Removal of Oil from Gas Station Runoff Using Biomass

Abstract

The uses of biomass sorbents, which are less expensive and more biodegradable than synthetic sorbents, for oil removal from gas station runoff were investigated. Benchscale flume experiment was conducted to evaluate the oil removal and retention capabilities of biomass sorbents which included kapok fiber, cattail fiber, Salvinia sp., wood chip, rice husk, coconut husk, and bagasse. Polyester fiber, a commercial synthetic sorbent, was also experimented for comparison purpose. Oil sorption and desorption tests were performed at a water flow rate of 20 L/min. In the oil sorption tests, a 50 mg/L of used motor oil-water mixture was synthesized to simulate the gas station runoff. The mass of oil sorbed for all sorbents, except coconut husk and bagasse, was greater than 70%. Cattail fiber and polyester fiber were the sorbents that provided the least average effluent oil concentrations. Oil selectivity (hydrophobic properties) and physical characteristics of the sorbents were the two main factors that influenced the oil sorption capability. The used sorbents from the sorption tests were employed in the desorption tests. Results indicated that oil leached out of all the sorbents tested. Polyester fiber released the highest amount of oil, approximately 4% (mass basis) of the oil sorbed.