Characteristics Of Natural Organic Matter Research Articles

Application of 3-D Fluorescence: Characterization of Natural Organic Matter in Natural Water and Water Purification Systems.

Natural organic matter (NOM) found in water sources is broadly defined as a mixture of polyfunctional organic molecules, characterized by its complex structure and paramount influence on water quality. Because the inevitable release of pollutants into aquatic environments due to an ineffective control of industrial and agricultural pollution, the evaluation of the interaction of NOM with heavy metals, nanoparticles, organic pollutants and other pollutants in the aquatic environment, has greatly increased. Three-dimensional (3-D) fluorescence has the potential to reveal the interaction mechanisms between NOM and pollutants as well as the source of NOM pollution. In water purification engineering system, the 3-D fluorescence can indicate the variations of NOM composition and gives an effective prediction of water quality as well as the underline water purification mechanisms. Inadequately treated NOM is a cause of precursors of disinfection byproducts (DBPs), posing a potential threat to human health. Effective control and measurement/evaluation of NOM have long been an important factors in the prevention of water pollution. Overall, 3-D fluorescence allows for a rapid identification of organic components thus indicating possible sources of water pollution, mechanisms of pollutant interactions, and possible DBPs formed during conventional treatment of this water. This article reviews the 3-D fluorescence characteristics of NOM in natural water and typical water purification systems. The 3-D fluorescence was effective for indicating the variabilities in NOM composition and chemistry thus providing a better understanding of NOM in natural water system and water engineering system.

Evaluation of natural organic matter adsorption on Fe-Al binary oxide: Comparison with single metal oxides

The adsorption characteristics of three types of standard natural organic matter (NOM) on iron-aluminum (Fe-Al) binary oxide (FAO) and heated aluminum oxide (HAO) under natural surface water condition were investigated using various adsorption isotherms and kinetic models. FAO was synthesized by Fe oxide and Al oxide, mixed using the sol-gel hydrothermal method, and aluminum sulfate was used to make HAO. The amount of adsorbed NOM was increased to 79.6 mg g−1 for humic acid (HA), 101.1 mg g−1 for sodium alginate (SA) in the FAO, but the maximum adsorption capacity of bovine serum albumin (BSA) (461.3 mg g−1) was identified on the HAO. The adsorption of HA, BSA, and SA dramatically increased (>70%) on FAO in 5 min and HA was significantly removed (90%) among the three NOM. Mutual interaction among the adsorbed NOM (BSA) occurred on the HAO surface during adsorption due to formation of monolayer by protein molecules at neutral pH. The pseudo second order clearly represented the adsorption kinetics for both adsorbents. The equilibrium isotherm data of FAO was better exhibited by the Langmuir isotherm model than by the Freundlich isotherm, but HAO was a slightly non-linear Langmuir type. Also, the free energy, enthalpy, and entropy of adsorption were determined from the thermodynamic experiments. Adsorption on FAO was spontaneous and an exothermic process. Fluorescence excitation-emission matrix (FEEM) spectra were used to elucidate the variation in organic components. The results obtained suggests that the significant changes in the surface property of the adsorbent (large surface area, increased crystalline intensity, and fine particle size) were effectively determined by the Fe-synthesized Al oxide mixed using the sol-gel hydrothermal method. The results also suggest that the changes enhanced the adsorption capacity, whereby three NOM were notably removed on FAO regardless of NOM characteristics (hydrophobic and hydrophilic).

Simulation of NOM events in pilot plant evaluation of DAF/Ozone/BAC for drinking water treatment

Abstract Pilot plant testing is invaluable for ascertaining the robustness of water treatment processes against raw water quality events such as turbidity and colour spikes, whether it be for stress testing of an existing process or designing of a new process. Unfortunately, the natural occurrence of such events (particularly colour) can be difficult to predict and commercial humic materials generally fail to closely match the indigenous natural organic matter (NOM) present in the raw water. Therefore, it is highly desirable to be able to simulate NOM event conditions. This paper describes a simple brewing method that we developed and used in our recent pilot plant evaluation of a proposed DAF/Ozone/BAC process for drinking water treatment. Using this method we successfully prepared, by using fallen leaves etc. collected from the local catchment area, large quantities of a concentrated NOM stock solution with its specific ultraviolet absorbance (SUVA), when diluted, very close to the median SUVA of historical NOM events. The brewed solution showed broadly similar NOM characteristics to those of the raw water encountered during the pilot investigation period in terms of molecular weight distribution and fractionation. The coagulation behaviour was also examined for the spiked and non-spiked raw water.

