Due to very high concentration of organic matter there is a great need for alternative solutions for drinking water disinfection in the world. Chlorine dioxide has been successfully used for almost 50 years for disinfection and later for taste removal, odor control, color reduction and oxidation of inorganic compounds such as iron and manganese. An advantage of using chlorine dioxide instead of chlorine is that it does not directly react with organic matter and form halogenated byproducts when it is used for disinfection. THMs, such as CHBr3, ChCl3 etc, are considered as most dangerous for people health. In this article we are to represent the results got from raw water disinfection treatment with chlorine dioxide.

The paper presents the results of laboratory research and application of continuous electro-coagulation and electro-flotation (ECEF) to remove natural organic matter (NOM) from groundwater in the treatment of drinking water. The highest NOM removal efficiency for current density of 5.78 mA/ cm square according to UV254 absorbance and dissolved organic matter (DOC) was 77% and 71% respectively. The specific energy and aluminum electrode consumption was 2.01 kWh/cubic m, 80 g Al/cubic m, respectively.

This paper presents the data of sediment quality in the zone of three sources for water supply in Novi Sad, Serbia. The data indicate that the sediment in the area of these sources contain petroleum products (mineral oils) above the permissible concentrations. Only in one sample of sediment was detected DDT / DDD / DDE in the location of the source against the Strand wells RB-1 in a concentration which can specify as the maximum risk. The data indicate a significant anthropogenic influence of refinery waste water and urban waste water, motor boats in the marine (source Strand) and anchor of ships (source Petrovaradinska Ada) on the quality of sediment in these sources.

Quality of groundwater from aquifers used for water supply in the town of Zrenjanin, does not meet the drinking water quality requirements. Among the basic problems are the high content of natural organic matter and arsenic, but also sodium and boron. This paper presents one of possible alternative of technological solutions for drinking water preparation in Zrenjanin. Research has lasted three years. The paper presents a only an outline of the drinking water preparation processes.

Arsenic speciation can be very important in analysis of water, foodstuffs, and environmental samples, besides of total arsenic analysis. Hydride generation atomic absorption spectrometry can be used for speciation analysis based on different hydride generation condition. In our work, we studied effect of L-ascorbic acid like the reaction medium and the prereducing agent.

In the 21 century drinking water of acceptable quality should be available to every person. Numerous investigations are on-going worldwide around the world, to develop innovative and cost attractive approaches for production of high quality drinking water. To allow application of new treatment technology in practice, pilot testing under field conditions are required. Groundwater used for drinking water productions in the Subotica municipalities (Serbia) contains elevated concentrations of arsenic, iron and ammonia, and therefore provided a good basis for continuation of research of UNESCO-IHE, the Netherlands Institute for Water Education, that has been developing innovative water treatment technologies specifically in the field of groundwater treatment and specifically arsenic removal. Objective of this project presented in this paper were to test under field conditions IHE ADART, the innovative adsorptive arsenic removal technology. The pilot project has demonstrated that in addition to conventional approach based on coagulation and break-point chlorination, there is and alternative treatment approach based on biological ammonia removal and adsorptive removal of arsenic that could be economically and ecologically attractive.

The city of Novi Sad uses groundwater as drinking water source. For this purpose only water from Danube alluvium is used, and the water is abstracted at three sites. The Danube water and sediment quality in the zone of the drinking water sources is of great importance, as the river Danube recharge alluvial aquifer. The microbiological quality of these environments was monitored, in order to determine their influence on drinking water quality. The water characterization was carried out using sanitary and ecological microbiological parameters of Danube water and sediment.

This study was performed to investigate the efficiency of Fenton's process (FP) for removing natural organic matter, in particular the main disinfection by-products precursors. In order to determine the optimal reaction conditions of the process, the influence of pH, mixing speed and reaction time were investigated, as well as the influence of initial concentration and the molar ratio of Fe2+ and H2O2. The best results in terms of reducing the DOC content (by 82%) were achieved under pH 5, 30 rpm, reaction time of 15 min, Fe2+ concentration of 0.25 mM and a molar ratio of 1:10, and in terms of reducing trihalomethane and haloacetic acid precursors (by 98-99%) under a Fe2+ and H2O2 molar ratio of 1:20.

Coagulation and flocculation can be efficiency applied in drinkling water treatment, in order to remove natural organic matter (NOM). However, in the experiments presented in this paper, the water used is very rich in NOM, and required investigations of additional processes. In order to increase the efficiency of coagulation and flocculation processes in removing NOM from groundwater, the following processes were investigated: adsorption on powdered activated carbon (5-30 mg PAC/l) and preozonation with applied ozone doses of 1.1-6.3 mg O3/l. The parameters used to evaluated the changes in NOM content during the experiment were: KMnO4 consumption, UV absorbance at 254 nm, pH and turbidity.

There was carried out microbiological analysis of five bottled water of manufacturers from Serbia. Bacteriological quality was estimated using important parameter-aerobic mesophylic bacteria. Two nutrient media were used: standard (PCA) and low nutrient R2A. Plates were incubated at two temperatures (37 deg C and 22 deg C) during 24 hours, 48 hours, 3 days and 5 days. Results show that this group of bacteria is very abudant in bottled waters and their number depends on water types and manufacturers. Moreover, water from different bottles of the same manufacturer has different microbiological quality. Used media, temperatures and period of incubation also have influence on results and R2A medium gives higher values of aerobic mesophylic bacteria.