Development of Smart Flocculants for the Treatment of PFAS Contaminated Water

Project Summary Per- and polyfluoroalkyl substances (PFAS) are a family of manmade congeners with dual hydro- and oleo- phobic properties, which is why they have been widely used in firefighting foams, as well as in a multitude of other products such as food packaging, paints, pesticides, and microelectronics. Given their extensive use, high water solubility, and resistance to conventional wastewater treatment methods, PFAS have been detected in public water supplies all over the country causing concern for potential toxic human health effects given their environmental persistence. Flocculation is a widely used separation technique in the removal of suspended solids from water and wastewater. However, traditional flocculants (e.g., inorganic salts and polymeric systems) form aggregate flocs that are usually loosely packed, contain a large amount of water due to their hydrophilicity and as such, require large settling tanks due to the slow process of separation that is required to collect the solids. Furthermore, they have seldom been used to remove dissolved species like PFAS. To address these issues, BAM has developed EnviroFloc: an innovative “smart” polymeric flocculant that consists of a temperature responsive compound, N-isopropylacrylamide (NIPAAm), modified with cationic co-monomers and/or fluorinated co-monomers. The combination of these three components results in a polymer which can rapidly capture the dissolved PFAS molecules and form insoluble solid aggregates at temperatures above the lower critical solution temperature (LCST) The core advantages of this system include: (1) Low water retention in the sedimented floc: dissolved PFAS molecules are captured by the dissolved polymer at ambient temperature and then collected into an insoluble densely packed solid pellet above the transition temperature resulting in a smaller solid waste stream compared to other remediation technologies. (2) Fast kinetics, flocculation occurs within seconds to minutes as compared to several hours for other flocculant systems. (3) Relatively low energy input required to flocculate given EnviroFloc’s LCST being close to ambient temperature. (4) Little-to-no pretreatment needed of the contaminated stream when applied as secondary treatment for challenging PFAS wastes, RO concentrate, and IX brine. More specifically, aim 1 focuses on the development of EnviroFloc polymer flocculants for optimized flocculation performance. Specific Aim 2 will evaluate EnviroFloc regeneration via temperature assisted solid-liquid extraction to determine removal efficiency and EnviroFloc reusability, and specific Aim 3 will demonstrate EnviroFloc performance efficiency as a secondary treatment step in multiple case studies (e.g., RO concentrates and IX brine). Finally, specific Aim 4 will design, simulate, and demonstrate feasibility of a PFAS treatment unit. This Phase II SBIR project will accomplish the key tasks necessary to prepare for commercialization of BAM’s EnviroFloc and the associated treatment unit specifically for PFAS water treatment.