Rolf Halden, PhD, PERolf is a Professor of Environmental Engineering and Founding Director of the Environmental Security program at Arizona State University's Biodesign Institute. He has 20 years of experience in ex situ and in situ remediation approaches. Rolf has authored over 100 peer-reviewed papers, reports, patents, and book chapters, and has presented over 200 papers at national and international symposia, with much of his work focusing on in situ remediation and biological treatment technologies for traditional and emerging contaminants. Rolf was a co-founder of the Center for Water and Health at Johns Hopkins University, where he maintains an adjunct faculty appointment. Prior to joining academia, Rolf was a staff scientist and project manager at the Lawrence Livermore National Laboratory, where he conducted feasibility studies and directed the construction and operation of physical and biological groundwater treatment systems.