The paper presents results of microbiological quality of three drinking water sources – Ratno ostrvo, Petrovaradinska ada and Strand. The following analyses were carried out in 2010: total count of aerobic mesophilic bacteria at 37 deg C, count of organotrophs (categorization according to Kohl), aerobic facultative organotrophs, lipolytic and hydrocarbon oxidizing bacteria. Organotrophic count was determined on low nutritive R2A medium. Enzymatic activity of water was also determined and water was categorized according to index of phosphatase activity (IFA).

This study was performed to investigate the influence of the ozonation process on natural organic matter (NOM) and trihalomethane, haloacetonitrile and chloropicrin precursors in groundwater. The largest reduction in dissolved organic carbon, DOC (up to 25%) and UV 254 values (up to 69%) was achieved using 3 mg O3/mg DOC. Reducing the total organic matter resulted in a reduction of trihalomethanes precursors to 194 micro g/L. On the other hand, when it comes to the precursors of the high priority nitrogenous disinfection by-products, the oxidation of NOM by ozone and the resulting increase in organic matter with a low molecular lead to an increase in the haloacetonitrile precursors compared to the raw water and the formation of chloropicrin precursors.

A contemporary biostability assessment of raw and treated water requires determination of biodegradable organic matter fraction responsible for bacterial growth. BDOC test allows monitoring of bacterial growth by assaying chemical changes in the test-water and thereby determine the content of biodegradable dissolved organic carbon (BDOC). The aim of this study was to optimize the required period for performance of BDOC tests, and to examine the use effectiveness of different biofilm carrier. The results indicate that the BDOC test with sand-inoculation is more effective compared to the anthracite, and recommendations for monitoring of biodegradation process are a period of 3-5 days.

The content of aluminum, boron, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, cadmium, barium and lead was analyzed in raw water and drinking water that is used by the Belgrade Water Supply and Sewage Company. Total of 14 samples were examined from all water treatment plants that are part of the Belgrade Water Supply and Sewage. The measurements were conducted using the inductively coupled plasma-mass spectrometry (ICP-MS) technique. The aim of this research was to examine the effectiveness of the process of drinking water preparation in the existing plants. In all drinking water samples concentrations of the elements were bellow the maximum allowed levels according to the Serbian regulations. Correlation coefficients for the elements, which were analyzed in this paper, show that three groups of elements can be distinguished. Boron, manganese, arsenic and barium are related to each other and probably originate from the same source; copper, nickel and zinc have lower mutual correlation coefficients, indicating a potential common origin; finally, lead, aluminum and cadmium are not in correlation with any tested element.

The microbiological quality of the groundwater was monitored by determining relevant physiological groups of bacteria (organotrophic bacteria) which are indicators of water organic pollution. Standard high nutritive medium (Nutrient Agar) and low nutritive medium (R2A agar) were used. The enzymatic activity was also estimated based on IFA determination (index of phosphatase activity). According to the number of organotrophic bacteria and categorization by Kohl (Kohl, 1975) water is generally classified in category II. IFA showed variation of water quality, which varied from polluted to very pollute. The results showed organic pollution of groundwater and confirmed the sensitivity of enzymatic methods. In addition, cultivation methods confirmed superiority of low nutritive media.

The Rapid Small Scale Column Test (RSSCT) was developed to predict the adsorbtion of organic compounds in activated carbon adsorbers. In the RSSCT, a small column, which is loaded with an adsorbent ground to small practicle sizes, is used to simulate the performance of a pilot or full scale system. Due to the similarity of mass transfer processes and hydrodynamic characteristics between the small, pilot and full-scale columns, the breakthrough curves are expected to be similar. Due to its small size, the RSSCT requires a fraction of the time and water volume compared to pilot column testing. Recently the RSSCT has been used successfully in simulating the performance of metal-oxide based arsenic adsorbers. The adsorptive-filtration column was scaled down to mimic the performance of continuous flow, full and pilot scale arsenic treatment systems using the RSSCT approach. This paper investigates the application of the RSSCT method for assessing arsenic removal by unconventional adsorptive media such as waste materials.

This paper examines the impact of ozonation (0.4 to 3.0 mg O3/mg DOC) and the Peroxone process – O3:H2O2 (0.4 to 3.0 mg O3/mg DOC; O3:H2O2 = 1:1) on the content of natural organic matter (NOM) in water. It was found that the Peroxone process results in a greater degree of total organic matter content removal (up to 81% UV254), but also oxidises a greater amount of hydrophobic NOM compared to ozonation. Ozonation was more effective for the removal of the specific haloacetic acid (HAA) precursors (29-50% HAAFP), whereas the Peroxone process was more effective in the removal of haloacetonitrile (HAN) precursors (19-43% HANFP).

Novi Sad is one of the major consumers of water in the Republic of Serbia. This is why the presence of safe and abundant sources of raw dringing water has been of utmost importance for this city which is expanding urbanistically and demografically. This paper presents major data related, above all, to the capacity of the present water sources in Novi Sad, as well as the results of the analyses considering the possibilities for the expansion of source capacity. Furthermore, the text considers the problem of numerous pollutants which have been polluting water sources and offers possible measures for their efficient protection.

The possibility of applying the process solidification/stabilization for treatment of arsenic containing sludge, obtained after coagulation and flocculation treatment in the preparation of raw drinking water, using lime, cement and lime and cement in the mixture as stabilization agents was examined. Test results showed a high content of arsenic in the initial sample of sludge, above the allowable 41 mg As/kg by the USEPA prescribed for disposal of waste sludge. Performance of S/S process was investigated by two leaching tests, PCLP and DIN 38414-S4 test, which showed the highest efficiency of lime and cement mixture in the removal of arsenic by this procedure.

Arsenic is inorganic spread out in nature. Toxicity of arsenic is different, depending on its form. However, current international and Serbian legislation in drinking water regulate maximum allowed concentration of 0.010 mg/l (of total arsenic), regardless of its form. Concentration of total arsenic in water of springs of mountain Avala (Serbia) is higher than 0.010 mg/l. This paper present determination of inorganic arsenic in drinking water of spring Sakinac (Avala), also determination which form is more represented, relation of As(III) and As(V) and implementation of legislation. We used stripping voltametry method and gain value of total arsenic-62.87 microgram/l, in which 3.97 microgram/l is As(III) and residue of 58.90 microgram/l is As(V). It is obvious that value of 62.87 microgram/l is higher than MAL, but the most abundant arsenic form is less toxic, so the question is whether the water from spring Sakinac can or cannot be used.