Ivana Ivančev-Tumbas

Removal of arsenic and natural organic matter from groundwater using ferric and alum salts: A case study of central Banat region (Serbia)

This paper presents a comparison of the efficacy of three different coagulants (polyaluminium chloride (PACl), Aluminium sulphate (Al2(SO4)3) and ferrous chloride (FeCl3)) for natural organic matter and arsenic (As) removal from groundwater. Coagulation efficacy was evaluated for the coagulants alone and for combinations of them (PACl/FeCl3; Al2(SO4)3/FeCl3), on the basis of changes in dissolved organic matter (DOC) and arsenic content. For single coagulants, PACl (30 mg Al/L) showed optimal efficacy for DOC removal (57%, relative to raw water). The highest arsenic reduction (< 5 μ g As/L in coagulated water) was achieved when a very high 300 mg/L dose of FeCl3 was used. However, if PACl (30 mg Al/L) and FeCl3 (10 mg FeCl3/L) are combined, the efficacy of DOC removal increases compared to PACl and FeCl3 alone under similar doses (66% decrease in DOC relative to raw water). The DOC and As contents of the coagulated water after application of these doses were 2.26 mg C/L and 9.7 μ g/L, respectively, compared to 6.44 mg C/L and 60.5 μ g As/L measured in the raw groundwater. The combination of Al2(SO4)3 and FeCl3 did not show any improvement in DOC and As removal efficacy relative to using those coagulants alone.

The relationship between whole effluent toxicity (WET) and chemical-based effluent quality assessment in Vojvodina (Serbia)

The relationship between whole effluent toxicity (WET) and chemical-based effluent quality assessment across a range of effluent types was examined for the first time in Serbia. WET was determined by Daphnia magna acute tests, while chemical-based toxicity was taken as theoretical for concentrations of priority chemicals and effluent quality assessment based on the valid Serbian regulations. A poor correlation was found between WET and chemical-based effluent quality assessment: positive toxicity tests were found, in general, in cases where samples satisfied the requirements of mandatory effluent monitoring. Statistically insignificant correlation between the predicted and observed toxicity indicated that the presence of priority substances accounted to the overall toxicity only to a certain degree, most probably due to a rather short list of priority pollutants regularly analysed in effluents. Current monitoring requirements neglect hazards that derive from potentially present toxicants and unpredictable toxicity of complex mixtures, which led to poor correlation between the WET and chemical-based results in this study.

Effects of coagulation processes on aldehydes formation in groundwater treated with common oxidative agents.

This work is concerned with the effects of coagulation processes with two different coagulants (polyaluminum chloride (PACl) and Al2(SO4)3) on aldehydes formation during oxidation with common oxidants (ozone, chlorine and chlorine dioxide) in a particular groundwater source in Northern Banat region, Yugoslavia. Aldehydes concentrations in coagulated water were lower than in raw water. In contrast, obtained results showed that specific contents of these disinfection byproducts (microg mg(-1) TOC) showed an increase after coagulation processes in a number of samples. Results indicate that the choice of the coagulant-oxidant combination may be important as well as the type of filtration bed, retention time, and filter washing regime in the removal of aldehydes from water.

The fate and importance of organics in drinking water treatment: a review

In the pioneer days, the main driving forces for research of organics in drinking water treatment (DWT) were human health risks and optimisation of technology. The focus was on natural organic matter (NOM) structure, disinfection by-products (DBPs) formation, NOM removal by means of coagulation, adsorption, and oxidation, and development of the most efficient water treatment trains. Surprisingly, after decades of research, rapid development of analytical techniques and progress in risk assessment, the same driving forces are still in the limelight — although the topics have changed slightly. The attention switched from trihalomethanes to a new generation of DBPs. The definition of hydrophilic/hydrophobic NOM depends on the technique used for characterisation. It has become evident that numerous organic compounds can threaten water supply sources. Some of them had been ignored or overlooked in the past, but have recently been detected by advanced analytical tools even in drinking water. Prioritisation becomes priority per se. As far as processes are concerned, mainstream research has been following three lines: fouling mechanisms, application of hybrid processes and interactions between synthetic organic chemicals, other water constituents and materials used in DWT. Significant development has been made in membrane technology. This paper presents a broad overview of the recent organics research. Although the state-of-the-art technologies seem to have an answer to each and every question raised, it is still necessary to deal with specific problems on a case-by-case basis mainly due to the unique nature of NOM and different xenobiotics that may appear in various types of waters. In the end, human health risk, which derives from the presence/absence of organics, is only the tip of the iceberg — underneath lies a whole new universe — the socio-economic aspect of water treatment and quality that deserves much more attention.

