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PFAS Removal From Water With MIEX® Technology

Wednesday, December 1, 2021

image of MIEX resin for PFAS removal*This paper is authored by Craig Smith & Matt Raymond of Ixom Operations Pty Ltd and was originally presented in April 2020. The entire paper is available for download below.

 

PFAS Background

Per and Polyfluorinated alkyl Substances (PFAS) have been identified internationally as a serious environmental and human health risk issue of concern. Extremely low permissible safe concentrations have been established by the USEPA, for the specific regulated PFAS including PFOS/PFHxS), at 70 ng/l and for PFOA 560 ng/l, and these have been applied and largely accepted internationally for drinking water.

These PFAS are predominantly associated with soil and groundwater contamination at airports, military airfields, and fire training locations, where PFAS containing fire retardant chemicals have been historically used for decades in fire training. However, there are also situations where surface waters have also been contaminated from industrial runoff and other contamination mechanisms. The use of these PFAS containing chemicals has since been discontinued, however residual PFAS persisting in these locations have leached into soil and groundwater and have become mobilized and are creating environmental and human health exposure concerns.

 

MIEX® Background & PFAS Removal Evaluation

MIEX® resin is currently used worldwide in the treatment of water to remove anionic dissolved organics (DOC), colour and precursors to disinfection by-products. Anion exchange resins have been shown in research to be useful in removal of PFAS, and are commercially supplied for this application, with various manufacturers offering ion exchange resins for this purpose. These resins are used in fixed ion exchange bed configurations, and in many cases not regenerated, as normally applied for conventional ion exchange systems, but are run to exhaustion and then disposed of.

MIEX® resin has been evaluated and shown as being capable of efficient removing of over 99% of a range of PFAS and appears to have significant potential as an alternative technology for removal and management of PFAS contamination in groundwater, as well as surface water.

Preliminary research and laboratory scale evaluations undertaken of the use of MIEX® resins for removal of PFAS from a contaminated water sample in 2018, proved very encouraging initially with >99% removal of several PFAS species being achieved in early results. (see Fig 1 below)

 

graph showing PFAS removal rates using MIEX technology

 

Research and literature reviews undertaken have indicated that anion exchange resins have been developed and proven as suitable technology and are currently being used already for PFC removal. However, in most cases this is simply run to exhaustion and disposed of as a waste, necessitating stockpiling and/or incineration or other destruction methods to be undertaken for the contaminated resin waste. This is similar to the way in which GAC is used for PFC removal which is one of the already accepted technologies in use.

 

MIEX® technology has several potential technical advantages over fixed bed ion exchange systems currently used:
  • MIEX® operates in a fluidised bed contactor system, where resin is suspended and mixed with inflow water being treated. This means it is relatively insensitive to suspended solids, which will quickly block a fixed bed ion exchange bed.
  • MIEX® is a very small bead, typically 160-220 um in diameter so has very high surface area and adsorption kinetics within the fluidised bed contactor.
  • MIEX® technology continuously regenerates the resin in a side stream unit operation, and can potentially provide unlimited adsorption capacity.

 

Encouraging results obtained for the preliminary testing undertaken for removal of PFAS from water using MIEX® resin has led to a more intensive program of research and investigation of the potential for MIEX® to be used as a commercial option for PFAS removal. To further evaluate the effectiveness of MIEX® resin in terms of PFAS removal from contaminated water additional work has been conducted with universities who have access to specialized analytical equipment necessary for PFAS analysis.

 

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  and read the rest of this white paper.

 

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