Brief Summary of Minutes of Annual Meeting

Reporting Period

10/1/2022 to 09/30/2023

Accomplishments

Objective #1-  Evaluate the short- and long-term fate, bioavailability and persistence of trace organic contaminants (TOrCs) with an emphasis on per- and polyfluoroalkyl substances (PFAS) and pathogens in residuals, reclaimed water, and amended soils to aid in assessing and minimizing environmental and human health risks from their application at a watershed scale. Specific tasks: i) Quantify and evaluate the uptake, accumulation and transport of TOrCs in residuals, wastewaters and residuals- and wastewater-treated soils (e.g., agricultural, urban and brownfields); ii) Predict the long-term bioavailability, persistence and toxicity of TOrCs in residuals- and wastewater-amended soils; iii) Evaluate ecological effects of TOrCs from soils amended with residuals and reclaimed wastewaters; and iv) Evaluate long-term effects of residuals and wastewater application on the emergence/spread of antibiotic resistance. Research for this objective was conducted by members from AZ, CA, FL, GA, KS, MN, OH, PA, WA.   

Per- and polyfluoroalkyl substances (PFAS)

PFAS analytes are perfluorinated compounds used in many household products to provide water- repellent and anti- stain properties. Because of their common usage, PFAS is ubiquitous and found in soil, water and sediments worldwide. They are also found in wastewater, and during wastewater treatment they partition into the solid phase and end up in biosolids. Because biosolids are land applied, there has been increasing concern over the potential for biosolid derived PFAS to leach through soil and the vadose zone, ultimately contaminating groundwater used as a potable water source.     

Researchers from several states performed laboratory and field studies to quantify the occurrence, persistence, fate, and human health effects of PFAS.

A national collaborative project led by researchers in AZ is currently evaluating the incidence and mobility of PFAS through soil following land application of biosolids. The project includes 30 land application sites across the US, with different soils, depths to groundwater, and variable climates. The team also measured PFAS concentrations in groundwater beneath the land application sites. Data from this project is expected to allow for validation of a screening level risk assessment model to predict the risk of PFAS leaching and subsequent groundwater contamination.

A literature review conducted by the GA team on the potential input of PFAS to soil from air, water, and landfill found that PFAS in air (average of 101-2 pg/m3) and landfill leachates (average of 100-2 ng/L) were the main sources of PFAS in soil. Many factors, such as solution pH and cations, influence sorption and desorption of PFAS in the water-soil interface. Similar work is also being conducted in NM. Investigators conducted a literature review and meta-analysis on the global distributions of PFAS substances in the environment.

Studies in GA characterized PFAS in fluorinated-industrial wastewater using liquid chromatography-high-resolution mass spectrometry and data-processing algorithms. Data demonstrated that a total of 175 formulae of PFASs were identified. In particular, 18 iodinated PFAA formulas involving 21 congeners were identified for the first time, indicating the possibility of forming iodinated PFAS in fluorination industrial wastewaters.

In MN, biosolids from 5 facilities were analyzed for a suite of PFAS compounds.  All biosolids tested were found to contain detectable levels of PFAS.  Similarly, PFAS in various forms were detected in most soil and lysimeter water samples, indicating that PFAS was already present at the site, even before biosolids were applied.  A new study will be initiated in 2024 to evaluate PFAS in three participating WWTPs and three farmers who have been applying biosolids on their cropland.

Multiple states are currently working on PFAS toxicity studies. For instance, researchers in FL examined trophic transfer of PFAS within a simulated terrestrial food chain (tomato à tobacco hornworm). Data indicated that while patterns of uptake and elimination were similar between different PFAS, PFOS bioaccumulated in the hornworms to a higher concentration, featuring approximately 5-fold higher assimilation efficiency than other PFAS tested.  Bioaccumulation and trophic transfer factors were positively correlated with PFAS carbon chain length for both sulfonates and carboxylic acids.  This result suggests that although recently published work has demonstrated that shorter chain PFAS are more readily accumulated in plants, shorter-chain PFAS may also be more readily eliminated by higher trophic level consumers.

