Research and development on low level liquid waste treatment in Thailand

The studies have been directed towards several subjects concerning the treatment technologies of low level waste. The simple physico-chemical method has been studied for applying to many kind of waste streams such as reactor waste, isotope production waste and liquid waste from the hospital. The characterization of inorganic ion-exchangers including the effect of pH, equilibrium time, temperature and concentration of such ion-exchangers were tested and the optimum condition of the sorption of C x on the exchangers are reported. The results from the investigation on the efficiencies of detergents in the radioactive decontamination reveal that the local simple brand machine-washed detergents. which is very cheap, can be best used as the decontaminating agent instead of the more expensive imported one. It is found that chemical precipitation methods i.e. phosphate coagulation, copper ferrocyanide coagulation and cobalt precipitation method can be used for treating of the waste stream arising successfully. In considering of the immobilizing process of treated waste, cementation is advised to be used and, therefore, subjects to be evaluated. The basic properties of cement-waste products as well the leachability of a particular types of sludge waste at 15-40% waste loading were investigated. The result reveals that, cement waste forms of inorganic ion-exchanger and of sludge waste from chemical precipitation of decontamination waste, exhibit high compressive strength and a low leach rates. The compressive strength of 118-207 Kg/cm2 were found for the optimum waste products originated from various exchangers and 15-20% loading of sludge waste. The leachability of Co-60, Cs-134 and Sr-85 from 15-40% loading of cement waste for 30 days were studied. The cumulative fraction leached rate of Cs-134 from sludge-cement wastes was found to be about 17 x 10-3 g/cm2 for 25 degree C and 50 degree C at 30 days leaching time respectively, while there were no leaching of Sr-85 and Co-60 at any condition