Natural Organic matter (NOM)

Due to health concerns of natural organic matter (NOM) and algae presence in surface water and difficulties encountered in their removal in the water treatment, this paper reviews coagulation and chlorination processes which are largely used in water treatment technology. In the conventional water treatment, coagulation and slow filtration treatments have better efficiency to reduce the NOM in water especially for the hydrophobic portion than the hydrophilic one. However, the pre-chlorination treatment for raw water has been proved to increase the dissolved organic carbon concentration due to the lysis of algae cells and disinfection by-products formation. The impact of water treatment processes on disinfection byproducts formation remains complex and variable, as demonstrated by recent literature. It is concluded that no pre-, no inter-, only post-chlorination preceded by optimised coagulation for NOM and algae removal is the best available technology for the conventional water treatment which would be reinforced by at least adsorption on powdered activated carbon or nanofiltration in the short terms. Finally, the conventional water treatment will not remain a viable solution for drinking water from source waters containing NOM as their quality deteriorates and water quality standards become more difficult to achieve.

The generation, monitoring, and health impacts of disinfection by-products (DBPs) in potable water are problems of worldwide worry. Several nations, besides the World Health Organization, possess regulations and/or guidelines on bearable levels of DBPs in water. Since drinking water is frequently remediated using a chemical killing agent, DBPs are pollutants to which several humans are unprotected. On account of the health impacts linked to subjection to chlorinated water and/or some DBPs, the water manufacturing has performed great endeavors to equilibrate killing pathogens and DBP monitoring. Large survey has been realized on rising DBPs of health and regulatory worry. In spite of the fact that the attention on DBPs was previously on chlorine-and bromine-containing carbonaceous DBPs, appearing DBPs comprise iodine-containing species, also halogenated and non-halogenated nitrogenous DBPs. In addition, latest toxicity experimentation has proposed that certain of the more recent PBPs are of more elevated toxicity than some of the regulated chemical products. Therefore, survey has been realized to better comprehend how to cost-effectively monitor a large interval of regulated and appearing DBPs. This comprises the usage of advanced remediation and killing pathogens methodologies. This paper shows certain of the newest research works at comprehending these significant DBP-related problems. Disinfection is killing microorganisms present in water; but, it is as well killing human beings drinking water by poisonous DBPs. Using chemicals for water treatment is finally a lost cause.

Advances in water chemistry in the last decade have improved our knowledge about the genesis, composition , and structure of dissolved organic matter, and its effect on the environment. Improvements in analytical technology, for example Fourier-transform ion cyclo-tron (FT-ICR) mass spectrometry (MS), homo and hetero-correlated multidimensional nuclear magnetic resonance (NMR) spectroscopy, and excitation emission matrix fluorimetry (EEMF) with parallel factor (PARAFAC) analysis for UV–fluorescence spectroscopy have resulted in these advances. Improved purification methods, for example ultrafiltration and reverse osmosis, have enabled facile desalting and concentration of freshly collected DOM samples, thereby complementing the analytical process. Although its molecular weight (MW) remains undefined, DOM is described as a complex mixture of low-MW substances and larger-MW biomo-lecules, for example proteins, polysaccharides, and exo-cellular macromolecules. There is a general consensus that marine DOM originates from terrestrial and marine sources. A combination of diagenetic and microbial processes contributes to its origin, resulting in refractory organic matter which acts as carbon sink in the ocean. Ocean DOM is derived partially from humified products of plants decay dissolved in fresh water and transported to the ocean, and partially from proteinaceous and poly-saccharide material from phytoplankton metabolism, which undergoes in-situ microbial processes, becoming refractory. Some of the DOM interacts with radiation and is, therefore, defined as chromophoric DOM (CDOM). CDOM is classified as terrestrial, marine, anthropogenic, or mixed, depending on its origin. Terrestrial CDOM reaches the oceans via estuaries, whereas autochthonous CDOM is formed in sea water by microbial activity; anthropogenic CDOM is a result of human activity. CDOM also affects the quality of water, by shielding it from solar radiation, and constitutes a carbon sink pool. Evidence in support of the hypothesis that part of marine DOM is of terrestrial origin, being the result of a long-term carbon sedimentation, has been obtained from several studies discussed herein.

The scientific understanding of the molecular size and shape of humic
substances (HS) is critically reviewed. The traditional view that HS are
polymers in soil is not substantiated by any direct evidence but is assumed
only on the basis of laboratory experiments with model molecules
and unwarranted results produced by incorrectly applying either analytical
procedures or mathematical treatments developed for purified and
undisputed biopolymers. A large body of evidence shows an alternative
understanding of the conformational nature of HS, which should be regarded
as supramolecular associations of self-assembling heterogeneous
and relatively small molecules deriving from the degradation and decomposition
of dead biological material. A major aspect of the humic
supramolecular conformation is that it is stabilized predominantly by
weak dispersive forces instead of covalent linkages. Hydrophobic (van
der Waals,
-
, CH-
) and hydrogen bonds are responsible for the apparent
large molecular size of HS, the former becoming more important
with the increase of pH. This innovative understanding of the nature of
HS implies a further development of the science and technology for the
control of the chemistry and reactivity of natural organic matter in the
soil and the environment. (Soil Science 2001; 166:810–832)