In PA, a community-science based PFAS project to assess the occurrence of PFAS in rural water supplies was launched in collaboration with the Penn State Extension Master Well Owner Network. Nearly 115 homeowners participated in the study and collected water samples from their private wells. Results suggested that more than half (52%) of the 115 wells sampled have detectable levels of PFAS, such that 60 of the 115 wells had PFAS concentrations exceeding the EPA’s interim health advisories.

The PA team is also conducting an ongoing monitoring effort at the Penn State “Living Filter”, which has been spray-irrigating treated wastewater at the site for 40 years. Since October 2019, we have collected bi-monthly samples of the wastewater (influent and effluent) and the 13 groundwater monitoring wells at the site. Additionally, we are collecting crop tissue at the time of harvest for corn silage and haylage to determine the PFAS concentrations incorporated into animal feed. Results showed elevated levels of PFAS in the groundwater at the site, with concentrations of PFOA and PFOS above the EPA’s proposed drinking water standard 10 of the 13 monitoring wells and above the PA DEP’s MCLs in 7 wells. Data collected from the harvested corn silage and fescue suggest that PFAS (mostly short-chain compounds) are entering the food chain at a rate of between 2.45 and 7.48 mg/animal/year for dairy cattle. It is unknown what the impacts to livestock health and milk quality might be, and more information is needed to provide context for these numbers from other similar studies at wastewater-irrigated facilities.

Work in FL demonstrated that the use of Al, Ca and Fe DWTRs to immobilize and/or reduce the bioavailability of PFAS is effective, particularly for short chain PFAS, albeit at relatively high application rates (10% DWTR by mass application to biosolids). They also demonstrated that PFAS partition coefficients from 16 biosolids samples were highly variable (~10 to 20,000 L kg-1) and dependent on both PFAS and wastewater treatment process.

Research in GA evaluating the use of electrooxidation for destruction of PFAS in water indicated that surface fluorination of Ti4O7 anode can effectively mitigate the formation of chlorate and perchlorate when chloride is present in the wastewater, without significantly comprising the PFAS treatment performance. The team also studied the degradation of chloramphenicol by electrooxidation. A study on PFAS removal by foam fractionation (FF) indicated that higher air flow, greater ionic strength, and addition of thickener boosted PFAS removal in the defoamed bottom solutions and intensified enrichment in the collected foam. FF is potentially a technology that can be applied on large quantities of water in a cost-effective manner, which can remove PFAS from water and concentrate them in a small-volume foam solution. It can be further coupled with a PFAS destruction technology, such as electrooxidation, to destruct the concentrated PFAS in the foam solution, forming an FF-EO treatment train that can be an effective option to manage PFAS in wastewaters.

Pathogens and Metals

With current projections indicating an increase in the frequency and intensity of extreme weather events such as hurricanes, coastal regions, including the Texas Gulf Coast, are increasingly vulnerable to drinking and recreational water contamination caused by flooding. A study conducted in TX evaluated fecal indicator levels and bacterial communities in Clear Lake near Houston, TX following Hurricane Harvey. Fecal indicator bacteria levels were elevated immediately after the hurricane but decreased to below regulatory levels within one week. Likewise, the bacterial community shifted from being dominated by Cyanobacteria before flooding to being dominated by Proteobacteria and Bacteroidetes immediately after flooding and then returning to a community resembling pre-flooding conditions. A second study measured fecal indicator levels in private drinking water wells in the area around Houston, TX in the weeks following flooding from Hurricane Harvey. This information was used in quantitative microbial risk assessment to determine the increased risks from various exposure scenarios. It was estimated that median health risks exceeded USEPA’s daily risk threshold of 1x10^-6 for gastrointestinal infection with the greatest risk being from norovirus and Cryptosporidium. Smaller levels of risk were also associated with bathing and food preparation. Ongoing work is further characterizing residents’ behavior with respect to treating and maintaining their drinking water sources following flooding events.

