dissolved organic matter (DOM) and its potential to form disinfection by-products (DBPs) during water treatment are of great public health concern. Understanding the seasonal changes in DOM composition and their reactivity in DBP formation could lead to a better treatment of drinking water and a more consistent water quality. DOM from the East-Lake, a reservoir in the south-China, was fractionated and characterized by XAD resin adsorption (RA) and ultrafiltration (UF) techniques during different seasons within a year. The properties of chemical fractions (isolated by RA) appeared more stable than those of physical fractions (separated by UF) throughout the sampling period. The relative contribution of each chemical fraction to the total dissolved organic carbon (DOC), UV 254 absorbance and trihalomethane formation potential (THMFP) remained relatively constant across the sampling period. However, the physical (molecular weight) fractions of the DOM exhibited large seasonal changes in UV 254 and THMFP. Compared to the parameter of DOC, the THMFP and specific THMFP (STHMFP) of either chemical or physical fractions were more variable. In terms of DOC concentration, the hydrophobic acids (HoA) and hydrophilic matter (HiM) dominated in the DOM in most of the seasons; while the components with molecular weight of 10–30 kDa and less than 1 kDa were the predominant physical fractions.

Physicochemical Investigation of Nanostructures in Liquid Phases: Ytterbium Nitrate Ionic Clusters Confined in Ytterbium Bis(2-ethylhexyl) Sulfosuccinate Reversed Micelles and Liquid Crystals

The confinement of finite amounts of ytterbium nitrate in the nanoscopic space of ytterbium bis(2-ethylhexyl)sulfosuccinate (Yb(DEHSS) 3 ) reversed micelles dispersed in n-heptane has been investigated by UV-vis-NIR, FT-IR, and SAXS. The analysis of the experimental data is consistent with the hypothesis that Yb(NO 3 ) 3 is distributed among reversed micelles as small size ionic clusters surrounded by the Yb 3+ surfactant counterions and anionic heads while the surfactant alkyl chains point toward the solvent medium. As a consequence of confinement and interfacial effects, the ionic clusters display photophysical properties different from those in the bulk state or isolated species. Moreover, the entrapment of Yb(NO 3 ) 3 involves some changes in the structural properties of reversed micelles attributable to the increase of the volume fraction of the hydrophilic matter confined in the micellar core. Preliminary WAXS experiments on Yb(NO 3 ) 3 /Yb(DEHSS) 3 composites obtained by complete evaporation of volatile components (water and organic solvent) of the liquid Yb(N03)3,water/Yb(DEHSS)3/n-heptane samples showed that also in these systems Yb(NO 3 ) 3 is dispersed in the hydrophilic domains of the surfactant matrix as very small clusters.

Seasonal Variation in the Chemical Composition and Condition Indices of Pacific Oyster, Crassostrea gigas, Grown in Trays or on the Sea Bed

Chemical composition and condition indices of tray and bottom-cultured Pacific oyster, Crassostrea gigas, were measured and compared over a 13-mo period. Tray oysters were less dense than bottom oysters as a result of increased porosity of shells. Dry meat condition indices were slightly higher in oysters grown in trays. Chloride and iodide levels peaked in early spring. Minor seasonal deviations occurred from the mean 61.0% polymeric matter, 31.5% hydrophilic matter of low molecular weight, and 7.5% lipid matter in both groups of oysters. Nonprotein to protein nitrogen ratio in tray and bottom oysters averaged 0.37 and 0.35, respectively, throughout the season. A procedure was developed to assess glycogen in situ in polymeric material fractionated from meat. Glycogen averaged 79.5 and 79.0% of the total glucose in tray and bottom oysters, respectively; the remainder consisted of the homologous series of α(1 → 4)-linked D-glucose oligomers. Degree of polymerization of oligosaccharides in tray and bottom oysters averaged 2.93 and 2.91, respectively. Dry meat condition indices correlated predominantly with protein condition indices, only secondarily with glycogen condition indices and insignificantly with the remaining constituent condition indices of tray and bottom oysters.Key words: Crassostrea gigas, tray and bottom cultures, chemical composition, nitrogen, carbohydrates, halides, density, condition indices, seasonal variations