Stable complexes formation caused by usage of complexing agents as additive in plating solutions, made waste water treatment aggravated and expensive. The investigation results of samples that contain some cations expected in waste waters from this type of facilities, are presented in this paper. The precipitation of disolved heavy metals by neutralization, in the presence of strong chelators, do not give requested results. The dithiocarbamates are effective in complexing heavy metal ions forming insoluble compounds, with solubility far below that of the corresponding hydroxides. Inductively Coupled Plasma Optical Emission Spectroscopy is used for wastewater samples analysis. After the reduction of Cr6+ into Cr3+ ions and homogenization, dithiocarbamate is added. Modified neutralization process with unchanged retention time and pH 9.0 +/- 0.2 results the Law permitted wastewater quality.

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.

In this paper there are presented the results of organic matter index, as dominant component of unsettled water of settlement, which after specified time locate into deeply karst underground appear on spring of river. Obtained results showed that into deeply karst underground has become to certain level of autopurification, which reflecting values of index this loading on the water of spring - river.

In order to investigate the effects of wastewater from the Vrbas-Kula-Crvenka industrial basin on Grand Backa canal water quality, the water quality in the canal and the lateral canals which fall into the Grand Backa canal was examined, along with industrial water quality for ten of the most important polluters of those canals. A significant deterioration of Grand Backa canal water quality downstream of the lateral canals I-61 and I-64 was detected, as a consequence of waste water emission from the Vrbas-Kula-Crvenka industrial basin polluters. Data analysis has shown that two sugar factories are the heaviest polluters in the examined industrial basin.