Coronavirus, pharmaceuticals, and substance of abuse surveillance

A project funded by Penn State and the Pennsylvania Department of Health to continue the University’s wastewater surveillance program for SARS-CoV-2, pharmaceuticals, and influenza A and B. The surveillance efforts also include two other WWTPs in PA. The PA team ran data analysis tools through supercomputing facilities on campus to determine the doubling rate of each virus. The results were shared with facility operators within 48 hours of sample collection, enabling the communities to track increases and decreases in near-real time. These data have been utilized, along with other indicators, to understand the prevalence of the viruses within the community over the past year. The data have been particularly effective when they are showing decreasing trends, to provide reassurance that downward trends in individual case data are also true at the community scale.

Microplastics

Microplastic particles (size of 1 μm - 5 mm) are a contaminant of emerging concern in wastewater and biosolids. Research in CA focused on the development of microplastics sampling, analysis methodologies (including the development of new spectroscopic software for the chemical characterization of microplastics), monitoring of microplastics in rivers, streams, and coastal marine habitats, and advancement of the scientific understanding of microplastics transport in streamflow and sediments. Collaborators include the Southern California Coastal Water Research Project, the Santa Ana Regional Water Quality Control Board, Orange County Sanitation District, Orange County Environmental Resources, and the Los Angeles County Department of Public Works.

Other unregulated organic contaminants

Research in OH was focused on the prioritization of UOCs in biosolids being amended to soil based on their occurrence, mobility, persistence, bioaccumulation, and potential toxicity to humans. The prioritization study leveraged empirical and modeled data for use in a scoring scheme to derive a short list of UOCs of greatest potential concern for offsite transport, bioaccumulation, and toxicity. The major challenge is identifying UOCs that are most likely to be mobility and bioaccumulation in the environment and the effects of these compounds on human health. While information is easily accessible either by measurement or predictive modeling, there is a lack of a methodology to perform high throughput screening of UOCs. The priority list serves as a starting point to perform laboratory and field experiments for those chemicals with the highest risk to human health. The starting list of biosolids-borne chemicals of potential concern was prepared from the USEPA biennial reports, TSSS survey, USEPA CompTox dashboard, and literature. From this database of 912 chemicals, data filtering resulted in 128 UOCs of high concern. These UOCs were then ranked via a scoring scheme based on the following parameters: (1) occurrence, (2) mobility, (3) persistence, (4) bioaccumulation, and (5) toxicity. The assessments simulated were: (1) mobility and persistence, (2) mobility and bioaccumulation, (3) persistence, bioaccumulation, and toxicity, (4) mobility, bioaccumulation, and persistence, and (5) mobility, persistence, bioaccumulation, and toxicity. Based on these assessments, some of the highest priority UOCs included Desmosterol, Triphenyltin, Aroclor 1254, Digoxin, and N-Nitrosodimethylamine, Polyethylene terephthalate, Dimethyl sulfone, Clinafloxacin, and Digoxin.

Treated wastewater is a critical and valuable water source to augment agricultural irrigation, especially in arid and semi-arid regions. However, recycled water irrigation introduces many trace organic contaminants (TOrCs) into agroecosystems, and concerns about the potential accumulation of TOrCs in food produce hinder its broader adoption. Fundamental and applied research in CA funded through USDA and EPA evaluated processes and risks of TOrCs in the wastewater-soil-plant continuum. Findings suggested that plant accumulation of TOrCs depends closely on the specific compounds, and that potential accumulation in edible parts is generally low for many TOrCs when treated wastewater is used for irrigation. In addition, plants possess the capability of quickly metabolizing many TOrCs via conjugation, which contributes to a reduced translocation and accumulation in edible organs. The CA team also evaluated a simple and yet practical mitigation strategy to further minimize accumulation of TOrCs in plants – alternating sources of irrigation water, by using treated wastewater only for the first half of the growing season.

