The possibility of applying the process solidification/stabilization for treatment of arsenic containing sludge, obtained after coagulation and flocculation treatment in the preparation of raw drinking water, using lime, cement and lime and cement in the mixture as stabilization agents was examined. Test results showed a high content of arsenic in the initial sample of sludge, above the allowable 41 mg As/kg by the USEPA prescribed for disposal of waste sludge. Performance of S/S process was investigated by two leaching tests, PCLP and DIN 38414-S4 test, which showed the highest efficiency of lime and cement mixture in the removal of arsenic by this procedure.

Quality of groundwater from aquifers used for water supply in the town of Zrenjanin, does not meet the drinking water quality requirements. Among the basic problems are the high content of natural organic matter and arsenic, but also sodium and boron. This paper presents one of possible alternative of technological solutions for drinking water preparation in Zrenjanin. Research has lasted three years. The paper presents a only an outline of the drinking water preparation processes.