This work aims to study the physicochemical and biological parameters of Boukerdene Dam's water and treated water at different steps of the treatment processes in Sidi-Amar's Station (Tipaza, Algeria) with a particular interest to the phytoplankton. This work is also related to the demonstration of the enhanced coagulation (EC) process as an efficient method in algae and organic matter (OM) removal from surface water by its application in jar tests. The diversity of the phytoplankton shows the presence of 21 genera comprising 30 algae species out of 8 samples taken from the Boukerdene Dam. Among the identified genera, seven of them are responsible for the unpleasant tastes and odours of water; six others are responsible for filter fouling. Generally, the conventional drinking water treatment processes employed at this water treatment plant shows a limited efficiency of OM and algae removal. The novelty of this work is that the jar tests of EC (pH 6 and alum dose 15 mg L-1) as only one stage of water treatment, without chlorination and filtration, improve the removal of OM and algae at 97 to 99%, respectively.

"This review discusses the hydrophilic/hydrophobic ratio as a function of the hydrophilic
and hydrophobic contents removal by coagulation process. It is well established that coagulation
process could bring a reduction in dissolved organic carbon of around 30–60% by increasing the
coagulant dose and optimising reaction pH, in which large organic molecules with hydrophobic
property was removed preferentially. Furthermore, the literature affirmed that the greater removal
of UV-absorbing substances indicates that alum coagulation preferentially removed the hydrophobic
fraction of the total organic carbon. For the hydrophobic fraction, it needs to be removed
entirely without its transformation into hydrophilic fractions by coagulation process avoiding
pre-chlorination/pre-oxidation due to the risk of organic molecules fragmentation. Determining
the exact numerical values of the hydrophilic/hydrophobic ratio for raw water and treated water
at different stages of the treatment processes in a water treatment plant, as for the DCO/DBO5 ratio
in the case of wastewater treatment, would help on more focusing on OM control and removal"

Due to health concerns of natural organic matter (NOM) and algae presence in surface water and difficulties encountered in their removal in the water treatment, this paper reviews coagulation and chlorination processes which are largely used in water treatment technology. In the conventional water treatment, coagulation and slow filtration treatments have
better efficiency to reduce the NOM in water especially for the hydrophobic portion than the hydrophilic one. However, the
pre-chlorination treatment for raw water has been proved to increase the dissolved organic carbon concentration due to the
lysis of algae cells and disinfection by-products formation. The impact of water treatment processes on disinfection byproducts formation remains complex and variable, as demonstrated by recent literature. It is concluded that no pre-, no inter-, only post-chlorination preceded by optimised coagulation for NOM and algae removal is the best available technology for the conventional water treatment which would be reinforced by at least adsorption on powdered activated carbon or nanofiltration in the short terms. Finally, the conventional water treatment will not remain a viable solution for drinking water from source waters containing NOM as their quality deteriorates and water quality standards become more difficult to achieve.

Since the 1970s' disinfection by-products (DBPs) detection, the water treatment specialists' main focuses were accorded to the DBPs formation, characterization, regulations and control. Involved stages in disinfection process were at a certain level kept at the side as a black box. This paper is a broad review on chlorination applied in water treatment technology especially in terms of involved mechanisms. Chlorine occasions significant injury to bacterial cells, cell permeability dislocation and nucleic acids and enzymes injury. Hypochlorous acid oxidizes sulfhydryl groups, harms iron-sulfur centers, deactivates nutrient transport, hinders cell respiration, and deteriorates the capacity of cells to keep a sufficient adenylate energy charge to stay viable. All disinfectants are highly efficient killing agents. However, these chemical products are very toxic by their selves. Moreover, they interact with NOM, microorganisms, and algae to produce DBPs which are as well poisonous. Consequently, the use of disinfectants must be avoided upon using physical processes or at least reduced as possible at the lowest level.

In many agricultural soils in the semi-arid and arid mediterranean climates, exposure to cyclic wetting and drying (WD) can reduce aggregate stability. The extent to which soil pretreatment with coal-derived humic substances (HS) can increase aggregate stability in soils exposed to cyclic wetting and drying (WD) was evaluated in this study. The soils studied are an Acireale silty clay loam from Sicily, a Principina silt loam from Tuscany and a Bovolone loam from Venetia in Italy. On each soil eight rates of the HS (0, 0.001, 0.01, 0.05, 0.10, 0.50, 1.00 and 10.00 g/kg of soil) and four WD cycles (0, 3, 6 and 9) were used to assess any changes in stability.