Objective 2: Objective 2 of the project: Evaluate and optimize the uses and associated environmental benefits of residuals and wastewaters applied to various ecosystems (e.g., agricultural, urban, recreational, forest, rangeland, mine-impacted, other anthropogenic) on soil physical, chemical, and biological properties and plant nutrition, health, and yield. Specific tasks: i) Quantify the effects of biosolids and other municipal, industrial, and agricultural residuals on indicators of soil health; ii) Quantify the effects of biosolids and other residuals on pollutant (TOrCs and metals/metalloids) availability, assimilation, phytotoxicity, and remediations. Research on this topic was conducted by members from AZ, CO, FL, HI, KS, NE, OH, PA, , WA

Soil health and soil carbon benefits

Land application of biosolids has been associated with multiple agronomic and environmental benefits; however, the intimate association between biosolids use and soil health has not been adequately addressed. Research in CO continues to demonstrate soil health benefits associated with long-term land application of biosolids to agroecosystem. Results demonstrated that biosolids application at agronomic rates has greater, positive impact on soil health than inorganic fertilizer. These findings help assure that biosolids land application in the western US is a positive attribute for municipalities with land application programs. The CO team has also partnered with the Soil Health Institute, and Washington State University to further evaluate soil health in long-term agroecosystem research plots. Results from this effort indicated that biosolids increases long-term soil C accumulation with subsequent positive impacts on soil health. Research is also focused on evaluating the potential impacts of biosolids on soil microbial community function and structure. Research in CO also demonstrated that biosolids application (rates of 10 Mg ha^-1) to overgrazed, western US rangelands improves soil health without negatively compromising above-ground plant community structure/function.

Collaborative research among CO, OH, and WA continues to evaluate biosolids land application in mine land contaminated with heavy metals, with a specific focus on soil health and plant health. Results showed that although biosolids can improve mine land soil health and reduce plant-available heavy metals, above-ground plant tissue metal concentrations still may be greater than acceptable for browsing animals. The research team is working towards including soil heavy metal concentrations into an overall soil health program.

Water quality

Research in KY demonstrated that biosolids- decreased expression of several genes in the denitrification/nitrification pathways. Overall, results from the metatranscriptomic analysis support many benefits of biosolids application to soil that pertain to the N cycle: (i) decreased production of leachable NO2- and NO3-, (ii) increased production and assimilation of NH4+ into soil organic matter, and (iii) reduced emissions of the greenhouse gas, N2O.

A field study in FL evaluated the impacts of new state biosolids rule (62-640, Florida Administrative Code) on crop performance, soil health, and water quality responses. Results demonstrated significant lower risk of nitrogen and phosphorus losses via leaching than commercial inorganic fertilizer. Data also demonstrated significant agronomic benefits associated with biosolids application to pastures. Reduced (P-based) biosolids application rates may not be practical or economically feasible for farmers, which will result in the loss of a valuable resource that can have many agronomic and environmental benefits .

A mesocosm study in PA  is investigating the potential benefits of organic matter amendments to a stormwater bioretention cell for improving nitrogen removal. The study also investigated the potential impact of de-icing agents on denitrification in the bioretention cell. Total nitrogen removal was found to be positive for most treatments, indicating net removal in the stormwater bioretention mesocosm experiment. However, negative removal efficiencies, or nitrogen leaching, was observed for some treatments and sampling events, almost exclusively for free-draining mesocosms. These preliminary results support the value of saturated zones and carbon amendments in bioretention soils to assist with improved N treatment. 

Biochar studies

Researchers in NE are investigating the effects of biochar soil carbon sequestration, greenhouse gas emissions, and nitrate retention. One of the key findings was that the redox driven formation of iron oxides on surfaces of biochar aging in soil can explain the improved retention of nitrate in biochar amended soil. Biochar also resulted in significant increases in soil carbon storage in 0-30 cm depth, six months after application of biochar. Additional benefits from synergistic effects of cover cropping and biochar on soil carbon storage seem to take longer to be detectable. The data emphasize the potential of biochar application in combination with cover crop  to increase resource efficiency in corn-soybean systems but also highlight the need for long-term data from different sites to make recommendations for reduced N-fertilization rates, for example.

