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Shaily MahendraScientific Advisory Board
Shaily Mahendra

Professor
University of California, Los Angeles

 

Dr. Shaily Mahendra is a Professor in the UCLA Department of Civil and Environmental Engineering, and a member of the California NanoSystems Institute, Institute of the Environment and Sustainability, and the Molecular Toxicology Program.  She received Ph.D. from University of California, Berkeley, and post-doctoral training at Rice University.  Her research areas are microbial processes in natural and engineered systems, applications of molecular and isotopic tools in environmental microbiology, environmental applications of nanomaterials, and biotransformation of emerging water contaminants, such as 1,4-dioxane, BPA analogs, pharmaceuticals, insensitive munitions, and PFAS.  She received the NSF CAREER Award, DuPont Young Professor Award, Northrop Grumman Excellence in Teaching Award, Samueli Fellowship, Hellman Fellowship, Poptech Science and Public Leadership Fellowship, ASCE Walter Huber Civil Engineering Research Prize, and Paul Busch Award from the Water Research Foundation.



PLATFORM PRESENTATION

Biodegradation-Ultrasonolysis Treatment for the Destruction of Per- and Polyfluoroalkyl Substances in Mixtures

Shashank Singh Kalra,† Brian Cranmer,‡ Gregory Dooley,‡ Sanjay Mohanty,† Jens Blotevogel,# and Shaily Mahendra,∗,†

†Civil and Environmental Engineering, University of California, Los Angeles 5732 Boelter Hall, Los Angeles, 90095, California, United States ‡Environmental and Radiological Health Sciences, Colorado State University, 1680 Campus Delivery, Fort Collins, Colorado 80523, United States #Center for Contaminant Hydrology, Colorado State University, 1320 Campus Delivery, Fort Collins, 80523, Colorado, United States E-mail:

We explored biodegradation combined with ultrasonic nanobubble-catalyzed destruction of individual per- and polyfluoroalkyl substances (PFASs) as well as their mixtures in Investigation Derived Waste (IDW) and Aqueous Film Forming Foams (AFFF). The experiments were performed in a polypropylene/stainless steel reactor equipped with ultrasonic transducer operating at 900 kHz and 300 W. The cavitation of high-energy bubbles under high acoustic pressure caused pyrolysis of PFAS mixtures resulting in the mineralization of most non-fluorinated, polyfluorinated, and some perfluorinated constituents. In independent biodegradation experiments, individual PFASs and certain AFFF components were aerobically transformed by the fungus Trametes versicolor as well as by pure laccase enzymes within 19 days of incubation. To reduce the energy demand of sonolysis and to decrease the timeframe of biodegradation, a treatment train was developed, in which the AFFF was first treated with laccase derived from T. versicolor followed by ultrasonic treatment. Our data indicate that biological-abiotic treatment trains can be customized to lower the overall time and energy requirements for destroying PFAS mixtures in waste streams and contaminated waters.


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