Natural organic matter poses an increasing challenge towatermanagers because of its potential adverse impacts
on water treatment and distribution, and subsequently human health. Projections were made of impacts of climate
change on dissolved organic carbon (DOC) in the primarily agricultural Boyne catchment which is used
as a potablewater supply in Ireland. The results indicated that excluding a potential rise in extreme precipitation,
future projected loads are not dissimilar to those observed under current conditions. This is because projected increases
in DOC concentrations are offset by corresponding decreases in precipitation and hence river flow. However,
the results presented assume no changes in land use and highlight the predicted increase in DOC loads from
abstracted waters at water treatment plants.

Fox River water was supersaturated with respect to calcite; natural organic matter (NOM) might play a key role in this phenomenon. Fox River NOM (FRNOM) adsorption on the calcite surface is probably an important mechanism to explain this condition. Fox River water contained moderate ultraviolet absorbance (UVA) of NOM (0.19 1/cm), high concentration of calcium (70 mg/L), suspended solids with relatively high specific surface area (SSA) (6.9 m2/g), and moderate pH value (8.4) based on historical data. To test whether the phenomenon was caused by NOM adsorption, a series of experiments was conducted to explore the interaction between NOM and calcite in conditions similar to those of the Fox River. Suwannee River NOM (SRNOM) and Nordic Reservoir NOM (NRNOM) were used as surrogate NOM. The results show that SRNOM inhibited calcite dissolution significantly after 10 min based on measuring of the decrease in the free calcium concentration. The decrease in the free calcium was not solely due to formation of NOM-calcium complexes, because these complexes made up only about 3% of the total free calcium concentration. Therefore, NOM adsorption onto calcite was probably largely responsible for the inhibited calcite activity. Experimental results also showed that NOM adsorption increased with increasing NOM concentration in the range from 2 to 14 mg NOM/L, which is a common range for river water. Higher charge density also seems to promote sorption onto calcite; relative to NRNOM, SRNOM has a higher charge density and SRNOM has a higher affinity for calcite. Other factors that promoted NOM adsorption onto calcite included higher concentration of calcium and larger SSA of calcite seed. Based on water quality characteristics, the Fox River provides a suitable environment for NOM adsorption on calcite, and it seems likely that Fox River NOM (FRNOM) adsorption on calcite can inhibit calcite precipitation. This understanding of interaction between NOM and calcite could be used by WTPs along the Fox River for better optimization and improvement in treatment and operation

We propose a mild stepwise fractionation of molecular components of a humic acid (HA) suprastructure and their structural identification by advanced analytical methods. This procedure may be the basis of a "Humeomics" approach to characterize natural humic molecules and clarify their relations with ecosystems functions. Sequential fractionation included: (1) organic solvent extraction, (2) transesterification with boron trifluoride in methanol (BF 3 -CH 3 OH), (3) methanolic alkaline hydrolysis (KOH-CH 3 OH), and (4) cleavage of ether and glycosidic bonds with HI. Structural identification of initial and final material, separated organo-soluble and hydrosoluble fractions, and subfractions was conducted by GC-MS, HPSEC-ESI-MS (high-resolution, Orbitrap), and solid-and liquid-state NMR. GC-MS revealed in organosoluble unbound fractions the presence of both saturated and unsaturated, linear and branched, alkanoic, hydroxyalkanoic and alkandioic acids, n-alkanes, and n-alkanols. These components decreased progressively in fractions obtained after weak and strong ester cleavage. Unsubstituted alkanoic acids with variable chain length were ubiquitously detected in all fractions, thereby suggesting their fundamental function in the architecture of humic suprastructures. An important role in differentiating supramolecular associations should also be attributed to substituted alkanoic acids that were detected in variable amounts in different fractions. The content of aromatic acids and steroids was only noticed in the latter fractions. HPSEC-ESI-MS of initial and final solid fractions showed similar compounds, as indicated by GC-MS, whereas the hydrosoluble fraction after transesterification revealed fewer of these compounds but noticeable nitrogen-containing acids. A large amount of "cyclic" acids were identified by MS empirical formula in initial HA, and, to a lesser extent, in the final fractionation residue as well as in the hydrosoluble fraction. The predominant alkyl NMR signals in organosoluble extracts and those of CH-N, CH-O, and O-CH-O groups in hydrosoluble fraction confirmed mass spectrometry results. Homo-and heterocorrelated liquid-state NMR spectra indicated spin systems interactions varying with separated fractions. Solid-state and dipolar-dephasing NMR spectra of final residue showed predominance of sp 2 carbons, 66% of which were quaternary carbons, and a significant increase in conformational rigidity with respect to initial HA. Separated fractions accounted for 60% of initial HA weight, and losses were attributed to hydration water, liberated volatile compounds, and decarboxylation. Quantization of analytes showed that the sum of compound classes in separated fractions was greater than that for the initial HA, thereby showing that stepwise fractionation increased significantly the analytical identification of humic molecules. Our results suggest this "Humeomics" approach as a valid path for mapping humic molecular composition and assess humus origin and formation.