Research in PA  evaluated the effectiveness of biochar produced from two feedstocks (cotton gin waste and walnut shells) to remove four pharmaceuticals from aqueous solution. Biochar produced from cotton gin waste was able to effectively remove docusate, whereas the walnut shell biochar removed acetaminophen and sulfapyridine better than the cotton gin biochar. Both biochars removed ibuprofen at similar efficiencies. The team is currently evaluating three pre-treatment options to improve performance of the biochar.

Beneficial reuse of manure and other organic residuals

Research in FL examined how different soil nutrient tests correlate with various lead bioavailability tests in a variety of lead contaminated soils, including those receiving lead-immobilizing amendments such as compost Results indicated that a diverse suite of relatively inexpensive and accessible soil nutrient test methods correlate with bioaccessible Pb at a specific site, regardless of whether Pb-immobilizing amendments have been used.

A study in HI evaluated P availability and Al and Mn toxicity following application of three P sources (Kailua biosolids, chicken manure, and cowpea green manure) to two highly weathered, acidic Oxisols of Hawaii. Results demonstrated that all three organic amendments reduced soil P sorption, and chicken manure was the most effective in keeping more P in the soil solution. Soybean growth and P uptake varied depending on the P source and soil type.

Research in NE demonstrated that manure in conjunction with inorganic fertilizer and woodchips did not affect crop growth and yield.

Urban soils

Use of biosolids and other residuals- based amendments in proximity of the areas where they are generated offers multiple benefits. It increases public awareness and also provide a cost- effective end use for residuals- based products. For the end uses, residuals- based amendments are likely to show equal benefits, if not more extensive benefits with urban use in comparison to more traditional agronomic end uses. Promoting urban use of residuals closes an important loop for nutrient recycling and provides an opportunity for food production in urban areas. Research in WA evaluated the potential for urban residuals use and nutrient cycling in the context of urban agriculture. Results demonstrated that crop yield in disturbed urban soils was significantly greater than with fertilizer for all of the products tested. The team also calculated nutrient flows through food scraps and wastewater in Seattle and Tacoma. Wastewater had much higher N and P flows than food scraps. While a majority of the P was captured in the biosolids, the majority of N in the system was released in the effluent.

Anthropogenic activities have left a legacy of contaminated vacant land which disproportionately affects lower income communities and can have detrimental impacts on human health, particularly children. EPA estimates that 95% of children will ingest 200 mg soil/day which places children in close proximity to contaminated soil at increased risk of ingesting Pb. The national average blood lead level (BLL) in children is 1.2 µg/dL with excessive BLL threshold of 5 µg/dL. However, 13% of children in Cuyahoga County, Ohio and 17% of children in Cleveland, OH have BLL > 5 µg/dL. Research in OH evaluated the impact of exposure to soils with legacy contamination, including lead, arsenic and other heavy metals, to urban populations. Remedial action has been slow in contaminated communities. Excavation and replacement of contaminated soil is destructive and expensive. Soil testing to identify contaminated soil is either prohibited and/or expensive. The result is continued unacceptable exposure of legacy contaminants such as lead. The OH team developed  a novel risk management approach where enhanced soil amendments is used as reactive topsoil to reduce heavy metal contaminant bioavailability and exposure and provide a physical barrier. Reactive topsoils were created from locally available byproducts: biosolids incineration ash, Lake Erie dredge, biosolids compost, and yard waste compost. Four soils blends of varying combinations of the above byproducts were mixed with the top 10 cm of contaminated residential soil. The soil blends were seeded with a native plant mixture selected for residential ecological restoration. Potential lead exposure to humans, from soil or dust ingestion, was determined by measuring in vitro Pb bioaccessibility (IVBA Pb) using U.S. EPA Method 1340. Soil blends were very effective in reducing IVBA Pb up to 50%.  Reduction of IVBA Pb  was attributed to reactive Fe and Al oxides from biosolid incineration ash. Topsoil blends can provide a physical barrier and a chemical barrier when applied to vacant urban land. Reactive additives, that adsorb or precipitate contaminants, will reduce exposure from future aerial deposition of Pb and other legacy toxicants in urban areas.