Biofilm is a complex aggregation of microorganisms, principally bacteria, associated with their extracellular polymers, and surface attached. Many bacteria, mainly saprophytes, but also some oportunistic human pathogens, live in a water sypplying system. Depending on water quality and other factors, these bacteria are able to form biofilms. The formed biofilm is usually resistant to traditional supply system treating methods, including disinfection. The aim of this study is to make a contribution to the knowledge about bacteria Pseudomonas aeroginosa in biofilm structure. By understanding biofilms, wrong interpretation of microbiological results in water supply system samples analyses could be avoided.

Biofilm naturally occurs in many water distributive systems. The aim of the paper is to determine biofilm forming potential of bacteria isolated from tap water from Novi Sad. A colometric crystal violet microtitre plate test was used to determine bacterial potential to form biofilm. The results show that some isolates have a great potential to form biofilm, especially when grow on higher temperature and in the reach nutritive media.

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.

One of the last stages in purification of waste water is by aquaculture pond using macro biological cells - fishes. In such outdoor ponds, oxygen depletion events can occur at anytime, but most likely to cause fish kills during summer hot weather. Aquaculture pond model can predict dissolved oxygen using small number of measurements and very simple numerical model. Alarm system can be activated urgently when the oxygen level drops below a certain concentration, depending on fish species. Such a model is realized for WWTP at Citluk coal mine, close to Sokobanja in Serbia, and explained in this paper.

The length - weight relationship of juvenile anchovy, Engraulis encrasicolus at Bokakotorska Bay (Adriatic sea, Montenegro) was analyzed. The better knowledge of juvenile growth needs more attention for the entire Adriatic, especial for the Montenegrin coast were this investigation made for the first time. The results obtained from this investigation were compared with the data obtained from the period 1989-1991 from the area of Novigrad Sea of the the eastern Adriatic coast (5).

The red algae Womersleyella setacea is Indo-Pacific species but introduced to Mediterranean Sea were is now relatively widely distributed. During research of benthic communities in Ponta Veslo locality (Lusnica peninsula, Montenegrian coast, Adriatic sea) in summer 2007 dense assemblages on rocky substratum and on sea grass Posidonia oceanica (L.) Del. rhizomes were discovered. The impact on biocenosis structure is discussed.

In this paper some results of investigations of physical, chemical and biological parameters were presented from the parts of Montenegrin coastal sea exposed to the impact of the open waters of the Southern Adriatic sea. As Herceg Novi area is simultaneously the part of the Boka Kotorska Bay (which goes deeply to mainland), eutrophication is more visiable there. Biological parameters were the most visiable indicators of eutrophication during these investigations.

The groundwater quality on the National Park Kopaonik is determined by the chemical and radioactive structure of water, formed through the processes that due to the contact of minerals from the water - bearing rocks and groundwater. Atmosphere precipitation are the main source of the entire resources of the ground water in the national park, and the aggressive components that are carried into the underground are the main catalyst in the process of leaching of the predominant minerals from the water-bearing rocks. In the national park, crystalline and marble limestones have the greatest water potential in the sense of the quantity and quality, and the granite massif dispose with the ground water, with the most complex radioactive structure.