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• • <br />Chapter 4-Site-Specific Industrial Storm Water BMPs <br />• <br />• <br />Sorbents <br />What Are They <br />Sorbents are materials that are capable of cleaning up spills through the chemical processes of <br />adsorption and absorption. Sorbents adsorb (an attraction to the outer surface of a material) or <br />absorb (taken in by the material like a sponge) only when they come in contact with the sorbent <br />materials. The sorbents must be mixed with a spill or the liquid must be passed through the <br />sorbent. Sorbent materials come in many different forms from particles to foams. Often the <br />particles are held together in structures called booms, pads, or socks. Sorbents include, but are <br />not limited to, the following: <br />• Common Materials (clays, sawdust, straw, and flyash) -Generally come in small particles <br />that can be thrown onto a spill that is on a surface. The materials absorb the spill by taking <br />up the liquid. <br />• Polymers (polyurethane and polyolefin) -Come in the form of spheres, beads, or foam <br />tablets. These materials absorb a chemical spill by taking up the liquid into their open-pore <br />structure. <br />• Activated Carbon-Comes in a powdered or granular form and can be mixed with liquids to <br />remove pollutants. This sorbent works by adsorbing the organics to its surface and can be <br />recycled and then reused by a process called regeneration. <br />• "Universal Sorbent Material"-Is a silicate glass foam consisting of rounded particles that can <br />absorb the material. <br />When and Where to Use Them <br />Sorbents are useful BMPs for facilities with liquid materials onsite. Timing is important for these <br />practices. To be effective as a storm water BMP, cleanup must take place before a rainfall. <br />Sorbents are often used in conjunction with curbing to provide cleanup of small spills within a <br />containment area. <br />"Universal Sorbent Materials" are suitable for use on many compounds including acids, alkalis, <br />alcohols, aldehydes, arsenate, ketones, petroleum products, and chlorinated solvents. <br />Activated carbon is useful for adsorbing many organic compounds. Organics that are diluted in <br />water can be passed through a column that is filled with the activated carbon material to remove <br />the organics, or the activated carbon can be mixed into the water and can then be filtered out. <br />Polyurethane is good with chemical liquids such as benzene, chlorinated solvents, epicholorhydrin, <br />and phenol. Polyolefin is used to remove organic solvents, such as phenol and various chlorinated <br />solvents. The beads and spheres are usually mixed into a spill by use of a blower and then are <br />skimmed from the top surface by use of an oil boom. <br />More common materials such as clay, sawdust, straw, and fly-ash can be used for a liquid spill on <br />a surface that is relatively impenetrable, and are usually spread over the spill area with shovels. <br />Booms, pads, and socks are also useful in areas where there are small liquid spills or drips or where <br />small amounts of solids may mix with small amounts of storm water runoff. They can function <br />4-33