Leachability and Permeability of Immobilized Waste in Activated Carbon Cement Binder

This research studies the waste management of residual petroleum sludge waste that can be retrieved from after the de-cantering stream in a petroleum refinery complex by the application of a technique known as Solidification and Stabilization (S/S). The S/S technique applies a binder, commonly Ordinary Portland Cement, to immobilize and encapsulate the waste to chemically stabilize it, thus, preventing from external chemical reaction with the environment. The objective is to optimize waste to cement and introduce an admixture (activated carbon) ratio based on the unconfined compressive strength as the main criteria. The performance of the S/S is measured through leaching analysis to determine leachability of metal in the leachate, porosity and permeability properties of the stabilized waste with the unconfined compressive strength and its leaching behaviour. It was found that the water to cement ratio, 0.45, cement to sludge ratio, 60 and cement to binder ratio 0.15 gives out the largest unconfined compressive strength of 43.75 MPa compared to the other lower cement to binder ratio. Porosity showed an increase of 31% as 15% activated carbon was added. The metals content in the leachate were relatively low and below the regulated metals content in sludge disposal as outlined in Standard B of EQA 1974.