The results of microbiological analyses of raw water of two water supplies of city of Novi Sad (Ratno Ostrvo and Petrovaradinska Ada) are presented. The sampling was performed monthly during 2008 and 2009. The following parameters were monitored: aerobic mesophilic bacteria count at 37 deg C, organotroph count (water categorization according to Kohl), facultative oligotrophs, lipolitic and hydrocarbon-oxidizing bacteria count. The count of organotrophic bacteria was determined using low nutritive R2A medium. In addition, water was classified according to enzymatic activity of water, expressed as index of phosphatase activity (IFA).

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.

The paper presents aquatic macroinvertebrate community at four investigated localities of the Gradac river. Sampling was carried out during 2003 and 2006. Community structure and composition, together with field data, were used to estimate the water quality status of the river. A total of 87 taxa have been recorded. Insects were found to be the most diverse component, especially Ephemeroptera. Insects were dominant in the regard of the quantitative structure of the community, as well. Recorded community indicates good water quality, ranged between oligosaprobic and beta-mesosaprobic status (1st-2nd class according national classification scheme).

The analysis of breaks and gaps frequences in the fish species Alburnus alburnus from different localities of rivers Kolubara, Sava and Danube, were showed the highest values that were above the presumed critical zone (3.0-3.5% of changes). At some of localities examined in May and October 2008, these values were much more elevated that the level of spontaneous changes normally seen in the controls in laboratory animals and in fish of relatively clean waters. Results that were obtained for these localities indicate to periodical or permanent contamination with genotoxic agents.

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.

It has been established that processing by CTA - peat, under normal pressure, significantly reduces COD of tested wastewater, but at the same time, quickly comes to a stoppage, due to clogging. Results show that filtration process needs to be done under increased pressure. Based on gained results it could be concluded that CTA-peat represent efficient means of eliminating organic matters from wastewaters.

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.

In order to protect the natural resources used, it is necessary that plant production has such a concept that its influence with the optimization minimizes the required yield. For this purpose it is necessary to adjust the measures taken for the purpose of regulation of water-air regime, especially in the area where land reclamation is applied. The difficult task require harmonization of approaches that are often contradictory, therefore it is necessary to make preparations for the changes in the existing principles of the existing land reclamation practices. These changes reflect primary in the rational use of resources that could result in the protection and improvement of biodiversity and therefore stable ecosystem in the agricultural area.

The aim of this paper is to present the current distribution of the species Corbicula fluminea and Corbicula fluminalis with new findings in Serbia. During the investigation performed from 1998-2008, these taxa were detected at 19 localities. It is noted that C. fluminea is well adapted to particular aquatic ecosystems, whereas C. fluminalis seems to be rare in Serbian waters. Wide distribution of alien clams, according to our results, showed that heavily modified main water ways are suitable recipient areas for introduction and adaptation of allochthonous organisms.