The objective of this Statement of Need (SON) was to seek fundamental or applied research to further understand the fate, transport, and treatment of microplastics in the environment impacted with per-and polyfluoroalkyl substances (PFAS) or other chemicals of concern (COCs). An improved understanding of fate and transport properties of microplastics in surface water, stormwater, soil, sediment, and groundwater was of particular interest, along with the fundamental understanding of the underlying mechanisms associated with removal and treatment, either via chemical, physical, or microbial processes, in order to develop cost-effective remedial technologies. Specific objectives included:

• Develop improved analytical methods for detecting and quantifying microplastics in environmental samples, as well as to detect and quantify COCs sorbed to microplastics in environmental samples. 
• Improve the fundamental understanding of fate and transport processes of microplastics in surface water, stormwater, soil, sediment, and groundwater under varying natural and engineered conditions.
• Determine the impact of sorbed COCs on both the fate and transport of microplastics and the COCs with emphasis on mechanistic processes.
• Improve understanding of the degradation process of microplastics in the environment, including the evaluation of environmental factors and physical and chemical composition characteristics that may affect degradation rates.
• Develop remedial strategies for microplastics with sorbed COCs, such as PFAS, including a systematic assessment of the necessity for treatment train approaches.

One or more of the objectives listed above could be addressed in a single proposal. Environmentally relevant concentrations of COCs was of particular concern, and proposed efforts should include such an assessment or provide the rationale if different concentrations are 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. Proposed in situ technologies and approaches could be applicable to a variety of hydrogeologic settings, including complex geology such as fractured bedrock aquifers. 

Addressing the research needs described above will provide a better understanding of potential impacts of microplastics with sorbed COCs and how these systems can best be treated, leading to improved site management that is protective of human and ecological health.

Microplastics have been found to enter the environment in a number of ways, including from landfill leachate, aerial deposition, stormwater, wastewater effluent, or direct impact from synthetic textiles. Such microplastics can also sorb COCs such as PFAS, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and chlorinated solvents. In order to fully understand the impact of these materials on site management, additional information is needed regarding the fate and transport of these materials, as well as potential treatment options. 

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.