Ten years ago, I was asked by a health agency about my opinion concerning the guidelines for drinking water quality. I suggested fixing the maximum acceptable concentration (MAC) to zero ng/L, once and for all for each pollutant. Such a proposition is founded on the fact that regularly the MAC is lowered following some considerations like 1) the lethal dose determination and toxicity studies, 2) the progress recorded in analytical methods and water treatment technologies and, 3) the technical-economic features of the country. Attaining the zero ng/L target is related to applying the best available technologies such as those used in the International Space Station. This work focuses on the hard challenges in dealing with the disinfection by-products (DBPs). This work concludes that, in terms of poisoning, un-regulated products vs. regulated products, the question does not matter. DBPs formation should be absolutely avoided. Moreover, if DBPs are un-wantedly produced, all of them must be securely removed from the water at the highest level as other organic matters. Finally, disinfection is killing microorganisms present in water; but, it is also killing human beings drinking water via its inherent toxic DBPs. Treating chemically water should be avoided.

Electrocoagulation (EC) is a flourishing technique in the field of water treatment implementations. Numerous investigations have been performed to assess the performance of EC to eliminate different pollutants; however, the more basic electrochemical features of the technique are usually ignored. Scientists such as McBeath et al. [1] provided an understanding of the essential link of water flow, electrochemical metal dissolution, and current density distribution (CDD) via computational fluid dynamic (CFD) models, mathematical models, and in situ CDD determination tests. They established, in theory, that current distributed over the electrode was inversely proportional to the water flow rate. By means of the CFD models and current distribution determining technique, they noted that current density was distributed unequally and pursued the tendency anticipated via theory. Eliminating natural organic matter was decreased as much as 79% when the inter-electrode distance was diminished from 10 to 1 mm. As a perspective, more efforts are required to better understand the CDD at the anodes surface and electric charges transfer from electrodes to the bulk of the solution. Mechanisms related to interactions of anodic metallic cations and various pollutants should be more investigated.

In many agricultural soils in the semi-arid and arid mediterranean climates, exposure to cyclic wetting and drying (WD) can reduce aggregate stability. The extent to which soil pretreatment with coal-derived humic substances (HS) can increase aggregate stability in soils exposed to cyclic wetting and drying (WD) was evaluated in this study. The soils studied are an Acireale silty clay loam from Sicily, a Principina silt loam from Tuscany and a Bovolone loam from Venetia in Italy. On each soil eight rates of the HS (0, 0.001, 0.01, 0.05, 0.10, 0.50, 1.00 and 10.00 g/kg of soil) and four WD cycles (0, 3, 6 and 9) were used to assess any changes in stability.

Dissolved organic matter (DOM) in sediment pore water is a complex molecular mixture reflecting various sources and biogeochemical processes. In order to constrain those sources and processes, molecular variations of pore water DOM in surface sediments from the NW Iberian shelf were analyzed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and compared to river and marine water column DOM. Weighted average molecular element ratios of oxygen to carbon ((O/C) wa ) and hydrogen to carbon ((H/C) wa ) provided general information about DOM sources. DOM in local rivers was more oxygenated ((O/C) wa 0.52) and contained less hydrogen ((H/C) wa 1.15) than marine pore water DOM (mean (O/C) wa 0.50, mean (H/C) wa 1.26). The relative abundance of specific compound groups, such as highly oxygenated aromatic compounds or nitrogen-bearing compounds with low H/C ratios, correspond to a high concentration of lignin phenols (160 lg/g sediment dry weight) and a high TOC/TN ratio (13.3) in the sedimentary organic matter and were therefore assigned to terrestrial sources. The lower degree of unsaturation and a higher relative abundance of nitrogen-bearing compounds in the pore water DOM reflected microbial activity within the sediment. One sampling site on the shelf with a high sediment accumulation, and a humic-rich river sample showed a wide range of sulfur compounds in the DOM, accompanied by a higher abundance of lipid biomarkers for sulfate-reducing bacteria, probably indicating early diagenetic sulfurization of organic matter.

Humeomics encompasses step-wise chemical fractionation and instrumental determination to fully characterize the heterogeneous molecular composition of natural organic matter. Humeomics applied to a terrestrial humic acid produced a recalcitrant end-residue, that was solubilized in alkali and size-fractionated by preparative high performance size exclusion chromatography (HPSEC). The ten separated size-fractions were then subjected to analytical HPSEC hyphenated with a high-resolution electrospray mass spectrometer (ESI-MS). Total ion chromatograms of size-fractions showed two eluting peaks, the molecular masses of which were identified with empirical formulae by ESI-MS. Most empirical formulae were easily associated with linear alkanoic, unsaturated, hydroxylated and hydroxy-unsaturated acids, as well as cyclic acids, but some compound structures were unclear. Tandem MS fragmentation was applied to one linear and three cyclic compounds, to elucidate their structures as hydroxyunsaturated hexanoic acid, two furane rings and a norbornane-like ring, respectively. The latter three compounds were never reported for terrestrial humic acid, but they resembled the carboxyl-rich alicyclic molecules, which had been proposed previously for dissolved organic matter. Quantitative measurement of components indicated that long-chain saturated acids were present in large-sized fractions more than in short-chain homologues, whereas unsaturated, hydroxylated and most cyclic acids were more abundant in small-sized fractions. This suggests that long, saturated and unsubstituted linear acids allow formation of large suprastructures, probably as a result of favorable intermolecular packing, compared with the irregularly shaped cyclic, unsaturated or hydroxylated compounds. We showed that humeomics clarifies the molecular composition and conformational arrangement of natural organic matter, and may help to elucidate the relationship between humic structure and environmental activity.