Effect of potassium permanganate dosing position on the performance of coagulation/ultrafiltration combined process

Abstract The effects of potassium permanganate (KMnO 4 ) dosing position on the natural organic matter (NOM) removal as well as membrane fouling were investigated in the coagulation/ultrafiltration combined process. KMnO 4 oxidation altered the NOM characteristics in terms of hydrophobicity and molecular weight, and destroyed humic substances originated from terraneous organisms in raw water. The optimal KMnO 4 dosage was 0.5 mg·L − 1 in the peroxidation enhanced coagulation process with respect to the dissolved organic carbon (DOC) removal. When KMnO 4 was dosed into both upstream and downstream of coagulation, namely in the proposed two-position dosing mode, coagulation and KMnO 4 oxidation worked individually on the apparent DOC removal. However, compared to the KMnO 4 addition prior to or after coagulation, the two-position dosing mode dramatically alleviated membrane fouling and reduced fouling irreversibility. This was attributed to the change of NOM characteristics as a result of KMnO 4 addition prior to coagulation and the presence of MnO 2 on membrane surface as a result of KMnO 4 addition prior to ultrafiltration. This work may provide useful information for the application of KMnO 4 oxidation in the coagulation/ultrafiltration combined system.

Seasonally related effects on natural organic matter characteristics from source to tap in Korea

In this study, natural organic matter (NOM) characteristics were investigated over three years of monthly monitoring to determine the effect of seasonal variations on NOM levels from source to tap. Liquid chromatography with organic carbon detection (LC-OCD) was used to determine NOM characteristics and the level of reduction of biodegradable dissolved organic carbon (BDOC). The average dissolved organic matter concentration in the source water (Lake Paldang, Korea) was not significantly different between summer and winter. However, the distribution of NOM components, such as biopolymers, building blocks, low molecular weight (MW) neutrals and acids, identified by LC-OCD, varied seasonally. While high MW NOM was preferentially removed by coagulation/sedimentation/rapid sand filtration (CSR), no seasonal effects were observed on the removal of high MW NOM. CSR and biological activated carbon (BAC) filtration showed a better efficiency of BDOC removal in winter and summer, respectively. High concentrations of chlorine used in the treatment plants in summer resulted in 10% higher DOC concentrations during disinfection. Overall NOM removal efficiencies from source to tap were 45% and 35% for summer and winter, respectively. Principal component analysis also indicated that seasonal variations (principal component 1) showed the strongest positive correlation with the overall performance of water treatment. The long-term monitoring of drinking water treatment processes showed that seasonal variations were important factors affecting NOM characteristics during water treatment.

Investigation of natural organic matter (NOM) character and its removal in a chlorinated and chloraminated system at Rand Water, South Africa

In its natural environment, natural organic matter (NOM) is not problematic. However, during water treatment NOM does affect water quality specifically during the disinfection step, where if NOM is present it reacts with disinfectants resulting in the formation of disinfection by-products. To emphasize the importance of NOM monitoring during potable water treatment this study aimed to characterize NOM and evaluate NOM removal by a conventional water treatment plant considering seasonal trends. NOM was characterized by making use of NOM polarity and specific ultraviolet absorbance. NOM removal was monitored with high-performance size exclusion chromatography, dissolved organic carbon (DOC) and UV254 analyses. The polarity rapid assessment method indicated that the hydrophobic and hydrophilic NOM fractions within the surface water increased during a period of heavy rain when floods occurred, but conversely decreased during an average rain season. Although NOM character showed variability during the 5-year study period, seasonal relationship during high and low flow seasons between aromatic NOM and total trihalomethane (TTHM) formation was not evident. Aromatic NOM was not the only precursor to TTHM formation, which stresses the need to implement advanced NOM characterization techniques during NOM monitoring to study reactivity of the individual NOM fraction with the disinfectant used at the water treatment plant.

