The objective of this Statement of Need (SON) was to seek innovative research to develop cost effective remedial technologies for matrices impacted by per- and polyfluoroalkyl substances (PFAS) resulting from the use of aqueous film-forming foam (AFFF) formulations. Preference was for small-scale, proof-of-concept efforts, but larger research efforts will be considered with supporting rationale and demonstrated proof-of-concept. Proposed efforts focused on the following objectives:

• Develop cost effective treatment approaches for PFAS-impacted matrices, including but not limited to groundwater, surface water, stormwater, soils, aquatic sediments, spent media, and AFFF concentrate. Proposed approaches can be in situ or ex situ, and can be intended for small-scale, mobile treatment, or large-scale efforts.
• Develop cost effective approaches for complete destruction of PFAS bound onto spent media (e.g., granular activated carbon [GAC] and single-use ion exchange resins), regeneration of spent media, and treatment of associated ancillary waste streams.
• Evaluate treatment technologies using field-impacted media containing PFAS mixtures and common environmental treatment complications (e.g., water quality parameters, co-occurring chemicals of concern, etc.).
• Develop treatment train approaches that cost-effectively treat PFAS and facilitate treatment of co-occurring chemicals of concern. 

One or more of the objectives listed above was addressed in a single proposal. A strategic workshop on PFAS was held in 2022 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. Proposers were encouraged to review the document Summary Report: Strategic Workshop on Management of PFAS in the Environment for additional information on these research needs. Proposers had to be cognizant of previous SERDP- and Environmental Security Technology Certification Program (ESTCP)-funded efforts that focused on developing treatment approaches for PFAS-impacted matrices.

It was preferred that at a minimum, the 40 PFAS that can currently be measured by U.S. EPA Method 1633 was assessed; deviation from this list was accompanied by the rationale for such deviation. Treatment of matrices impacted by PFAS at environmentally relevant concentrations was of particular concern, and proposed efforts included such an assessment 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. In situ technologies and approaches were applicable to a variety of hydrogeologic settings, including complex geology such as fractured bedrock aquifers. 

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 remediation approaches that will be developed through this SON will improve the reliability of treatment processes and expedite the cleanup and closure of DoD impacted sites.

AFFF formulations have been used since the 1970s to suppress liquid fuel fires and there are many sites now impacted by PFAS. Due to their chemical structure, PFAS are very stable in the environment and are relatively resistant to biodegradation, photo-oxidation, direct photolysis, and hydrolysis. The perfluoroalkyl carboxylic acids and sulfonic acids have very low volatility due to their ionic nature and can leach from vadose zone sources into groundwater despite many operative soil retention processes. Further complicating the issue, many of the PFAS found in AFFF formulations are highly soluble and migrate rapidly, while others are far less mobile. The more soluble PFAS are likely to become depleted through flushing from source zones over time. However, other PFAS may be retained in the source zone, with varying degrees of potential for mass transfer into the aqueous phase, infiltration to groundwater (for vadose zone source areas), and/or groundwater migration into surface water, particularly after several years in the subsurface. perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are relatively mobile, though their fates are complicated by the presence of potential precursors for these compounds in complex PFAS mixtures. Effective treatment options are needed that address the variety of matrices that may be impacted by PFAS.

Granular activated carbon (GAC) is being used at several sites to specifically remove PFOS and PFOA from impacted water in ex situ systems; however, the cost-effectiveness over time of GAC systems remains questionable, specifically with regard to regeneration. Use of some types of technologies results in generation of ancillary waste streams (e.g., brines are generated during regeneration of ion exchange resins). Solutions are needed that include provisions for regeneration of spent media, and treatment and disposal of ancillary waste streams.

The cost and time to meet the requirements of this SON are at the discretion of the proposer. Proposers submitting a Standard or Limited Scope Proposal must provide the rationale for the proposed scale. The two options are 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.