Abstract:
A lab-scale experiment was conducted to investigate the use of sulfur polymer material which involved the reaction of element sulfur with 10 wt% STX[superscript TM] modifier to encapsulate the hazardous and radioactive mixed waste. Selected waste types were sediment sludge from hazardous wastewater treatment facility, incinerator ash, activated sludge and spent ion-exchange resin which the latter three waste types receiving from radioactive waste treatment facility. Waste form formulation was fabricated to determine optimum waste loading and perform the property testing which included the resistant to compressive strength, water immersion, chemical, radiation and leachability. The results from the experiment show that the sulfur polymer waste form of sediment sludge and spent ion-exchange resin have poor quality formulation, therefore, use of sulfur polymer for encapsulation of these waste is not recommended. The sulfur polymer material could be well incorporated with incinerator ash and activated sludge. The optimal waste loading for incinerator ash and activated sludge were found to be 40 wt% and 20 wt%, respectively. At these waste loading formations, the range of compressive strength was found to be 27 - 40 MPa for incineration ash and 8 - 19 MPa for activated sludge which higher than the minimum required compressive strength (0.41 MPa) by USNRC. The radioactive nuclide and heavy metal leachability tests, shows that all specimens tested have radioactive leachability indices higher than the USNRC standard value of 6.0 and have heavy metal leachability values lower than the USEPA standard value. It indicates that the sulfur polymer could retard the release of radionuclides and heavy metals to the environment.