Removal of Natural Organic Matter from Groundwater Using Advanced Oxidation Processes at a Pilot Scale Drinking Water Treatment Plant in the Central Banat Region (Serbia)

To improve water quality, a pilot-scale evaluation into upgrading the conventional treatment process was conducted. By following DOC content, UV254 absorbance, SUVA and by-products formation, three oxidative pre-treatments were evaluated: pre-ozonation (2.2 g O3/m3); O3/H2O2 process (2.2 g O3/m3; H2O2:O3 = 1:2) and O3/H2O2 process (2.2 g O3/m3; H2O2:O3 = 2:1). The second pre-treatment gave the best results, with a final average DOC content of 0.9 mg C/L, UV254 absorbance of 0.06 cm−1 and the lowest THMFP of 130 μg/L. UV254 absorbance can serve as a proper indicator for predicting THM and HAA formation, yielding a correlation coefficient ≥ 0.90.

Sorption of atrazine, alachlor and trifluralin from water onto different geosorbents

The sorption behavior of the herbicides atrazine, alachlor and trifluralin on four sorbents (two modified organoclays, one model sediment, and one natural sediment) in three water matrices (synthetic water, natural groundwater and surface water) was investigated. The influence of the sorbent and water matrix characteristics was elucidated. All adsorption isotherms fitted well with the Freundlich model. Based on the Kd values, the organically modified bentonite and model sediment proved to be the most effective sorbents for the investigated herbicides. A linear correlation of Kd with the total organic carbon (TOC) concentration was found for trifluralin in the synthetic water matrix (c0 = 0.01 mg L−1). In the case of higher trifluralin concentration and for other tested herbicides at all concentrations the influence of both the sorbent organic matter quality and possible interactions with the mineral phase was indicated. Furthermore, the results showed different influence of the type and the content of dissolved organic carbon (DOC) in the water phase on the sorption of all the herbicides, depending on the herbicide concentration and the sorbent applied. It was confirmed that the comparison of sorbent efficiency should be done in native matrix since sorption coefficients vary depending on pollutant concentration, DOC concentration and DOC fraction. This finding is considered to be important for remediation of contaminated sites.

Case Study of Petroleum Contaminated Area of Novi Sad After NATO Bombing in Yugoslavia

The 1999 NATO bombing of the oil refinery in Novi Sad (Yugoslavia) has heavily contaminated the Danube River and its sediments, as well as the surrounding soil and groundwater. The destruction of the factories released 73,569 tons of crude oil of which 90% was incinerated, 560 tons reached the Danube River, and the remainder was spilled onto the soil. The contents of oil and oil derivatives in the soil were in the range of 3 to 42,000 mg/kg. The first soil layer contained an average of 67,000 mg/kg of crude oil and oil derivatives. The layers beneath it, above the groundwater table, contained 56 ml/l of free oil derivatives in the drained water. The spreading of this pollution could imperil the groundwater quality in the water supply zone because the refinery is located in the hinterland of the zone. The quality of water and sediment samples was monitored from April 1999 to November 2000 by measuring concentrations of hydrocarbons and polyaromatic hydrocarbons (PAH). The hydrocarbon content in the Danube River water in October 2000 was about 20% of the value measured at the time of the accident. Immediately after the accident the concentration of mineral oil in the surface sediment was in the range of 0.11 to 0.29 g/kg. At the same time PAH concentrations in the river sediment were up to 160 mg/kg, depending on the sampling site location. The values showed a decrease in the course of further monitoring.

