This paper presents results of wastewater examination from Belgrade sewerage system (BKS) which are discharged into the river Sava (Fair) and river Danube (Visnjica). Examinations were conducted within the project Eight monitoring spots and are compliant with European Directives concerning wastewater management. Project Eight monitoring spots consist of: continuous measurements of physical and chemical parameters (pH, temperature, redox potential and conductivity), sampling of wastewater during 24 hours, measuring flow rate and analyzing the quality of wastewater from monitoring places located at the discharges into rivers Sava and Danube. This paper shows examination results collected at two discharge points out of eight which are included in this project. The analysis of the quality and the quantity of wastewater sampled continuously during 24 hours, the effects of industrial pollution on them and total pollution load from these two collectors on the recipient is given.

Paper presents an overview of wastewater treatment systems with macrophytes. It is concluded that application of these systems in Mediterranean countries is feasible, especially for treatment of smaller and remote wastewater point sources.

In this paper the results of preliminary investigations of microbiological quality of seawater and sediment are presented. Analyses are performed by membrane filtration. The samples were collected near the sawage outfalls in Bokakotorska bay. It is noticed much higher number of bacteria – indicators of fecal pollution in sediment surface that seawater overlaying the sediment. Concentrations of bacteria diminished in layers of sediment laying deeper that sediment surface. Influence of wastewater is the most evident on 1 and 3 positions.

The papar deals with the possibility of different types of seas protection from ballast waters, starting with administrative measures up to the technologies proposals by which those waters could be treated. The problem of ballast waters in the Montenegrin part of Adriatic Sea is in focus in this paper, and the proposal for protection measures are elaborated.

Water bodies like rivers and lakes are directly affected by the waste water in sewerage systems. Sewage systems provide waste collection and convey wastewater from the population in sanitary safely way and away from material property. DPSIR analytical framework allows the analysis of interactions between sewerage systems and water bodies. Sewer systems describe the different standards that are elements of their functioning including plants and their maintenance, hydrological, hydraulic and other influences. This paper gives analytical framework of Driver, Pressure, State, Impact, Response (DPSIR) in relation to the functioning of the elements considered sewage systems which are described in the Serbian (European) standard - SRPS EN 752 - 2:2007.

In Laboratory for examination of waste waters in Belgrade sewerage system many analysis are being done to indicate the physical, chemical and biological characteristics of waste waters. Biochemical analyses which are being done include two parameters: biochemical oxygen demand (BOD) and newly introduced parameter index of phosphate activity (IFA). Determination of IFA is relatively fast biochemical method which can, within few hours, give information of present organic pollution and its results could be applied for categorization of waters. Analyses were conducted during 2008 and according to the results waste waters mainly belong to the 5th category of water, more, the examined waste waters were out of all water describing categories.

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.

During 2005-2006 the seasonal researches were taken place aiming to investigate the influence of the urban waste water on the qualitative and quantitative structure of the community of macrozoobenthos in Gabrovacka river. For this purpose five sites were determined and the sampling of the macrozoobenthos was organized on the seasonal level using Surber net.

Microthrix parvicella is dilamentous bacterium common present in the activated sludge on the plants with biological nutrient removal. Microthrix parvicella is described as a bacterium which present in a large numbers, has an extremely negative impact on the sludge settling, and its considered as the primary cause of bulking sludge on the WWTP-s with biological nutrient removal. Also, this bacterium considered as the primary foam-forming microorganisms in activated sludge, because those hydrophobic cells stabilized air bubbles or affected by the oil droplets in foam. Although there are numerous data regarding the growth of certain filamentous bacteria, as well as their impact on the waste waters treatment and deposition of sludge, they are often vague, and not always in clear correlation, especially when comparing data from different plants. The aim of this paper was toexamine the growth and population size of Microthrix parvicella in correlation to water temperature (seasonal dynamics of growth), and a correlation between population size of filamentous bactereia (filamentous sludge index-FI), especially M. parvicella growth and the sludge settlement (Imhoff 30 '), or the ratio of FI and the volume of sludge (sludge volume index – SVI) on WWTP of Subotica during 2011.

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.