One of the biggest problems in drinking water treatment is the presence of a high natural organic matter (NOM) content in water resources. This paper presents the results of a study which aimed mainly to determine a combined coagulation and preozonization process application for trihalomethanes and haloacetic acids precursors content in ground water rich in natural organic matter.

This work considers the possibility of enhancing the iron (III) chloride coagulation process in natural organic matter removal by flocculation sludge recirculation. The results show that flocculation sludge has the potential to coagulate organic matter, and shows a dependence on the depth in the precipitator (0, 30 or 70 cm). Recirculation of flocculation sludge at a dose of 1.6 g/l (from a depth of 30 cm), results in a reduction of required coagulant by 25%.

Iron-related well-screen encrustation and aquifer biofouling has decreased the specific capacity of RB-7 well. This paper describes the role of iron-related bacteria in the encrustation process and relates their occurrence to chemical conditions in the well.

Filamentous bacteria are commonly found in activated sludge. If numerous, they can cause bulking problems. In order to control their number in a system detailed identification of filaments is necessary. In Subotica Wastewater Treatment Plant (WWTP) daily analyses of filamentous bacteria were performed from January 2006 till March 2007. The dominant and constantly abundant was Thiothrix sp. The filaments of Haliscomenobacter hydrosis and Type 1863 were also common (moderately numerous with periods when develop massively). Nostocoida limicola was frequent, but not numerous. Sphaerotilus natans was numerous in some periods when even dominant. Type 1701, Beggiatoa sp. and nocardioform actinomycetes were rarely found and were not abundant.

Sea urchin gametes, embryos and larvae can be used for quick, cheap and reliable screening and testing of pharmacologically active substances and pollutants. The results obtained are in many cases applicable to mammals including humans.

Sea urchin, Paracentrotus lividus belongs to Echinoderms and has wide distribution as well in Meditarranean Sea as in the Adriatic Sea. It is very appreciated as object for testing negative impact of pollution, so can be used as bio indicator of sea water and sediments quality. Identification of the presence of this animal is done at 11 locations inside the Bay of Boka Kotorska (Montenegro), during 2005/2006. Obtained results show that the sea-urchin inhabit only outer part of Boka Kotorska Bay, where is open sea impact very strong, while inner part of the Bay is characterized by absence of Paracentrotus lividus, what can be caused by potential low quality of the sea water in the Bay.

In Serbia, in the most cases, drinking water supply is based on alluvial sources. The appearance of nitrate in some important alluvium aquifer has been observed and an increasing of this problem can be expected with a currently tendency for intensifying the agricultural production. Therefore, the used techniques which are able to identify the source of nitrate in groundwaters and existing processes of its reduction will be more and more requested. Simultaneously determination of both nitrogen and oxygen isotopic fingerprints allows us to make a difference between nitrate from artificial fertilizer and manure or animal waste as well as nitrate formed from nitrification of organic material and consequently the dominant source of the nitrate to be indicated. Once the origin of nitrate in drinking water sources is understood, corrective measures may be taken to prevent or minimize further contamination.

The salt pond Velika Slatina is the old meander of the river Tamis (Serbia). The ecosystem is periodically fill with moderate salt water. Phytoplankton production was 10 times bigger in 2003 than 2006. Ecological conditions were unfavourable for development of phytoplankton community. Diatoms show as the most abundant component in 2003, but euglenoids were in 2006, when bloom of Gloeotrichia natans f. bucharica Kissel was recorded. Results of biomass analysis also show dominant role of diatoms in 2003 and euglenoids in 2006.

Investigation in this study should indicate to importance of aquatic macrophytes in accumulation of toxic metals in aquatic ecosystems and control of their pollution, as well as to indicate which plants are well hyperaccumulators and test species for remediation, in order of protection, regeneration and conservation of the Gruza lake as reservoir that is important for water supply and as particular natural ecosystem.

Aquatic macrophytes are exceptional accumulations of heavy metals and they are very important in phytoremediation of the pollutants. The aim of the survey was to show according to content of heavy metals in aquatic macrophytes DTD (Danube-Tisza-Danube) canal complex, at localities under great human influence indicate the situation of chemical contamination these localities and to define test species, actually the ones that have the greatest accumulation. Plant material was prepared according to the Standard Methods for Examination of Water and Wastewater of the American Health Association. Analysis of heavy metals in the plant tissue samples was done by standard methods using atomic absorption spectrophotometry. The best accumulator of majority of heavy metals is Ceratophyllum demersum. The results show that mentioned species can be used for removal of heavy metals from water, what means that it has the ability of phytoremediation of pollutants.