Mile Klašnja

Removal of water turbidity by natural coagulants obtained from chestnut and acorn

The ability of seed extracts of several species of chestnut and acorn to act as natural coagulants was tested using a synthetic turbid water. Active components were extracted from ground seeds of Horse chestnut and acorns of some species of family Fagaceae: Common oak, Turkey oak, Northern red oak and European chestnut. All investigated extracts had coagulation capabilities and their amounts depended on pH values and initial turbidities. The seed extracts from European chestnut and Common oak acorn were the most efficient expressing the highest coagulation activities, about 80% and 70%, respectively, in both low and medium investigated water turbidities at the lowest coagulant dose 0.5 ml/L.

Modified hardwood sawdust as adsorbent of heavy metal ions from water

The sawdust of oak and black locust hardwood was found to have good adsorption capacities for heavy metal ions. The leaching of coloured organic matters during the adsorption can be prevented by each of the following pre-treatments of adsorbents: with formaldehyde in acidic medium, with sodium hydroxide solution after formaldehyde treatment, or with sodium hydroxide only. The studies indicated that the leaching of coloured matters from modified hardwood sawdust was less than that from unmodified hardwood sawdust, namely between 70 and 94%, dependent on wood species and the method of modification. At the same time, adsorption capacities of modified adsorbents were higher than unmodified adsorbents when sodium hydroxide was applied for modification. When formaldehyde was applied for modification, the adsorption capacities of adsorbents remained unchanged. Only the application of sodium hydroxide was recommended for modification of hardwood sawdust.

A comparative study of the effects of ozonation and TiO2-catalyzed ozonation on the selected chlorine disinfection by-product precursor content and structure

This study compares the effects of ozonation (0.4-3.0 mg O(3)/mg DOC) and TiO(2)-catalyzed ozonation - TiO(2)-O(3) (0.4-3.0 mgO(3)/mg DOC; 1.0 mgTiO(2)/L) at pH 6 on the content and structure of natural organic matter (NOM) and trihalometane (THM) and haloacetonitrile (HAN) precursors in groundwater. The investigated groundwater from Northern Serbia is rich in NOM (9.85 mg/L DOC) which is mostly of hydrophobic character (65% fulvic acid and 14% humic acid fraction). It was found that the TiO(2)-catalyzed process, by favoring the radical mechanism of NOM oxidation, resulted in a more effective reduction in the content of total NOM (up to 18% DOC) compared to ozonation alone (up to 6% DOC). The use of TiO(2) also resulted in an improvement of ozonation in terms of THM precursor content removal (up to 80%). On the other hand, the application of both oxidation treatments resulted in an increase in the HANFP compared to the raw water. NOM oxidation during ozonation and TiO(2)-O(3) caused changes in their structure in the direction of an increased proportion of the hydrophilic fraction (up to 70%), which has the most reactive THM and HAN precursors, as well as the fraction with the highest content of their brominated species.

Study of the Adsorption of Copper(II) Ions from Water onto Wood Sawdust, Pulp and Lignin

The adsorption of copper(II) ions from aqueous solution onto sawdusts from different kinds of wood, pulp and Kraft lignin has been studied. The results of batch studies showed that Kraft lignin was a good adsorbent over the whole concentration range studied, hard woods (oak and black locust) were good when the Cu(II) ion concentration in the aqueous solution was high, while soft woods (poplar, willow, fir) and pulp were good for the adsorption of Cu(II) ions when the latter were present over the low concentration range. The maximum adsorption capacities of the adsorbents investigated towards Cu(II) ions were in the 1.77–9.35 mg/g range. Isotherms were used to obtain the corresponding thermodynamic parameters. Almost complete Cu(II) ion desorption was achieved using 0.1 M mineral acid solutions. The regenerated adsorbents could be used in several adsorption/desorption cycles.

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.

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.

Tracking disinfection by-products and arsenic removal during various drinking water treatment trains

In the central Banat region (Northern Serbia), groundwater is used as a drinking water source. Raw water originates from a 40-80 m and 100-150 m deep layer. It contains a high amount of natural organic matter (DOC = 9.17+/-0.87 mg C/L) with a trihalomethanes formation potential of 448+/-88.2 microg/L and a haloacetic acid formation potential of 174+/-68.9 microg/L. A high amount of arsenic (86.0+/-3.4 microg/L) is also found in this water. This study used a pilot-scale system to investigate the possibilities of combining polyaluminium chloride and ferrous-chloride to remove disinfection by-products precursors and arsenic by coagulation. Two treatment trains with different pre-treatment steps were investigated (ozone vs. H2O2/O3). For the final water polishing, filtration with granulated activated carbon (GAC) was applied. Both investigated treatment lines achieved a satisfactory chemical water quality. Simulation of disinfection conditions was performed and the contents of trihalomethanes and haloacetic acids measured, to investigate whether the chemical quality of the water remained satisfactory over a 48 hour period.

Improving the Electrokinetic Remediation of Nickel-, Cadmium-, and Lead-contaminated Sediment

In this work, the simultaneous application of bipolar electrodes and a longer cathodic compartment length without agents addition was used as an enhanced electrokinetic treatment of Ni-, Cd-, and Pb-contaminated sediment. Conventional and enhanced treatments were investigated and their efficacy assessed by comparing the residual metals content in the sediment with values given by Dutch standards. After conventional treatment removals of 20%, 19%, and 31% for Ni, Cd, and Pb were achieved, whereas the enhanced treatment achieved removal efficacies of 36% for Ni, 42% for Cd, and 43% for Pb. Results indicate that the simultaneous application of the techniques mentioned is effective for removing Ni and Pb whereas Cd was not removed to the desired level. Here we show that the addition of chemicals is not necessary to increase the efficacies of electrokinetic sediment treatments, so the simultaneous application of the techniques mentioned can be described as environmentally friendly.

Characterization of raw and treated sugar beet shreds for copper ions adsorption

AbstractLignocellulosic materials have a great potential to be converted into different high value products including biofuels, value-added chemicals, and cheap energy sources for microbial fermentation and enzyme production. Their multifunctionality and ability to reuse contribute to their great importance in terms of environmental protection and sustainable development. Such materials are sugar beet shreds (SBS) which are usually used as animal feed but since they are produced in large amount in sugar industry, they can also be used as an adsorbent or for bioethanol production. Bioethanol production from SBS includes pretreatment processes in order to remove pectic substances and lignin, followed by enzymatic hydrolysis of cellulose in order to obtain the solution of fermented sugars. A novelty in this work is the investigation if solid residues from the pretreatment process of SBS for bioethanol production can be used as adsorbents, the same as raw SBS. Textural characteristics and capacities for coppe...