Long-Term Leaching Behavior of Petroleum Sludge Waste Containing Palm Oil Fuel Ash and Quarry Dust by Using Solidification/Stabilization Method

Abstract

In recent years, petroleum industry has generated huge amount of petroleum sludge. There are many types of treatment method in petroleum sludge (PS) and one of the treatments that arise the attention to treat the sludge is solidifica-tion/stabilization (S/S) method as it immobilizes and stabilizes the hazardous substances within a solid matrices. The main objectives of this research are to formulate the correct mixture of PS in S/S matrices and to stimulate the long-term leaching behaviour of S/S matrices in PS treatment with palm oil fuel ash (POFA) and quarry dust (QD) as partial cement and sand replacement respectively. The characterization of PS, POFA and QD were done by using X-Ray Fluorescence (XRF). Furthermore, different percentages of petroleum sludge (control, 0%, 5%, 10%, 20%, 30%) were incorporated with fixed 10% of POFA and 20% of QD replacement into S/S matrices. This research also includes a comparison of two different leaching test parameters such as liquid to surface area ratio, pH, and type of leaching solution on the samples. The leaching test conducted namely are Semi-Dynamic Leaching procedure (SDLP) and Static Leaching Test (SLT). The leachability results from SDLP and SLT indicated that all concentration for nine (9) heavy metals were below the permissible limit set by United States Environmental Protection Agency (USEPA, 1996) standards. In addition, the S/S effectiveness was evaluated by measuring effective diffusion coefficients (De) and leachability index (Lx). Results of S/S treatment shown that De values were lower and Lx values were higher than 8 thus the S/S can be disposed in sanitary landfill. As a conclusion, the results for the leaching behaviour of PS up to 10% incorporated with 10% of POFA replacement in cement and 20% of QD replacement in sand demonstrated minimum leaching of the heavy metals from S/S matrices. This indicated that S/S method could be an alternative disposal method for PS and has potential for replacing other treatment methods that applied at treatment stage for petroleum refinery effluents.