Taha F. Marhaba

USING PRINCIPAL COMPONENT ANALYSIS TO MONITOR SPATIAL AND TEMPORAL CHANGES IN WATER QUALITY

Chemical, biological and physical data monitored at 12 locations along the Passaic River, New Jersey, during the year 1998 are analyzed. Principal component analysis (PCA) was used: (i) to extract the factors associated with the hydrochemistry variability; (ii) to obtain the spatial and temporal changes in the water quality. Solute content, temperature, nutrients and organics were the main patterns extracted. The spatial analysis isolated two stations showing a possible point or non-point source of pollution. This study shows the importance of environmental monitoring associated with simple but powerful statistics to better understand a complex water system.

The variation of mass and disinfection by-product formation potential of dissolved organic matter fractions along a conventional surface water treatment plant

Dissolved organic matter (DOM) influences many aspects of water treatment, including the formation of potentially harmful disinfection by-products (DBPs) when disinfectants are applied. DOM from a conventional surface water treatment plant (WTP) in Northern New Jersey was isolated and fractionated using resin adsorption chromatography into six different fractions. These fractions are operationally categorized as hydrophobic acid, hydrophobic neutral, hydrophobic base, hydrophilic acid, hydrophilic neutral and hydrophilic base. The hydrophilic acid fraction was found to be the most abundant fraction in the source water. The hydrophilic neutral, hydrophilic acid and hydrophobic acid fractions had the highest removal efficiency through the WTP (about 65%). The variation and removal effectiveness of each fraction along the WTP was studied. Seven-day chlorine DBP formation potential (FP) tests were performed on all DOM fractions through the WTP. For the source water studied, the hydrophilic acid fraction was found to be the most reactive precursor to the trihalomethane (THM) formation. The hydrophobic neutral fraction was found to be the fraction of concern with respect to the FP of haloacetic acids (HAAs) class of DBPs. The FP of each fractions class of DBPs was found to be amenable for reduction along the treatment train, specifically by coagulation/sedimentation. The fractionated approach concept showed to be very beneficial in the study of DBP precursors and their effective removal by physical and chemical treatment.

Modified dissolved organic matter fractionation technique for natural water

A technique to fractionate dissolved organic materials (DOMs) from low DOM water (<5mg/l) was developed by using triple columns of DAX-8 adsorption resin, one column of AG-MP-50 cationic resin, and another column of WA 10 weak anionic resin in sequence. The procedure was then applied to fractionate water samples obtained at various sampling locations throughout two surface water treatment plants (WTPs) in central New Jersey to study its effectiveness, DOM occurrence, and variation along treatment units. The treatment plants utilize different treatment methods, hence producing variability in DOM fractions suitable for examining the procedures effectiveness. This procedure was compared with current fractionation protocols and proved to be accurate in fractionation of low DOM water.

Rapid identification of dissolved organic matter fractions in water by spectral fluorescent signatures

Total organic carbon (TOC) analysis has been typically used as an aggregate measure of natural organic matter (NOM) in water. NOM from New Jersey surface water sources were isolated and fractionated by resin adsorption techniques into hydrophobic acid, hydrophobic neutral, hydrophobic base, hydrophilic acid, hydrophilic neutral and hydrophilic base. The Spectral Fluorescent Signatures (SFS) technique through a database of spectral characteristics specific to each fraction was developed for the identification of the six dissolved organic carbon (DOM) fractions. Among the main advantages of the technique are high sensitivity and rapid identification. The potential use of the technique for the rapid qualitative and quantitative identification of the DOM fractions for source water assessment and water treatment process optimization is presented.

Changes in NOM Fractionation through Treatment: A Comparison of Ozonation and Chlorination.

Abstract NOM isolation and fractionation to provide insight into the effectiveness of ozonation vs. conventional water treatment was done. In this research, the dissolved portion of natural organic matter (NOM) or dissolved organic matter (DOM) at two surface drinking water treatment plants that treat the same source water was fractionated by resin adsorption. The first treatment plant uses conventional treatment (coagulation, sedimentation, and filtration) with intermediate free chlorination and post chlorination while the second plant uses conventional treatment with pre and intermediate ozonation, and multi-media filtration unit operation. Several different sampling locations within each plant were selected for DOM isolation and fractionation into six fractions (hydrophobic acid, neutral and base, and hydrophilic acid, neutral, and base). The effectiveness of each treatment plant on the oxidation and removal of each organic fraction are discussed. Oxidation by ozone leads to better overall performance in the removal of DOM.

Rapid delineation of humic and non-humic organic matter fractions in water.

Dissolved organic matter (DOM) in water is often characterized by aggregate parameters like dissolved organic carbon (DOC). DOM from conventional surface water treatment plant in Northern New Jersey was isolated and fractionated using resin adsorption chromatography into six different fractions, which were operationally categorized as hydrophobic acid, hydrophobic neutral, hydrophobic base, hydrophilic acid, hydrophilic neutral and hydrophilic base. The spectral fluorescent signatures (SFS) technique was developed for the quantitative identification of the six fractions by post-processing analysis that includes a statistical model. The SFS is the total sum of emission spectra of a sample at different excitation wavelengths, recorded as a matrix of fluorescent intensity in coordinates of excitation and emission wavelengths, in a definite spectral window. High sensitivity and rapid identification and quantification of DOM fractions are among the main features of the technique. Since hydrophobic and hydrophilic substances are considered more humic and non-humid in nature, respectively, the technique provided an opportunity to rapidly delineate source waters in terms of such categories.