The complex nature of natural organic matter (NOM), and the impact of this matter on drinking water quality have necessitated the characterization studies of NOM. A fluorescence technique for the characterization of NOM in Malaysian river water is reported. Water samples from several river sampling sites were collected and concentrated using a low-pressure reverse osmosis (LPROM). Solid phase extraction (SPE) using C18 extraction cartridges were used to fractionate the water samples into humic and non-humic fractions. To differentiate and classify various types of humic substances, fluorescence was applied in emission, excitation and in synchronous-scan modes. A synchronous spectral profile was found to be able to differentiate humic and fulvic acids better than the emission or excitation spectra. Synchronous excitation spectra showed different spectral patterns for the water samples due to different origin. All water samples showed the presence of both fulvic and humic acids.

To understand the variations of organic carbon inputs in high latitude rivers, we tracked the changes in fatty acid concentrations and their stable carbon isotopic compositions in dissolved (DOM, <1 kDa), colloidal (COM, 1 kDa to 0.45 lm) and particulate (POM, >0.45 lm) organic matter collected from the upper Yukon River (Alaska, USA) during ice-open season from May to September 2002. In spite of the high variability in discharge, total organic carbon in the river continuously declined from the beginning of snowmelt, while fatty acid contents (normalized to organic carbon in each pool) varied independently in the three organic pools with the largest fraction of total fatty acids in the POM. Fatty acid compositions in each pool were similarly dominated by short-chain saturated (14:0, 16:0, and 18:0) and monounsaturated [16:1 and 18:1(nÀ9)] fatty acids (70–80%), while bacterial fatty acids [normal and branched 15:0 and 17:0 plus 18:1(n À 7)] comprised an important fraction (16–30% of the total) in all samples. The concentrations of individual fatty acids in the three pools varied greatly during the ice-open season, but the compound-specific stable carbon isotopic ratios of fatty acids in POM were less variable compared to those in DOM and COM. Mass balance calculation showed that land-derived fatty acids dominated in May (snowmelt) while aquatic produced fatty acids peaked in July, consistent with the maximum Chl-a concentration. In addition, bacteria-specific fatty acids (e.g., iso-15:0) had similar d 13 C ratios in all three pools, with little difference from those of bulk carbon. Our results suggest that relative inputs of organic matter from various sources into the upper Yukon River are significantly affected by snowmelt, rainfall, soil erosion, discharge, aquatic production, and biochemical degradation.

Water samples were collected in July 2001 from the Chena River in central Alaska. The natural organic matter (NOM) was size fractionated into particulate Full-size image (<1 K), colloidal Full-size image (<1 K)–Full-size image (<1 K) and dissolved Full-size image (<1 K) organic matter fractions, using filtration and ultrafiltration. The size-fractionated organic matter was then analyzed for organic carbon (OC) and nitrogen (N), isotopic Full-size image (<1 K) and Full-size image (<1 K)) and molecular composition, using continuous flow isotope ratio mass spectrometry and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Results of phase partitioning showed that, on average, about 6% of OC and 16% of N occurred in the form of POM while 66% of OC and 57% of N occurred in the form of COM, and 28% of the OC and 27% of the N were in the DOM form. Organic matter in the river water was found to be highly heterogeneous in terms of chemical composition and isotopic signatures. The C/N ratio was as low as 16±1 in the POM (n=2) to as high as 48±1 in the COM (n=3) and 38±4 in the DOM (n=3), suggesting a diagenetically younger POM. Values of Full-size image (<1 K) increased with decreasing size, varying from −29.59±0.45% in the POM to −27.47±0.06% in the COM to −16.93±0.08% in the DOM. In contrast, values of Full-size image (<1 K) decreased with decreasing size, from 2.64% in POM to 1.64% in COM to 1.33% in DOM. These results, together with radiocarbon measurements, suggest a preferential decomposition of lighter C isotope Full-size image (<1 K) and heavier N isotopic Full-size image (<1 K) from POM to COM to DOM. Results of py-GC/MS showed that the percentage of polysaccharides decreased with decreasing size, further supporting a degradation pathway of NOM from POM to COM and DOM in Chena River waters. More studies are needed to examine the seasonal and spatial variations of size-fractionated organic matter.

