Three wells lying downstream of the Kirbet es-Samra sewage treatment plant (KS) waste stabilization ponds, and two wells lying upstream of them were monitored. Historic results over the two past decades were used in evaluating of KS effluent on the groundwater resources of the area. Prior to 1985, the downstream wells were of high quality, but later the water started to deteriorate. An increases in all parameters was encountered, although initially, the increase in certain parameters was mild and due to overpumping of the well water. Later this increase continued at a much higher rate, although the water table in the area by some 20m with a variety of indications showing domestic wastewater pollution effects. Groundwater measurements indicated a recharge mouth in the KS area and along Wadi Dhuleil. Hence, it can be deducted that a source of inferior water quality is recharging the groundwater and causing this increase in parameters. Since no source of pollution other than KS is encountered in the area, and because the parameters in the groundwater increase towards the KS and Wadi Dhuleil, it can be deducted that the effluent from KS is polluting the groundwater and rendering it unsuitable for almost all purposes. Comparatively, the two sample wells taken upstream of KS showed a mild increase in the water quality parameters until 1981-82, due to overpumping of the well water. But due to several wet years, the water table rose and these values decreased, continuing at a constant level. Since the groundwater flow is in the direction of Wadi Dhuleil, the negative effect of KS on groundwater resources can be clearly seen. If not stopped, this continuous manipulation of the groundwater resources will further pollute the groundwater resources of the entire area

Content of arsenic in groundwater form south Banat which are used for water supply of local population was determined. 228 wells were analyzed, and for arsenic determination was used atomic apsorption spectrometry - graphite furnace technique (Perkin Elmer Analyst 700). Arsenic is detected in concentrations over 10 microgram/l in several locations: Pancevo (water supply Filter Stanica, Gradska Suma, OB, and in part of water supply Sibnica), Kovin, Dubovac, Idvor, Veliki Gaj, Glogonj, Sefkerin and part of Sakule. The lowest concentrations of arsenic are detected in the territory of Deliblatska Pescara and municipalities of Vrsac and Bela Crkva.

Parallel with the ground water physico-chemical quality examinations and the other long term exploring works on the infiltration wells of the Belgrade (Sava alluvium) and Trnovče (Velika Morava alluvium) groundwater sources the microbiological, chemical and crystallographic analysis for the ocher from horizontal drains walls, pumps and discharge pipelines were carried out. One of the objectives of this paper is showing the importance of eco-physiologic groups of bacterium which initiate the aging well processes with their life activities. In ocher, bright field microscopy and SEM analysis determined the presence of genera and species of iron-manganese oxidizing bacteria. Mineralogical – crystallographic content were determined using SEM –EDS, X –ray fluorescence and XRD-methods.

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.

Water wells are among the oldest hydraulic engineering structures in the world. Today, hundreds of water wells service water supply systems in Serbia, and groundwaters are widely used for public water supply. Extensive practical engineering experience in water well operation has identified a number of problems which affect well service life and capacity (i.e. reduce specific yield). Some of the encountered problems are, also, a result of microbial activity in groundwater. Products of life processes of groundwater specific microbial community cause biocorrosion, blockage, closure, plugging, deposition, and biofouling of well screens and collectors. We applied BART biodetectors as a reliable tool in monitoring well rehabilitation effectiveness. This paper presents several process assessments based on BART biodetector tests conducted at Belgrade groundwater source.

Factors controlling of arsenic content in underground water are commented on the base of experimental obtained results of analysis of water quality from October to November 2006. The influence of water quality parameters and temperatures of water on examined locations of waterworks of middle Banat, south from Zrenjanin, public wells in Zrenjanin and waterworks north from Zrenjanin, on arsenic content is found.