Ceramic membrane defouling (cleaning) by air Nano Bubbles.

Ceramic membranes are among the most promising technologies for membrane applications, owing to their excellent resistance to mechanical, chemical, and thermal stresses. However, membrane fouling is still an issue that hampers the applications at large scales. Air Nano Bubbles (NBs), due to high mass transfer efficiency, could potentially prevent fouling of ceramic membrane filtration processes. In this study, bench and pilot scale ceramic membrane filtration was performed with air NBs to resist fouling. To simulate fouling, humic acid, as an organic foulant, was applied to the membrane flat sheet surface. Complete membrane clogging was achieved in less than 6 h. Membrane defouling (cleaning) was performed by directly feeding of air NBs to the membrane cells. The surface of the ceramic membrane was superbly cleaned by air NBs, as revealed by atomic force microscope (AFM) images before and after the treatment. The permeate flux recovered to its initial level (e.g., 26.7 × 10(-9) m(3)/m(2)/s at applied pressure of 275.8 kPa), which indicated that NBs successfully unclogged the pores of the membrane. The integrated ceramic membrane and air NBs system holds potential as an innovative sustainable technology.

Interaction Between Organic Species in the Formation of Haloacetic Acids Following Disinfection

The formation of haloacetic acids (HAAs) from the chlorination of individual and binary mixtures of organic fractions obtained from the intake of Bangkhen Water Treatment Plant in Bangkok, Thailand was investigated. Experimental results revealed that, as an individual fraction, hydrophobic base (HPOB) was the most active in forming HAAs (approx. 200 microg/mg) whereas hydrophilic acid (HPIA) was the least (approx. 40 microg/mg). In binary mixtures, acid fractions exhibited stronger inhibitory effect in forming HAAs than base fractions. With the set of experimental data obtained from this work, no relationships between specific HAA formation potential and various organic fractions concentrations in binary mixtures could be formulated. Among the various individual HAA species obtained from the chlorination of each individual organic fraction, dichloroacetic acid (DCAA) was found to be predominant. On the other hand, the chlorination of binary organic fraction mixtures often led to the formation of monochloroacetic acid (MCAA) as the predominant HAA species.

Principal component regression model applied to dimensionally reduced spectral fluorescent signature for the determination of organic character and THM formation potential of source water.

The characterization of dissolved organic matter (DOM) in source water not only is central to the study of precursors to disinfection by-products (DBPs), but can also aid in controlling the discharge of potentially harmful organic chemicals in water bodies. Rapid determination of six DOM fraction concentrations provides an added advantage in understanding the organic character of water in comparison to the measure of dissolved organic carbon (DOC), which is an aggregate parameter typically used by water purveyors. The experimental procedure for DOM isolation and fractionation by ionic resins is lengthy and tedious. Many attempts have been made towards the development of faster and reliable techniques including statistical analysis applied to spectral fluorescent signature (SFS). Fluorescence is a very sensitive technique and works best only at certain wavelengths that are different for different materials. It is therefore difficult to quantify a material using fluorescence technique, especially when the entire fluorescence matrix is considered. To address this difficulty, an innovative two-stage processing technique is developed in this research in order to build an enhanced, more robust empirical model. At stage I, the dimensionality of the input data is reduced by focusing on specific portion of the entire matrix obtained by applying scatter removal, peak analysis, and coefficient of variation (CV) analysis. Then statistical analysis in the form of principal component regression (PCR) follows as stage II. In addition, the same technique is applied to predict trihalomethanes formation potential (THMFP). This model provides better sensitivity and accuracy, while maintaining the advantages of the SFS technique for rapid identification and quantification of DOM fractions.

Kinetics of trihalomethane formation from organic contaminants in raw water from the bangkhen water treatment plant

The fractionation of raw water from Bangkhen water treatment plant, Bangkok, Thailand revealed that the mass distribution sequence of the six organic fractions from high to low was hydrophilic neutral (HPIN), hydrophobic acid (HPOA), hydrophilic acid, hydrophobic neutral, hydrophilic base, and hydrophobic base. The main organic matter components in raw water were HPIN and HPOA, which were also the two most important contributors of trihalomethane formation potential (THMFP). Linear dependencies between the level of each organic fraction and the formation potential of THM species were observed, which suggested the reactions between the organic fraction and chlorine during the chlorination were first order. The fractionation led to a deviation of bromide concentration in each organic fraction from the original concentration, and this affected the formation of brominated THM species. However, this effect was demonstrated to be within an acceptable range. The chlorination of an individual organic fraction resulted in a higher level of THMFP than that of the raw water and mixed fractions, indicating an inhibitory effect between the organic species. *Presented at “The 2nd Asian International Conference on Ecotoxicology and Environmental Safety” (SECOTOX 2004), Songkla, Thailand, 26–29 September 2004.