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PFAS; Sustainability;

What is Kennedy Jenks bringing to UPM 2023? A new pilot in the PFAS destruction landscape

A discussion of the pros and cons of various PFAS destruction technologies, with Charlie Liu, National PFAS Lead at Kennedy Jenks Consultants

With incoming stringent regulations in the EU and the US aimed at cracking down on the discharge of per-and poly-fluoroalkyl substances (PFAS), the semiconductor industry finds itself exploring the realm of PFAS destruction technologies.
Although several market players are commercializing PFAS destruction technologies, at UPM 2023, Kennedy Jenks Consultants will present information on a pilot for one of the lesser-explored methods – Reductive Defluorination (RD) with UV-Sulfite for PFAS degradation – with transparent data on the benefits and drawbacks of this technology as it sits in the landscape of PFAS destruction technologies.  
Several additional technologies being evaluated for PFAS destruction are electrochemical oxidation (EO), supercritical water oxidation (SCWO), and hydrothermal alkaline treatment (HALT). Each method has its benefits and drawbacks. For example, SCWO and HALT require high temperatures and pressures but can destroy PFAS in a matter of seconds to minutes. Although EO and RD can operate at ambient temperatures and pressures, treatment time is longer on the order of hours. Charlie Liu, National PFAS Lead at Kennedy Jenks Consultants told UPM ‘All these examples are generally energy intensive. PFAS are termed ‘forever chemicals’ for a reason – they are extremely difficult to degrade.’ Existing methods can also be energy intensive and require chemical addition. For instance, SCWO requires the addition of a co-fuel to keep the reactor temperatures high, while HALT requires substantial quantities of sodium hydroxide.
One drawback that all these technologies have in common is the necessity of specialist equipment. Kennedy Jenks undertook a pilot to demonstrate the potential of a method which could be an outlier to this rule. By concentrating waste streams with either reverse osmosis (RO) or nanofiltration (NF) membranes followed by UV-sulfite destruction, the pilot only used components which are widely commercially available, such as UV lamps and reactors. Sulfite is also a relatively easily accessible chemical on the market. In times of prevailing supply chain bottlenecks and limited resource availability, these methods could prove useful for mitigating PFAS-containing waste streams. 
The concept of concentration before destruction is one that market players are generally adopting to obtain more cost-effective destruction. In the case of the UV-sulfite methods, operators can also use reactors with a smaller footprint when treating more concentrated streams. The data for this pilot will show comparative evidence for both the NF and RO stage before the destruction step. Results showed that although NF offered a lower energy consumption, it rejects long-chain PFAS better than short-chain PFAS. At UPM 2023, Kennedy Jenks will report a comparison on the use of both NF and RO in this pilot, as well as transparent data on the energy and chemical consumption of the overall method. 
One key conclusion was that the treatment process is not currently continuous, as it takes several hours to perform the complete destruction (which is considerably longer than some of the other emerging PFAS destruction technologies). However, it is possible to consider solutions to render the process more continuous, which might involve adding additional separation processes such as foam fractionation or ion exchange after the RO stage. As such, the method is subject to continued research and exploration.


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