Investigation of ozone and peroxone impacts on natural organic matter character and biofiltration performance using fluorescence spectroscopy

Impacts of ozonation alone as well as an advanced oxidation process of ozone plus hydrogen peroxide (H2O2 + O3) on organic matter prior to and following biofiltration were studied at pilot-scale. Three biofilters were operated in parallel to assess the effects of varying pre-treatment types and dosages. Conventionally treated water (coagulation/flocculation/sedimentation) was fed to one control biofilter, while the remaining two received water with varying applied doses of O3 or H2O2 + O3. Changes in organic matter were characterized using parallel factors analysis (PARAFAC) and fluorescence peak shifts. Intensities of all PARAFAC components were reduced by pre-oxidation, however, individual humic-like components were observed to be impacted to varying degrees upon exposure to O3 or H2O2 + O3. While the control biofilter uniformly reduced fluorescence of all PARAFAC components, three of the humic-like components were produced by biofiltration only when pre-oxidation was applied. A fluorescence red shift, which occurred with the application of O3 or H2O2 + O3, was attributed to a relative increase in carbonyl-containing components based on previously reported results. A subsequent blue shift in fluorescence caused by biofiltration which received pre-oxidized water indicated that biological treatment readily utilized organics produced by pre-oxidation. The results provide an understanding as to the impacts of organic matter character and pre-oxidation on biofiltration efficiency for organic matter removal.

Characteristics of NOM Released to Water from Different Forest and Agricultural Soils

The characteristics of natural organic matter (NOM) released to water from a soil environment were investigated based on the release potential and the quality indexes of SUVA, fluorescence EEM and molecular weight distribution using eight forest and agricultural soils collected from a representative river catchment (Kani River catchment in Gifu, Japan). The content of organic matter (OM) and its release potential to water differed obviously with type of soil origin, in the following order: vegetable field (VF) basic condition [3.5-8.0 m -1 /(mg/L)] > acidic condition [2.5-3.0 m -1 /(mg/L)]. Humic acids (P1), fulvic acids (P2) and protein-like substances (P3) were the main components of the NOM released under neutral condition. The proportion of P1 and P2 released from the forest soils was lower than that from the agricultural soils. Marked differences in UV-absorbing constituents of NOM between forest and agricultural soils were found in the peak with a molecular weight of about 9800 g/mol identified as PSS (polystyrene sulfonate).

Modeling and characterization of natural organic matter and its relationship with the THMs formation

<p>Natural organic matter (NOM) has been identified as the prominent precursor for disinfection by-products (DBPs) formation during chlorination. Various studies have shown that the characteristics of NOM influence the Trihalomethanes (THMs) formation mechanism. The present study represents NOM categorization in terms of total organic carbon (TOC), dissolved organic carbon (DOC), UV absorbance at 254 nm wavelengths (UV<sub>254</sub>) and specific ultraviolet absorbance (SUVA) to investigate the effects of NOM on THMs formation mechanism. The high rate of dependency was found for each representative of NOM with respect to water quality characteristics and operational condition of disinfection process. Values of SUVA and UV<sub>254</sub> is drastically reduced with respect from higher to a moderate chlorine dose which represent the chlorine contact is more predominant with hydrophobic fractions of NOM. The value of SUVA is decreasing with respect to temperature and reaction time, which reveled higher rate of utilization for hydrophobic fractions of NOM. Predictive modeling approach was carried out using multiple regression analysis with the combination of two surrogates at each stage of modeling with help of operational condition of disinfection process and water quality characteristics. The R<sup>2</sup> value of the model was found in the range of 0.927 to 0.937 from the developed model and a model could be recommended for prediction of THMs in drinking water.</p>

Quantity and quality of natural organic matter influence the ecotoxicity of titanium dioxide nanoparticles

Nanoparticles’ fate is amongst other parameters determined by the quantity and quality of natural organic matter (NOM). Consequently, the ecotoxicity of nanoparticles is modified, while only little information is available on the NOM characteristics triggering this interplay. This study systematically examined how NOM quantity and quality influences the acute ecotoxicity of titanium dioxide nanoparticles (nTiO2) towards Daphnia magna. Therefore, two nTiO2 products (A-100 and P25; ∼100 nm) were investigated in combination with seven NOM types of variable quality at four levels each (up to 4.00 mg total organic carbon/L). The results showed that – independent of the applied nTiO2 product and NOM type – nTiO2 ecotoxicity decreased up to a factor of >18 with increasing NOM concentration. More importantly, increasing levels of aromaticity and hydrophobicity of the NOM decreased the magnitude of toxic effects caused by nTiO2, which was again independent of the nTiO2 product tested. In the light of the ubiquitary presence of NOM, the ecotoxicological risk of nTiO2 in surface waters with high NOM loads is likely moderate. However, interactions of nTiO2 and NOM in combination with other natural or chemical stressors are not well-understood but seem to be fundamental for a reliable risk assessment of nanoparticles.