In many agricultural soils in the semi-arid and arid mediterranean climates, exposure to cyclic wetting and drying (WD) can reduce aggregate stability. The extent to which soil pretreatment with coal-derived humic substances (HS) can increase aggregate stability in soils exposed to cyclic wetting and drying (WD) was evaluated in this study. The soils studied are an Acireale silty clay loam from Sicily, a Principina silt loam from Tuscany and a Bovolone loam from Venetia in Italy. On each soil eight rates of the HS (0, 0.001, 0.01, 0.05, 0.10, 0.50, 1.00 and 10.00 g/kg of soil) and four WD cycles (0, 3, 6 and 9) were used to assess any changes in stability. On the Principina and Bovolone soils dominated by iUitic and smectic clay minerals, successive WD cycles reduced aggregate stability. On the Acireale soil, dominated by kaolinitic clay mineral, after initial decrease in stability following three WD cycles, the aggregates regained stability as cyclic WD continued. Amending the soils with low rates of HS (equivalent to 100-200 kg/ha) not only improved aggregate stability significantly (p-0.05) on all the three soils, but also reduced substantially the disaggregating effects of WD cycles. This work indicates that exogenous humic substances have a potential as soil conditioners in conservation practices aimed at increasing the structural stability of soils.

Natural organic matter (NOM) from two sites in South Australia were separated by Amicon YM and YC ultrafiltration (UF) membranes into five nominal fractions (o0.5, 0.5-3, 3-10, 10-30 and >30 kDa). These nominal fractions were then characterized for size and molecular weight (MW) distributions using flow field-flow fractionation. The results show that separation by UF did not produce fractions with the expected MW and size. Electrophoretic mobility measurements of the NOM fractions adsorbed to colloidal goethite showed no significant difference between the fractions. However solid-state 13 C NMR of the NOM fractions showed that the separation was influenced by molecular structure as well as molecular size. The results suggest that great caution needs to be exercised when interpreting molecular size and speciation results for humic substances obtained by membrane UF. r

Natural organic matter (NOM) is a very complicated mixture of organic compounds and is detected in all groundwater and surface waters. Besides NOM has a direct effect on health, it touches the performance of drinking water treatment processes (DWTPs) and so the safety of potable water. NOM may also disturb consumer satisfaction since it could participate in undesirable colors, tastes, and odors in potable water. This work aims to provide an insight into the effects of NOM on the global quality of drinking water, comprising its possible impacts on DWTPs and soon the safety of drinking water. It outlines the parameters that touch the level and property of NOM and examines the indexes to adopt when suggesting a NOM control strategy. Water source becomes highly polluted by organic compounds at a level that chemical oxygen demand is presently used to characterize surface water and biological treatment is suggested as a process for NOM removal in the DWTPs. Such behavior was not thinkable thirty years ago. The coagulation process remains importantly influenced by practical variables such as mixing conditions and pH control. Employing membrane processes instead of singular chemical oxidation and coagulation should be more promoted as water supplies become highly polluted in organic compounds.

The natural organic matter (NOM) present in water bodies is a complex mixture of organic
substances such as humic and fulvic acids, proteins, lipids, hydrocarbons and amino-acids. The
major fraction of the NOM occurs by degradation of plants and animals residual in terrestrial areas
and aquatic systems. The NOM is a direct problem in drinking water due to colour and taste.
Indirectly, NOM is a problem because it reacts with the most commonly used disinfectants,
chlorine, to form disinfection by-products some of which have been associated with an increased
risk of cancer. NOM can be define according to its biophysico-chemical functions and properties, as
humic (humic and fulvic acid) and non-humic substances (hydrophilic acids, carboxylic acids,
amino acids, carbohydrates, hydrocarbons). Humic substances (HSs) basically humic acids (HAs)
that are comprised of highly functionalized carbon rich polydisperse polyelectrolytes are the major
fraction of naturally occurring organic matters. Thus, the removal of HAs is an essential process.
This investigation was focused on develop of an innovative reactor and electrode configuration for
the removal of humic acid (HA). The fixed-bed electrocoagulation reactor comprised of aluminium
ball anode electrodes that placed in a cylindrical reactor. DOC and UV254 were taken in account for
reveal the removal efficiency of HA. The effect of initial pH (pHi), current density (j, mA/cm2),
operating time (min, t), and initial humic acid concentration (Co, mg/L) were investigated. The
result showed that the maximum DOC and UV254nm removal efficiencies were obtained at 4 of pH ,
6 mA/cm2 of current density and 30 mg/L of initial HA concentration as 90.76 and 95.66 %,
respectively.

Natural organic matter (NOM) is heterogenous mixture of organic compounds that enter the water from various decomposition and metabolic reactions, including animal, plant, domestic and industrial wastes. NOM refers to group of carbon-based compounds that are found in surface water and ground water. The aim of the study is to assess organic matter characteristics in Jagir River as drinking water source and to characterize the organic components that could be removed during coagulation. Coagulation is the common water treatment process can be used to remove NOM with FeCl3 coagulant in various dosage. NOM surrogates, including total organic carbon (TOC), ultraviolet absorbance at 254 nm (UV254) and specific UV absorbance (SUVA) were chosen to assess the organic removal. Results of jar test experiments showed that NOM can be removed about 40% of NOM surrogates with 200 mg/L FeCl3. About 60% removal of total organic fraction, which is mainly humic substances, as detected by size exclusion chromatography (SEC).

