According to existing national Standard for drinking water quality NO3 sup(-) ion is limited to 50 mg/l. Removal of NO3 sup(-) concentration greater than this limit is necessary. One of the possible methods is biological denitrification with CH3OH. Principals of this method are described in this paper with recommendation for construction of pilot plan on the specific groundwater source.

The paper deals with pilot-scale investigations of the effect of preozonation on NOM removal from groundwater by coagulation and flocculation processes. It was found that the preozonation increased the efficiency of organic matter removal by coagulation and flocculation from 23.6 to 47.2% as judged on the basis of KMnO4 values. From the aspect of the change of content of trihalomethanes precursors preozonation exhibits both the positive and negative effects if their content in the water after coagulation is considered in dependence of the applied ozone dose. The obtained values siggest the necessity of careful optimization of the processes of preozonation, coagulation, and flocculation, especially from the aspect of the change in content of the precursors of disinfection byproducts.

The lack of drinking water in Zajecar was the main reason for building of water barrier on the Grliste river and making the water reservoir. A factory for water processing was also built, but the problems were not disappeared. The conclusion is that the main solution for this ecosystem was in establishing of an monitoring system. That is the reason why we talk out the results of the monitoring and the troubles in this water source as well as in the phases of water processing.

Concentrations of nitrate above defined levels for portable water are present in most of the groundwater sources in Velika Morava river alluvion. Some problems exists in Meminac and Kljuc, groundwater sources of Pozarevac town. Some detail investigations were organized in 2002. Survey of groundwater quality in the wide surrounding of Kljuc confirmed some earlier made assumptions about influence of agriculture and sewage water, and their contribution to existing groundwater quality.

Membrane processes is gaining broad application in potable water treatment. Experience in application of membrane system for treatment of potable water so far showed that these systems have wide range of advantages versus conventional treatment: lower capital costs, lower operation costs, use of chemicals is minimal; space for installation is much smaller, usage of chlorine for disinfection is minimal due to significant reduction of microorganisms; sludge production during the process is smaller due to smaller usage of chemicals, construction period is shorter due to smaller scope of works and relatively simply installation of membrane batteries.

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.