Leachability of Immobilized Hydrocarbon Sludge in Zeolite Cement

Volatile organic compounds in hydrocarbon sludge are one of hazardous waste with the potential to contaminate water bodies. Immobilization is practically used to prevent uncontrolled released of toxic substances into the environment by bind into the inert materials like cement and admixtures. An oily component in the waste interferes the immobilization process by retarding the cementation reactions. This work explores immobilization techniques using OPC and zeolite with different water to cement (WC), cement to sludge ratios (CS) and the addition of 5 to 20 wt. % zeolite with the objective of reducing waste mobility. Immobilized sludge was measured by compressive strength, porosity and leachability of metals, and oil & grease. Immobilized sludge at WC 0.35 and CS of 40 achieved 52.55 MPa UCS. Zeolite addition contributes to the increase in accessible porosity but reduces the UCS to a maximum of 31.22 MPa. Incorporation of 10 wt. % zeolite successfully binds the waste indicated by only 0.2 ppm Fe had been released into the leachate. The oil & grease leachability was found below the permissible level while achieved the acceptable compressive strength value of 20.7 MPa.