Influences of NOM composition and bacteriological characteristics on biological stability in a full-scale drinking water treatment plant

The influences of natural organic matter (NOM) and bacteriological characteristics on the biological stability of water were investigated in a full-scale drinking water treatment plant. We found that prechlorination decreased the hydrophobicity of the organic matter and significantly increased the high-molecular-weight (MW) dissolved organic matter, such as biopolymers and humic substances. High-MW organic matter and structurally complex compounds are known to be relatively slowly biodegradable; however, because of the prechlorination step, the indigenous bacteria could readily utilise these fractions as assimilable organic carbon. Sequential coagulation and sedimentation resulted in the substantial removal of biopolymer (74%), humic substance (33%), bacterial cells (79%), and assimilable organic carbon (67%). Rapid sand and granular activated carbon filtration induced an increase in the low-nucleic-acid content bacteria; however, these bacteria were biologically less active in relation to enzymatic activity and ATP. The granular activated carbon step was essential to securing biological stability (the ability to prevent bacterial growth) by removing the residual assimilable organic carbon that had formed during the ozone treatment. The growth potential of Escherichia coli and indigenous bacteria were found to differ in respect to NOM characteristics. In comparison with E. coli, the indigenous bacteria utilised a broader range of NOM as a carbon source. Principal component analysis demonstrated that the measured biological stability of water could differ, depending on the NOM characteristics, as well as on the bacterial inoculum selected for the analysis.

Characterization of iodinated disinfection by-products in chlorinated and chloraminated waters using Orbitrap based gas chromatography-mass spectrometry.

Recent developments in gas chromatography (GC)-mass spectrometry (MS) have opened up the possibility to use the high resolution-accurate mass (HRAM) Orbitrap mass analyzer to further characterize the volatile and semivolatile fractions of environmental samples. This work describes the utilization of GC Orbitrap MS technology to characterize iodine-containing disinfection by-products (iodo-DBPs) in chlorinated and chloraminated DBP mixture concentrates. These DBP mixtures were generated in lab-scale disinfection reactions using Llobregat river water and solutions containing Nordic Lake natural organic matter (NOM). The DBPs generated were concentrated using XAD resins, and extracts obtained were analyzed in full scan mode with the GC Orbitrap MS. Integration of high resolution accurate mass information and fragment rationalization allowed the characterization of up to 11 different iodo-DBPs in the water extracts analyzed, including one new iodo-DBP reported for the first time. Overall, formation of iodo-DBPs was enhanced during chloramination reactions. As expected, NOM characteristics and iodide and bromide content of the tested waters affected the amount and type of iodo-DBPs generated.

Effect of phosphorus addition on biofiltration pre-treatment to reduce ultrafiltration membrane fouling

A pilot-scale study investigated the effect of phosphorus addition on a drinking water biofilter used to reduce fouling of an ultrafiltration membrane. Biofiltration without pre-treatment (BFwp) has been shown to be an effective pre-treatment for the removal of natural organic matter (NOM) components that cause membrane fouling. However, the river source used in this study was found to have low phosphorus concentrations that could potentially affect biofilter biomass levels and NOM biodegradation. The river water source (Saugeen River located at Walkerton, Ontario, Canada) had a high total organic carbon (4.34–6.61 mg/L) of primarily humic content, variable turbidity, and seasonal changes in water temperature (9.7–19.9°C) as measured over the study period. Phosphorus was added to the biofilter influent at 0.01 mg P/L, and later at 0.05 mg P/L, over a four-month period. Biofilter activity, NOM removal, and membrane performance were compared to a control system operating under identical conditions but without nutrient addition. Filter biomass measured by ATP and fluorescein diacetate hydrolysis (overall enzyme activity) was stable over time, with no difference between control and phosphorus-amended biofilters. As well, phosphorus addition did not improve the removal of NOM fractions, especially biopolymers that are important for membrane fouling. There was a small initial increase in the removal of dissolved organic carbon and humic substances after phosphorus addition, but this effect diminished over time. The effluent from each biofilter was used to operate an ultrafiltration membrane system using conditions similar to full scale. Membrane fouling for each experiment was measured over 1.5 d, and operating cycles included 30-min permeation followed by backwashing/air sparging. Results showed that there was no difference in hydraulically reversible or irreversible fouling of membranes fed with the effluent from control or phosphorus-amended biofilters. It was found that biofilter nutrient feed requirements are likely site specific, and affected by factors including biomass and NOM characteristics.

