Implementing the Defluorinator
Fig.1. PFAS-contaminated water is introduced to a saline solution (below 0.8 M) with live P. Putida, where it is degraded by enzymatic reactions (sped up with the assistance of mechanical fragmentation).
The Defluorinator is a scalable and cost-efficient system designed to limit the exposure of free floating PFAS from surface runoff in drinking water systems. This system is designed for facilities that frequently dispose of PFAS-contaminated liquids to prevent additional runoff at minimal costs compared to alternative techniques such as reverse osmosis and pyrolysis. The Defluorinator is composed of a cylindrical polyethylene case containing P. Putida with the enzymes haloacid and fluoroacetate dehalogenase. The bacteria is isolated in a solution of water contaminated with PFAS and saline water, the degradation of PFAS assisted by mechanical fragmentation of the bacteria. Over a span of 50 hours, P. Putida produces fluoride ions and hydrofluoric acid as a byproduct of its enzymatic reactions with PFAS mentioned above. Filters 1 and 2 (Fig.1) are composed of an open pore structure coated with an additional layer of sodium bicarbonate, eliminating the risk of a hydrofluoric acid contamination. Furthermore, activated carbon filters surround both filters of the Defluorinator, preventing the passage of fluoride ions through the microfiltration membranes. The open pores of the microfiltration membranes are designed to permit the flow of water into additional tubing attached to the system, allowing for the filtration of PFAS contaminated fluids before merging with the municipal water system.
In military bases such as Camp Pendleton, the Defluorinator can be manually connected to the underground water system of that respective base, filtering PFAS out of the water before that water inevitably enters the municipal water system. Despite the chlorine-based treatment in municipal systems, free-floating PFAS are not affected in the disinfection of that water supply, and thus require prior filtration before being introduced into the municipal water system. The Defluorinator runs in 50 hour cycles, requiring manual cycling of the P. Putida in the device. The requirement of manual cycling every 50 hours enables effective management of waste water by limiting disposal of excess water (that may otherwise not be contaminated by PFAS). Furthermore, it eliminates the possible endangerment of the water system of a military base by eliminating the possibility of unknown damage to the casing or filters of the defluorinator. The management of the Defluorinator, in the example of Camp Pendleton, would be conducted by the US army corps of engineers. The members of the corps of engineers would cycle the Defluorinator system once every 2 days, requiring the insertion of inactive P. Putida into the case of the Defluorinator. Major challenges of this system, however, lie in its dependency of manual operation. While filtration is autonomous, active pseudomonas must be cycled every 50 hours to maximize efficiency of the system. While the cycling process requires a small start-up time, the system requires a continuous startup, resulting in a minor time skew in the management of general facilities (in contrast to treatments such as reverse osmosis). The greatest skew in the effectiveness of the Defluorinator lies in the substantial time it takes to degrade PFAS, resulting in its limited applicability to isolated water systems, too slow to function effectively in municipal water systems. Its high cost-efficiency, however, promotes its usage in facilities with separate water systems (such as Camp Pendleton) that contribute to the majority of PFAS found in municipal water systems.