Development and testing of a new protocol for evaluating the effectiveness of oil spill surface washing agents

As defined by the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), a surface washing agent (SWA) is a product that removes oil from solid surfaces, such as beaches, rocks, and concrete, through a detergency mechanism and that does not involve dispersing or solubilizing the oil into the water column. Commercial products require testing to qualify for listing on the NCP Product Schedule. Such testing is conducted both for toxicity and effectiveness. Protocols currently exist for bioremediation agents and dispersants, but not SWAs. The US Environmental Protection Agency (EPA) is developing a laboratory testing protocol to evaluate the effectiveness of SWAs in removing crude oil from a solid substrate. This paper summarizes some of the defining research supporting this new protocol. Multiple variables were tested to determine their effect on SWA performance. The protocol was most sensitive to SWA-to-oil ratio and rotational speed of mixing. Less sensitive variables were contact time, mixing time, and SWA concentration when total applied mass of active product was constant. EPA recommendations for the testing protocol will be made following round robin testing.