Leaching Behavior of Coal Combustion Products and the Environmental Implication in Road Construction: Project Progress Report [January 2009]

2009PDFTech ReportNUTC R201Report No. 00017576DTRT06-G-0014 (Grant)Fly ashLeachingCombustion depositsAntimonyArsenicCoal combustion productsMissouriUnited States. Dept. of Transportation. Research and Innovative Technology AdministrationWang, JianminUniversity of Missouri--Rolla. Dept. of Civil EngineeringUnited States. Department of Transportation. Research and Innovative Technology AdministrationUniversity Transportation Centers Program (U.S.)US Transportation CollectionThe use of coal fly ash in road base and sub-base applications can provide better properties and performance, and is superior to it being otherwise disposed and becoming a possible environmental liability. Understanding the metal leaching behavior for various fly ashes can help the construction industry and the energy industry in selecting the environmentally benign fly ash for road construction and for other beneficial use applications, and determining the long term environmental impact of fly ash during road construction. Coal fly ash contains many regulated cationic and oxyanionic elements such as antimony, arsenic, barium, boron, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, and selenium. Due to the implantation of several new air emission control regulations, future fly ash may contain elevated concentrations of volatile trace elements especially oxyanionic elements. Since oxyanionic elements have greater mobility in the environment, being less studied previously, and are generally more toxic than cationic elements, understanding the leaching behavior of oxyanionic elements from fly ash is significant in determining the potential environmental impact of fly ash during disposal or beneficial use, selecting the appropriate fly ash for road construction, and developing methods to control the leaching of oxyanionic elements. This research becomes more urgent due to the implementation of more stringent arsenic standards in drinking water that will become effective in January 2006. This research will focus on the leaching behavior of 6 major oxyanionic elements, antimony, arsenic, boron, chromium, molybdenum, and selenium, for various fly ashes under different management scenarios, using both batch and column experiments. Mathematical models will be developed to quantify the leaching behavior of these elements. Speciation of these oxyanion elements will be determined using the most advanced Perkin-Elmer HPLC-ICP-MS system available at Missouri University of Science and Technology.92