PFAS, also known as “forever chemicals”, are listed as persistent organic pollutants (POPs) under the Stockholm Convention, due to their ubiquity, persistence, toxicity, and bio-accumulative nature in the environment. This persistence has led to the bioaccumulation of PFAS in biota, aquatic and land

life as well as humans. Since their genesis in the 1940s, PFAS have been detected in the ambient environment, wildlife, and human serum around the globe.

Due to the widespread presence of PFAS in the environment, its unusual chemical properties, the uncertainties associated with its potential risks, and the resulting need for a precautionary approach to protect the environment and human health, the environmental management of PFAS is a high priority for environmental regulators around the world.

Yes. To date, a total of two (2) ‘real world’ field-scale studies have been undertaken on the Opus Filter. The studies were undertaken in Western Sydney, NSW, Australia and are documented in the following published journal paper:

Dalrymple B, Allingham B, Wicks M, Jones W, McDonald J, 2023, Per and poly-fluoroalkyl substance (PFAS) removal by a radial flow cartridge system, Australian Water Association Journal, ISSN 2206-1991, Volume 9 No 4 2023, doi.org/10.21139/wej.2023.013

Two (2) ‘real world’ field-scale studies of the Opus Filter technology have demonstrated high removal rates of PFAS from PFAS contaminated surface water. Results from the first field study demonstrate a PFAS removal of 87% (at a mean influent concentration of 1.43 µg/L) for a total load removal of 0.34 grams during the peak performance period – after which replacement of the Opus Filter media would likely be recommended to ensure high PFAS removal rates for a single Opus Filter. Results from the second field study which, incorporated pre-treatment of PFAS contaminated water using a Jellyfish membrane cartridge technology (prior to subsequent treatment by an Opus Filter technology) demonstrate a PFAS removal of 93% (at a mean influent concentration of 66.6µg/L) for a total load removal of 2.01 grams of PFAS removed during the peak performance period.

To achieve high PFAS removal rates (and/ or lower concentrations in discharged waters) Opus Filter technologies would need to be placed ‘in series’ to provide a multiple pass treatment system. Given the small footprint of the given Opus Filter (diameter of 550mm for the ‘small’ 360 cartridge), the integration of Opus Filter technologies in series should be practical at many sites. Alternatively (or in addition to an ‘in series’ system), the Opus Filter is commercially available as a larger 690 system with approximately 50% more media volume, which would further augment higher PFAS removal rates.

Yes. We typically recommend that Opus Filter technologies be applied as part of a stormwater ‘treatment train’, typically with pre-treatment technologies integrated upstream, such as ‘gross pollutant traps’, ‘gully pit inserts’ and/ or the Jellyfish® membrane cartridge system. These additional/ upstream stormwater treatment assets act to augment the treatment performance of the overall system by removing pollutants such as litter, particulate matter, organics and associated pollutants (e.g. heavy metals, nutrients).

These devices are unlikely to remove PFAS, but will likely augment the performance of Opus Filter by removing pollutants (e.g. solids, organic carbon) that that may be otherwise adsorbed to the Opus Filter media in preference to PFAS and subsequently reduce the PFAS removal and/ or longevity of the Opus Filter system.

This depends on the extent of PFAS contamination in the applied media cartridges. Consistent with Opus Filter Operation and Maintenance Guidelines, samples of the membrane and/ or media are analysed in a laboratory. These analyses determine how the used technologies are to be disposed.

It is anticipated that the contamination levels will likely be sufficiently low to permit disposal in an appropriate landfill facility (following appropriately handling, consistent with the aforementioned guidelines). To reduce any handling and/ or contamination risks, the entire cartridge(s) (which house the absorbent filter media) are removed and (for ongoing applications) replaced with new cartridges.

The ‘peak performance period’ is the period of operation where the Opus Filter (and/ or ‘treatment train’ if pre-treatment is present) when PFAs removal is optimal, and after which replacement of the Opus Filter media would likely be recommended to ensure high PFAS removal rates. The frequency of this media replacement is dependent on site characteristics – particularly, the PFAS loads discharged to the Opus Filter technologies. This is evidenced by the difference peak performance period between two field studies by Dalrymple et al (2023), which demonstrated that the peak performance period for the Opus Filter in the two field studies was 4,800 and 467 bed volumes for study 1 and 2 respectively, which would be largely due to the difference in influent PFAS concentrations (mean of 1.43 and 66.64 µg/L for study 1 and 2 respectively. It is subsequently anticipated that performance monitoring may be required to determine the peak performance period for the system.

Operation and Maintenance Guidelines and Safe Work Method Statement documentation has been prepared by independent consultants (Optimal Stormwater) who are recognised as industry leaders in the appropriate maintenance/ management of stormwater treatment assets. This documentation includes several actions to help protect the health and safety of any individuals associated with the maintenance/ management of these technologies.

Yes.

A single standard 460 Opus Filter cartridge has a treatment flow rate (TFR) 0.46 litres per second per cartridge. The TFR of our ‘taller’ 690 cartridge is 0.90 litres per second per cartridge.

Many individual cartridges can be included in any single application.

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