RTB Bor smelter and sulfuric acid plant modernization project includes reconstruction of an old wastewater treatment plant (WWTP). The task for a team from the Innovation Center of TMF was technical-technological solution for the reconstruction of WWTP with a new wastewater treatment process. Wastewater from the primary copper smelter is very acidic, with a high content of dissolved heavy metals and arsenic. Treatment of wastewater includes the neutralization of the acid, precipitation of the

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... avy metals in the form of hydroxides by using hydrated lime, and the arsenic co-precipitation with iron(III) hydroxide. Material and energy balances of the process are determined by simulating the wastewater treatment in Superpro Designer software package with thermodynamic parameters defined in HSC Chemistry program. The simulation results were confirmed by experimental tests at the pilot plant level. The designed process is applied in WWTP exploitation within the new copper smelter RTB Bor. Treatment of 8,7 m2/h of wastewater generates 7,2 m2/h of treated wastewater and 10,3 t/h of wastewater treatment (WWT) sludge. The WWT sludge is characterized as hazardous waste requiring treatment prior to disposal. A proposed treatment for WWT sludge is solidification/stabilization (S/S) using a mixture of fly ash and hydrated lime. Results of laboratory scale tests, which included standard leaching tests EN 12457 and TCLP, as well as the compressive strength testing of obtained solidificates, shows that the S/S treatment leads to stabilization of more than 99% of the heavy metals and more than 90% of arsenic. The treated sludge has the characteristics of non-hazardous waste and is suitable for disposal.