High-Performance Treatment of PFASs from Investigation-derived Waste: Integrating Advanced Oxidation-Reduction and Membrane Concentration
Jinyong Liu | University of California, Riverside
This project's research team aims to develop an effective and practical treatment train for intensive destruction of per- and polyfluoroalkyl substances (PFASs) and organic co-contaminant in liquid investigation-derived waste (IDW) at Department of Defense (DoD) sites. PFAS defluorination is required for safe disposal of IDW; however, PFASs are recalcitrant to conventional treatment strategies, and many novel treatments under development are not capable of destructing PFASs of various structures at affordable cost under realistic conditions. Furthermore, IDW usually contains a wide spectrum of PFASs and organic co-contaminants, which cannot be efficiently removed through a single treatment. In this project, the researchers propose IDW treatment via advanced oxidation, hydrated electron defluorination, and membrane-based concentration. Such treatment train will be operated at ambient temperature with affordable reagents and processes. A variety of PFASs and organic co-contaminant are expected to be removed from liquid IDW so that the bulk liquid can be safely discharged or reused, and PFASs will be rigorously defluorinated so that there will be no further waste residual to be concerned of. Specific objectives of the project are to optimize each treatment module on contaminant conversion/removal, and investigate the overall effectiveness of the treatment train on IDW treatment.
The treatment train contains four modules: (i) oxidation pretreatment, (ii) nanofiltration (NF)-based concentration, (iii) defluorination using hydrated electrons in a ultraviolet (UV)-sulfite system, and (iv) further oxidation with residual sulfite. Advanced oxidation pretreatment will remove most organics and convert complicated PFASs into relatively labile structures for facile defluorination, and mitigate membrane fouling in the next module. NF concentration will reduce IDW volume and accelerate chemical reactions in the following steps. Intense UV irradiation combined with concentrated sulfite treatment will defluorinate PFASs. Final oxidation using residual sulfite will complement the reductive treatment, so that the partially defluorinated PFASs which are susceptible can be further defluorinated or even mineralized. To achieve a successful IDW treatment, the research team will investigate technical details for the four modules, optimize treatment conditions for each module, and examine the overall performance of the treatment train through product analysis and cost estimation. The treatment train is grounded with the solid preliminary data on successful defluorination of a variety of PFASs. The evaluation of treatment effectiveness is supported by experienced PFAS analysis personnel (co-PI Sun). Additional instrumental support is provided by the Environmental Protection Agency (EPA) lab. Principal Investigator (PI) Liu has obtained comprehensive understanding of defluorination mechanisms by advanced oxidation and reduction in another SERDP project ER18-C2-1289. Co-PI Lin has strong expertise in membrane-based water and wastewater treatment. Close collaboration will ensure fruitful findings from this one-year project.
The collaborative effort will lead to an effective and practical solution to decontaminate IDW at DoD sites with minimal energy cost and space requirement. Results from this project will also provide fundamental understanding on (1) mechanisms of PFAS transformation and defluorination by sequential oxidation and reduction strategies, (2) process design rationales for the integration of multiple modules for optimized contaminant treatment in complex IDW matrix, and (3) fate of PFASs in the engineering treatment train. Knowledge can be transferred to a broad scope of water/wastewater treatment. Results from this project are expected to initiate an Environmental Security Technology Certification Program (ESTCP) project. (Anticipated Completion - June 2019)