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

The effects of pre-ozonation on ultrafiltration (UF) membrane fouling caused by different natural organic matter (NOM) fractions were investigated. Three typical organic model foulants, humic acid (HA), sodium alginate (SA) and bovine serum albumin (BSA) were selected as representatives of different NOM fractions in natural waters. Moreover, Songhua River water (SRW) was employed as a natural surface water. To predict membrane fouling, the dissolved organic carbon (DOC), ultraviolet absorbance (UV254) and the maximum fluorescence intensity (Fmax) were used to establish correlations with total fouling index (TFI) and hydraulic irreversible fouling index (HIFI). In addition, the fouling mechanisms were preliminarily analyzed. The results indicated that pre-ozonation significantly alleviated membrane fouling caused by HA, SA and SRW. Maximum ozone dose (4.0mg/L) showed the best performance with approximately 39%, 78% and 42% TFI reduction, and 26%, 73% and 39% HIFI reduction for HA, SA and SRW, respectively. However, pre-ozonation exerted little influence on BSA fouling under the tested ozone exposure (0.5, 1.5 and 4.0mg/L). TFI and HIFI were poorly correlated with the DOC contents of HA, SA, BSA and SRW, and the Fmax of BSA, whereas positively correlated with the UV254 of HA and SRW, and the Fmax of HA and each component of SRW. The fouling mitigation mechanisms were attributed to the changes of NOM properties after pre-ozonation. The results are expected to provide relevant information on predicting and controlling UF membrane fouling according to the composition and characteristics of NOM.

Characteristics of natural organic matter removed from water along with its treatment

Characteristics of natural organic matter removed from water along with its treatment

Characteristics of natural organic matter removed from water along with its treatment

Characteristics of natural organic matter removed from water along with its treatment

Correlating the chemical and spectroscopic characteristics of natural organic matter with the photodegradation of sulfamerazine

The role of aquatic natural organic matter (NOM) in the removal of contaminants of emerging concern has been widely studied. Sulfamerazine (SMR), a sulfonamide antibiotic detected in aquatic environments, is implicated in environmental toxicity and may contribute to the resistance of bacteria to antibiotics. In aquatic systems sulfonamides may undergo direct photodegradation, and, indirect photodegradation through the generation of reactive species. Because some forms of NOM inhibit the photodegradation there is an increasing interest in correlating the spectroscopic parameters of NOM as potential indicators of its degradation in natural waters.Under the conditions used in this study, SMR hydrolysis was shown to be negligible; however, direct photolysis is a significant in most of the solutions studied. Photodegradation was investigated using standard solutions of NOM: Suwannee River natural organic matter (SRNOM), Suwannee River humic acid (SRHA), Suwannee River fulvic acid (SRFA), and Aldrich humic acid (AHA). The steady-state concentrations and formation rates of the reactive species and the SMR degradation rate constants (k1) were correlated with NOM spectroscopic parameters determined using UV–vis absorption, excitation-emission matrix (EEM) fluorescence spectroscopy, and proton nuclear magnetic resonance (1H NMR).SMR degradation rate constants (k1) were correlated with steady-state concentrations of NOM triplet-excited state ([3NOM∗]ss) and the corresponding formation rates (3NOM*) for SRNOM, SRHA, and AHA. The efficiency of SMR degradation was highest in AHA solution and was inhibited in solutions of SRFA. The steady-state concentrations of singlet oxygen ([1O2]ss) and the SMR degradation rate constants with singlet oxygen (k1O2) were linearly correlated with the total fluorescence and inversely correlated with the carbohydrate/protein content (1H NMR) for all forms of NOM. The total fluorescence and EEMs Peak A were confirmed as indicators of 1O2 formation. Specific ultraviolet absorbance at 254 nm (SUVA254) and aromaticity showed potential correlations with the steady-state concentrations of hydroxyl radical ([HO]ss) and the corresponding formation rates (HO).