Toxicological and chemical investigation of untreated municipal wastewater: Fraction- and species-specific toxicity

Absence of a municipal wastewater (WW) treatment plant results in the untreated WW discharge into the recipient. The present study investigated toxic effects and chemical composition of water extracts and fractions from untreated WW and recipient Danube River (DR). Samples were prepared by solid-phase extraction and silica gel fractionation and screened for EROD activity and cytotoxicity using aquatic models, comprising of fish liver cells (PLHC-1) and a model of the early development of zebrafish embryos, while rat (H4IIE) and human (HepG2) hepatoma cells served as mammalian models. Polar fraction caused cytotoxicity and increased the EROD activity in PLHC-1 cells, and increased mortality and developmental abnormalities in developing zebrafish embryos. In H4IIE, polar fraction induced inhibition of cell growth and increased EROD activity, whereas HepG2 exerted low or no response to the exposure. Non-polar and medium-polar fractions were ineffective. Tentative identification by GC/MS showed that WW is characterized by the hydrocarbons, alkylphenols, plasticizers, and a certain number of benzene derivatives and organic acids. In DR, smaller number of organic compounds was identified and toxicity was less pronounced than in WW treatments. The present study revealed the potent toxic effect of polar fraction of untreated WW, with biological responses varying in sensitivity across organisms. Obtained results confirmed that fraction- and species-specific toxicity should be considered when assessing health risk of environmental pollution.

Toxicological profiles assessment of the water and sediments from the Krivaja and Jegrička Rivers, Serbia

This study utilizes a combinatorial bio/chemical approach to assess the toxicological profiles of organic pollutants in water and sediment samples from two watercourses that are under significant anthropogenic pressure—the Krivaja and Jegrička rivers in Serbia. Sample preparation by solid-phase extraction and silica-gel fractionation followed by GC/MS analysis, allowed the tentative identification of a variety of non-target contaminants, divided into non-polar, medium-polar and polar fractions. The instrumental analysis revealed slightly different toxicological profiles for the water and sediment from both rivers, and confirmed the presence of various classes of organic contaminants, from non-polar hydrocarbons, to more polar compounds such as aldehydes, ketones and phenols. Polycyclic aromatic hydrocarbons and pesticides were identified, but below toxicologically relevant concentrations. The results of bioanalyses on H4IIE and PLHC-1 cells indicated that cytotoxic potential was pronounced in Jegrička water and sediment samples, and CYP1A inducing potential was observed in both Krivaja and Jegrička sediment samples, although they did not reflect high levels of contamination. Based on the overall data, the sediments of the Krivaja and Jegrička rivers are a more toxicologically relevant matrix than the water.

Effects of O3, O3/H2O2 and Coagulation on Natural Organic Matter and Arsenic Removal from Typical Northern Serbia Source Water

The objectives of this study were to investigate the effects of ozone and the O3/H2O2 process on FeCl3 coagulation efficiency for the removal of the high content of natural organic matter (NOM) and arsenic (As) from groundwater (DOC = 9.27 ± 0.92 mg/L; 51.7 ± 16.4 µg As/L). Arsenic and NOM removal mechanisms during coagulation/flocculation are well investigated. However, data concerning arsenic removal in the presence of NOM, which is the subject of this article, are still insufficient. Laboratory and pilot plant test results have shown that the competition of NOM and As for adsorption sites on the coagulant surface have great influence on coagulation/flocculation efficiency for their removal. With both oxidation pre-treatments, arsenic content after the coagulation process was less than 2.0 µg/L in treated water. Application of ozone has a lower influence on coagulation efficacy in terms of DOC reduction, compared to the O3/H2O2 process with the same ozone dose.