The objective of this Statement of Need (SON) was to develop an improved understanding on how different waste stream characteristics and physical and biogeochemical conditions affect the efficiency and effectiveness of per- and polyfluoroalkyl substance (PFAS) destruction in non-thermal destructive treatment processes. Specific objectives of this SON included the following:

• Evaluate how different waste streams – with varying electrolyte composition, ranges of PFAS (precursors to byproducts), and common co-occurring chemicals of concern – impact technology functionality and treatment effectiveness.
• Develop a fundamental or holistic understanding of how destructive treatment technologies function for a variety of PFAS-impacted sources including aqueous streams, soils and sediments, and concentrates (e.g., aqueous film-forming foam [AFFF], reject water, regenerants, still bottoms).
• Evaluate how soil properties and pH impact treatment effectiveness.
• Evaluate how geologic permeability and hydrology impact treatment effectiveness and efficiency.
• Identify indicators of operational and treatment success and assess how they can be leveraged to improve treatment efficiency and avoid unintended consequences.
• Identify the range of applicability and limitations of the technology as well as where it may fit into a treatment train.

Proposals could have addressed one or more of the objectives listed above. Proposers were directed to review the document Summary Report: Strategic Workshop on Management of PFAS in the Environment for additional information on these research objectives. This document provides a summary of the March 2022 strategic workshop on PFAS in which research and demonstration needs were identified so as to improve the management and treatment of PFAS in the environment, ultimately reducing risk and site management costs.

Researchers had to provide the rationale for selected PFAS of study; at a minimum, measurement of the 40 PFAS that can currently be measured by U.S. EPA Method 1633 should be prioritized as possible. Treatment of PFAS at environmentally relevant concentrations is of particular concern, and proposed efforts should have reflected this concern or provided the rationale if different concentrations were proposed.

Research and development activities at laboratory-, bench-, and field-scale were considered, although work did not necessarily have to culminate in a field-scale effort.

Research should lead to improved management of PFAS sites by facilitating the establishment of more cost-effective and efficient remedial action plans that are protective of human health and the environment. The improved remediation approaches that will be developed through this SON will increase the reliability of treatment processes and expedite the cleanup and closure of Department of Defense (DoD) impacted sites.

Numerous treatment technologies for the destruction of PFAS have been and are currently being developed for a variety of PFAS-impacted matrices. These technologies are at varying stages of development ranging from bench-scale (e.g., microcosms, columns, single reactors) to field-scale units (e.g., mobile treatment trailers, packed bed systems, etc.). Many of these technologies have proven to destroy PFAS, but primarily in the laboratory and under a limited set of conditions.

To move these technologies forward to larger scales, additional research is needed. Laboratory and pilot-scale studies conducted under a range of solution and geologic conditions will aid in identifying which technologies are best suited for a full field demonstration alone or as part of a treatment train. Data collected in these studies will also identify parameters within those technologies that can be optimized to allow more effective and efficient treatment at the field scale. Technology evaluations and their role within a treatment train need to include quantifying fluorine mole balances and consider formation of secondary byproducts (e.g., perchlorate, chlorate), ease of implementation, technical and economic scalability, and energy requirements.

In addition, it is critical to gain a fundamental or holistic understanding of how these technologies function for a variety of PFAS-impacted sources including i) aqueous streams (groundwater, surface water), ii) soils and sediments, and iii) concentrates (AFFF, reject water, regenerants, and still bottoms). By using consistent sources of PFAS-impacted matrices to test these technologies, comparison of treatment technologies will be more effective. The benefits of this approach include facilitation of greater inclusivity of new technologies, avoiding hurdles related to site access, and avoiding inconsistencies between comparisons due to different sources.

The cost and time to meet the requirements of this SON were at the discretion of the proposer. Proposers submitting a Standard Proposal had to provide the rationale for this scale. The two options were as follows:

Standard Proposals: These proposals describe a complete research effort. The proposer should incorporate the appropriate time, schedule, and cost requirements to accomplish the scope of work proposed. SERDP projects normally run from two to five years in length and vary considerably in cost consistent with the scope of the effort. It is expected that most proposals will fall into this category.

Limited Scope Proposals: Proposers with innovative approaches to the SON that entail high technical risk or have minimal supporting data may submit a Limited Scope Proposal for funding up to $250,000 and approximately one year in duration. Such proposals may be eligible for follow-on funding if they result in a successful initial project. The objective of these proposals should be to acquire the data necessary to demonstrate proof-of-concept or reduction of risk that will lead to development of a future Standard Proposal. Proposers should submit Limited Scope Proposals in accordance with the SERDP Core Solicitation instructions and deadlines.