The work is concerned with the possibility of inactivation of galvanic sludge formed in treatment of wastewaters of electroplanting plants by imbedding the waste in a glass material. Glass can be synthesized in contact with the waste by mixing and heating with glass constituents. The efficiency of inactivation was monitored by leaching the obtained materials. The results of leaching tests showed that the highest amount of electroplanting sludge (about 30%) can be inactivated by vitrification of the following mixtures: 26.3% of electoplanting sludge, 43.7% of sand, and 30.0% of Na2CO3 at 1000 deg C; 30% of galvanic sludge, 49% of sand and 21% of Na2CO3 at 1100 deg C.

A short historical review shows that treatment plants have been developed only after problems have occurred. The high diversity pollutants of totally different origins and natures, and chemical and biological characteristics require different tools. A good approach is to select one basic tool and try to integrate tools for other tasks within this main tool. The main tool will be in almost every case (for municipal wastewaters) an activated sludge plant surrounded by other elements of polishing or for the elimination of nitrogen, phosphorus, etc., according to the local situation. Some tasks like elimination of pathogens or eggs of intestinal worms, are automatically performed to a high degree in connection with the task of eliminating degradable organics. Special wastewaters with certain pollutants have to be treated at the place of their origins. For wastewater of agricultural production direct or indirect recycling should be favoured. For wastewater of industrial background containing toxicants, treatment must be economically included in the production process of the main product. Besides this, there appears a multitude of organics of unknown chemical composition and environmental significance. They should be permitted for public application only after lab tests have proved their degradability and the conditions of their degradation. Finally, one should always be aware that treatment plants have to be composed according to local conditions. Depending on the amount and composition of wastes, an integration of tool has to be found that not only meets the demands stemming from the wastewaters but also can be integrated into the existing economical and ecological frame

A series of experiments on biological nutrient removal using suspended growth bioreactor with a various reactor configuration have been conducted during the last five years. The first configuration applied a contact stabilization flowed by a denitrification processes in two sludge system. The two sludge systems mean that the aerobic sludge is recirculated in the aerobic circuit, and the anaerobic sludge is recirculated in the anaerobic circuit. The second configuration was conducted in a contact stabilization and denitrification processes in a one sludge system. The one sludge system meant that there are no separation between aerobic and anaerobic sludge; the aerobic and anaerobic processes are in the same circuit and all sludge are recirculated in the same circuit. The third configuration was performed in anaerobic-aerobic-anaerobic reactors and ended by the clarifier to clarify the biosludge before recirculated to the head of the circuit. This configuration was also using a one sludge system. In those three configurations, the hydraulic detention time in the reactors were varied from 2 to 6 hours, and the sludge age from 2 to 15 days. The results showed that the first configuration gave a very high performance in carbon and nitrogen removal. In terms of TOC [total oxygen concentration], the carbon removal achieved up to 92 percent or in terms of total COD [carbon oxygen demand] up to 80 percent, and 97 percent for total nitrogen removal. On the other hand, the phosphorus removal was only limited to the amount required for cells metabolism. More carbon removal were observed in the second configuration (94 percent of total COD) but less total nitrogen were removed (93), however, phosphorus were removed significantly (up to five times of the cells metabolism requirement). The best results in those three nutrients removal was achieved in the third configuration. No less than 95 percent of total COD and 96 percent of nitrogen removal were noticed, and phosphorus were removed at the level of more than six times of the cells metabolism requirement. The experiments concluded that the phosphorus removal was conducted by the aerobic microorganisms which are alternately treated in aerobic-anaerobic conditions. The degree of removal depended on how long the microorganisms were put in the aerobic and anerobic conditions. If the anaerobic condition was too long, the microorganisms would die, and no phosphorus removal took place. If it was too short, the removal would be less. For carbon and nitrogen removals in the system, the hydraulic detention time in the reactors and sludge appeared as the essential parameters in the process

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.