Fate of natural organic matter at a full-scale Drinking Water Treatment Plant in Greece.

The aim of this study was to investigate the fate of natural organic matter (NOM) and subsequent changes during the various treatment processes at a full-scale Drinking Water Treatment Plant (DWTP). Monthly sampling campaigns were conducted for 1 year at six sites along DWTP of Thessaloniki, Northern Greece including raw water from the Aliakmonas River that supplies DWTP and samples from various treatment processes (pre-ozonation, coagulation, sand filtration, ozonation, and granular activated carbon (GAC) filtration). The concentration of NOM and its characteristics as well as the removal efficiency of various treatment processes on the basis of dissolved organic carbon, UV absorbance, specific ultra-violet absorbance, fluorescence intensity, hydrophobicity, biodegradable dissolved organic carbon, and formation potential of chlorination by-products trihalomethanes (THMs) and haloacetic acids (HAAs) were studied. The concentration of dissolved organic carbon (DOC) in reservoir of the Aliakmonas River ranged from 1.46 to 1.84 mg/L, exhibiting variations regarding UV, fluorescence, and hydrophobic character through the year. Along DWTP, a significant reduction of aromatic, fluorophoric, and hydrophobic character of NOM was observed resulting in significant elimination of THM (63%) and HAAs (75%) precursors.

The removal characteristics of natural organic matter in the recycling of drinking water treatment sludge: Role of solubilized organics

To clarify the role of solubilized organics derived from drinking water treatment sludge (DWTS) in the elimination of natural organic matter (NOM) in the DWTS recycling process, a probe sonoreactor at a frequency of 25kHz was used to solubilize the organics at varied specific energies. The coagulation behavior related to NOM removal in recycling the sonicated DWTS with and without solubilized organics was evaluated, and the effect on organic fractionations in coagulated water was determined. The study results could provide useful implications in designing DWTS recycling processes that avoid the enrichment of organic matter. Our results indicate that DWTS was disrupted through a low release of soluble chemical oxygen demand (SCOD) and proteins, which could deteriorate the coagulated water quality under the specific energy of 37.87–1212.1kWh/kgTS. The optimal coagulation behavior for NOM removal was achieved by recycling the sonicated DWTS without solubilized organics at 151.5kWh/kgTS specific energy. Recycling the sonicated DWTS could increase the enrichment potential of weakly hydrophobic acid, hydrophilic matter, and <3kDa fractions; the enrichment risks could be reduced by discharging the solubilized organics. Fluorescent characteristic analysis indicated that when recycling the sonicated DWTS without solubilized organics, the removal of humic-like substances was limited, whereas removal of protein-like substances was enhanced, lowering the enrichment potential of protein-like substances.

Fouling characteristics of NOM during the ceramic membrane microfiltration process for water treatment

Ceramic membrane filtration is one of the most promising membrane technologies used for advanced water treatment. Many studies of the fouling behavior of natural organic matter (NOM) have been conducted, but membrane fouling due to dissolved organic matter remains a critical problem preventing the efficient operation of ceramic microfiltration (MF) in water treatment. The aim of this study was to evaluate the fouling characteristics of NOM during ceramic MF using pilot-scale ceramic membrane equipment. In experiments to characterize this fouling behavior, humic acid (HA), bovine serum albumin (BSA), and sodium alginate (SA) were used as representatives of humic substances, proteins, and polysaccharides, respectively. In particular, we evaluated the effects of several parameters on the fouling characteristics of NOM, including concentration, foulant mixture, and rate of flux recovery. The flux decline in the presence of SA showed that ceramic membrane fouling occurred immediately. The membrane fouling by HA was well explained by a linear regression equation. More interestingly, BSA was found to cause mainly irreversible fouling, which is significant because this mechanism involves internal pore adsorption through particle superposition due to foulant accumulation on the membrane surface. The results indicate that the different fouling behaviors of the three types of macromolecules are distinct due to their apparent physical–chemical characteristics.