Effect of chemical and thermal activations on the properties of rice husk ash-based solidified wastes

Strength development leachability and microstructure of heavy metals from the solidified waste using synthesis rice husk ash (sRHA) and lime blended at the weight ratio of 1 1 were used as binders The heavy metal containing sludge was used at the level of 0 wt%, 30 wt%, and 50 wt% dry weight, respectively The sample specimens with and without 1 5 wt% of sodium silicate (SiO2/Na2O = 1 0) were cured under the ambient condition and elevated temperature curing at 50 degrees C for 24 hr Experimental results showed that the introduction of sodium silicate solution and elevated temperature curing to sRHA-based solidified waste containing 30 wt% of heavy metal sludge gave one day strength of 20 kg/cm(2) compared to 0 9 kg/cm(2) for the control example XRD patterns indicated that most metal-sulfides present in the sludge were appeared in the solidified waste and SEM coupled with EDX techniques reveal these metal-sulfide particles were trapped within the lime sRHA matrices In addition cumulative leaching behavior by tank test (EA NEN 7375 2004) showed that solidified waste containing up to 30 wt% of heavy metal sludge was suitable to dispose in a secured landfill