Natural organic matter (NOM) from two sites in South Australia were separated by Amicon YM and YC ultrafiltration (UF) membranes into five nominal fractions (o0.5, 0.5-3, 3-10, 10-30 and >30 kDa). These nominal fractions were then characterized for size and molecular weight (MW) distributions using flow field-flow fractionation. The results show that separation by UF did not produce fractions with the expected MW and size. Electrophoretic mobility measurements of the NOM fractions adsorbed to colloidal goethite showed no significant difference between the fractions. However solid-state 13 C NMR of the NOM fractions showed that the separation was influenced by molecular structure as well as molecular size. The results suggest that great caution needs to be exercised when interpreting molecular size and speciation results for humic substances obtained by membrane UF. r

Background: Filtration is a processing unit in a Drinking Water Treatment Plant (DWTP) that is used to remove particles from the water. This study is the result of pilot-scale research on Gravity Rapid Sand Filter (GRSF). The purpose of this paper was to evaluate the performance of the Triple Media Filter (TMF) (Granular Activated Carbon (GAC) + anthracite + garnet) and Dual-Media Filter (DMF) (anthracite + sand) in the removal of Natural Organic Matter (NOM) as a precursor of Trihalomethanes (THMs) and chlorination Disinfection by-Products (DBPs). Methods: Filtration rate was performed at conventional (120 m/d) and a high rate (240 m/d) and compared with full-sized Single Media Filter (SMF) with a sand media. The removal efficiency of turbidity, color, and UV absorption at a wavelength of 254 nm (UV 254) and Dissolved Organic Carbon (DOC) parameters were investigated. Besides, the Specific Ultraviolet Absorbance (SUVA) was calculated from the ratio of UV 254 to DOC. Results: The results showed that the Multimedia Filter (MMF) at 120 and 240 m/d filtration rate had higher removal efficiency compared with a control SMF in removing measured parameters (P<0.05). Also, similar filters have shown the same efficiency relative to each other in different loading rates and there was an insignificant difference. Conclusion: MMF can significantly remove organic pollutants and control the formation of DBPs during water treatment. The study suggests that SMF should be replaced with MMF to improve water quality.

Dissolved organic matter (DOM) in sediment pore water is a complex molecular mixture reflecting various sources and biogeochemical processes. In order to constrain those sources and processes, molecular variations of pore water DOM in surface sediments from the NW Iberian shelf were analyzed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and compared to river and marine water column DOM. Weighted average molecular element ratios of oxygen to carbon ((O/C) wa ) and hydrogen to carbon ((H/C) wa ) provided general information about DOM sources. DOM in local rivers was more oxygenated ((O/C) wa 0.52) and contained less hydrogen ((H/C) wa 1.15) than marine pore water DOM (mean (O/C) wa 0.50, mean (H/C) wa 1.26). The relative abundance of specific compound groups, such as highly oxygenated aromatic compounds or nitrogen-bearing compounds with low H/C ratios, correspond to a high concentration of lignin phenols (160 lg/g sediment dry weight) and a high TOC/TN ratio (13.3) in the sedimentary organic matter and were therefore assigned to terrestrial sources. The lower degree of unsaturation and a higher relative abundance of nitrogen-bearing compounds in the pore water DOM reflected microbial activity within the sediment. One sampling site on the shelf with a high sediment accumulation, and a humic-rich river sample showed a wide range of sulfur compounds in the DOM, accompanied by a higher abundance of lipid biomarkers for sulfate-reducing bacteria, probably indicating early diagenetic sulfurization of organic matter.

attributed to the entropy-driven tendency to exclude water molecules from humic association and thus decrease total molecular energy. This model of dissolved humic substances based on the reversible self-association of small molecules rather than on the macromolecular random coil represents a new understanding that should contribute to predict the environmental behavior of contaminants in association with natural organic matter.

Natural organic matter (NOM) refers to group of carbon-based compounds that are found in surface water and ground water. The aim of the study is to reveal organic matter characteristics in Jagir River as drinking water source and to characterize the organic components that could be removed by FeCl3 coagulation. Coagulation is the common water treatment process that can be used to remove NOM with FeCl3 coagulant in various dosage. NOM surrogates, including total organic carbon (TOC), ultra violet absorbance at 254 nm (UV254) and specific UV absorbance (SUVA) were chosen to assess the organic removal. Results of jartest experiments showed that NOM can be removed about 40% of NOM surrogates with 200 mg/L FeCl3. About 32% removal of dominated organic fractions humic substances from total fractions removal as detected by size exclusion chromatography (SEC)

The complex nature of natural organic matter (NOM), and the impact of this matter on drinking water quality have necessitated the characterization studies of NOM. A fluorescence technique for the characterization of NOM in Malaysian river water is reported. Water samples from several river sampling sites were collected and concentrated using a low-pressure reverse osmosis (LPROM). Solid phase extraction (SPE) using C 18 extraction cartridges were used to fractionate the water samples into humic and non-humic fractions. To differentiate and classify various types of humic substances, fluorescence was applied in emission, excitation and in synchronous-scan modes. A synchronous spectral profile was found to be able to differentiate humic and fulvic acids better than the emission or excitation spectra. Synchronous excitation spectra showed different spectral patterns for the water samples due to different origin. All water samples showed the presence of both fulvic and humic acids.

