The potential reuse of oily sludges as additive material in brick for building construction

Abstract

The upstream oil industry generates large quantities of oily and viscous residues which are formed during production operation when separating the oil and gas from its produced water and solids. These residues called oily sludge or tank bottom, which are composed of oil, water, solids of sand and clay, with solids often containing traces of heavy metals. The composition of the tank bottom vary and is dependent upon the type of the crude and frequency of the tank cleaning. In general, every tankages may require clean up periodically within 3-5 years or even longer. On the other instances, this separation process produces oily sand or oily sludge continuously. Conventional physical and chemical methods of treatments of oily sludge or tank bottom focus on the recovery and reuse of the oil. Centrifugation, liquidliquid hidrocyclone, and torque are among the usually used methods to separate the oil, water and the solids. The saleable oils are returned to storage. The produced water is treated to reduce its oil content prior to release to the environment or injected back through injection well and the solids are backfilled on site. Should the solids still containing significant amount of oil, than bioremediation method of landfarming, composting and biopile is normally exercises prior to backfill. Alternative processes are solidification and stabilization such as with cement or bentonite prior to backfill, while landfill is not a favorite choice in the upstream oil industry considering of its future liability. If it is not treated properly, oily sludge or tank bottom may fall under category of hazardous waste and it must be disposed off accordingly. * Sekolah Tinggi Teknik Lingkungan “YLH” Yogyakarta ** Unocal Indonesia Company Therefore, several PSC’s companies in Riau have reviewed a third party proposal for the possibility to reuse the oil field oily sand as the major constituent for road construction materials and have implemented a pilot plant accordingly. Those PSCs companies has reviewed also a third party proposal for the possibility to use the oil field oily sand as the major constituent for brick making within the field operational areas. These are not the scope of this paper. This paper discuss study conducted to reviews the opportunity to reuse the oily sludge or tank bottom resulting from the oil and gas, water and solids separation process i.e. as additives material in brick making to be used for construction. The reuse of oily sludge or tank bottom as additive material in the construction has a benefit not only in reducing the amount of waste material requiring treatment and disposal, but can provide a new construction material. In this research, we use oily sludge which was taken from the oil & gas and water separation process from one of the PSC company at East Kalimantan. The clay was added to the oily sludge respectively at 90%; at 80%; at 70%; and at 60%. The 100% clay is also used for control. To determine the optimum concentration of clay that are acceptable for construction and will not leaching to the environment, a series of various physical and chemical testing was conducted. The test is including crushed test and leaching test for total mercury concentration.