Discharge of wastewater into water body can change the quantity and quality of natural organic matter (NOM) in source water, because wastewater may contain dissolved effluent organic matter (dEfOM). dEfOM consists of a heterogenous mixture of organic compounds with various structures, such as dissolved organic matter, microbial by-products, endocrine disrupting compound, etc. The objectives of this study is to track the fate of dEfOM by using fluorescence excitation emission matrices (FEEMs) in order to apply of reclaimed water from industrial wastewater. Tracking of NOM was observed in industrial park of wastewater treatment, which is consist of equalization tank, coagulation, flocculation, sedimentation, activated sludge tank and clarifier tank. FEEMs with parallel factor analysis (PARAFAC) analysis decomposed the organic matter in wastewater into two components, namely component C1 at (Ex/Em): 330(235)/410 is humic acid like and fulvic, component C2 at (Ex/Em): 280(230)/350 is soluble microbial products and aromatic protein. Characteristic of dEfOM depends on the wastewater characteristic and its treatment processes.

Sediments exposed to simulated solar radiation release dissolved organic carbon (DOC). However, it is unclear how the provenance of sedimentary organic matter (OM) impacts this photorelease. In the first geographically extensive study of this kind, twenty three size fractionated fine grain sediments (< ca. 10 to 20 µm) from a variety of drainage basins were resuspended (at suspended solid loadings of 29 to 255 mg/l) and exhibited a net photochemical DOC release ranging from 2 to 178 µmol/g/h. There was a logarithmic increase of photoreleased DOC vs. the proportion of sedimentary organic carbon (%OC), most likely resulting from photon limitation at high sedimentary OC loading (i.e., high mass-specific absorption limiting light penetration). Sediment source and quality, as revealed by biomarkers, had a significant effect on DOC photorelease. The fatty acid terrestrial aquatic ratio (TARFA) indicated that terrestrially derived sediments exhibited relatively greater DOC photorelease. The long chain carbon preference index (CPI24-34) indicated that diagenetically unaltered terrestrial OM photoreleased more DOC than diagenetically altered terrestrial OM. The short chain carbon preference index (CPI14-22) demonstrated that sediments containing diagenetically altered planktonic or algal derived OM had a greater photorelease rate of DOC than fresh algal OM. This suggests that humic substances (humus and/or adsorbed humic and fulvic acids) play an important role in the photochemical dissolution of OC regardless of whether or not they are imported from upstream (i.e. terrestrial humics) or generated within the depositional or sedimentary environment (i.e. humification of algal dissolved OM).

In many agricultural soils in the semi-arid and arid mediterranean climates, exposure to cyclic wetting and drying (WD) can reduce aggregate stability. The extent to which soil pretreatment with coal-derived humic substances (HS) can increase aggregate stability in soils exposed to cyclic wetting and drying (WD) was evaluated in this study. The soils studied are an Acireale silty clay loam from Sicily, a Principina silt loam from Tuscany and a Bovolone loam from Venetia in Italy. On each soil eight rates of the HS (0, 0.001, 0.01, 0.05, 0.10, 0.50, 1.00 and 10.00 g/kg of soil) and four WD cycles (0, 3, 6 and 9) were used to assess any changes in stability. On the Principina and Bovolone soils dominated by iUitic and smectic clay minerals, successive WD cycles reduced aggregate stability. On the Acireale soil, dominated by kaolinitic clay mineral, after initial decrease in stability following three WD cycles, the aggregates regained stability as cyclic WD continued. Amending the soils with low rates of HS (equivalent to 100-200 kg/ha) not only improved aggregate stability significantly (p --0.05) on all the three soils, but also reduced substantially the disaggregating effects of WD cycles. This work indicates that exogenous humic substances have a potential as soil conditioners in conservation practices aimed at increasing the structural stability of soils.

Natural organic matter (NOM) refers to group of carbon-based compounds that are found in surface water and ground water. The aim of the study is to determine the efficiency of coagulation-filtration process for removing NOM by using fluorescence spectra analysis. NOM surrogates, including total organic carbon (TOC), ultra violet absorbance at 254 nm (UV254), specific UV absorbance (SUVA), and fluorescence spectra analysis with Fluorescence integration method were chosen to assess the organic matter removal. Experiment was conducted by using activated carbon or silica sand as filter media under various flow rate after FeCl3 coagulation. Results revealed that activated carbon filter under lower flow rate rate showed better removal efficiency of NOM surrogates, around 40-60% and all fluorescence component, less than 40%, especially humic acid-like than silica filter media.