STATEMENT OF ISSUES AND JUSTIFICATION

STATEMENT OF ISSUES:

Over 260 million tons of residual by-products, such as urban wastes (biosolids, recycled water, food scraps and other municipal solid waste), agricultural waste (manure), industrial sludges and waste byproducts (e.g., bioenergy residue byproducts) are currently produced in the U.S. (US EPA, 2018). According to the US EPA (2018), approximately 8.9, 12.8, and 25.8% of these materials are either composted, combusted for energy recovery or recycled, respectively, while the remaining 52.5% are landfilled. Specifically in terms of material disposal, ~50% of biosolids, 98% of food scraps and 45% of yard trimmings are currently landfilled or incinerated at a substantial cost to the industry and public (King et al., 2011). Thus, increasing reuse of various residual materials such as soil amendments offers the potential to replace disposal costs with beneficial agronomic and environmental uses. It is predicted that 52% of the world’s population will live in regions under water stress by 2050 (Schlosser et al., 2014), resulting in high demand for wastewater recycling and reuse for agricultural production. In addition, treated liquid wastes, such as wastewater effluent, recycled water and other non-potable waters, present opportunities for beneficial reuse in lieu of surface water discharge or expensive treatment. However, there are consistently numerous obstacles that prevent the full beneficial utilization of the above materials.

Obstacles that limit the beneficial use of residual products include conflicting regulations or the absence of regulations on residuals use, lack of public outreach and communication, and limited research on optimizing residuals-based product development. Fortunately, current and increasing evidence exits exemplifying that land application of a variety of residuals do provide agronomic and environmental benefits, which were either not previously well understood or are critical to addressing emerging environmental issues (e.g., system resiliency in the face of changing environmental factors highlighted in Brown et al., 2011). The W3170 workgroup, who consists of some of the best minds and resources within and outside the State Agricultural Experiment Station System (e.g., US EPA, municipality personnel, private entities), proposes to continue to conduct research towards sustainable use of residual products. The W3170 proposes to continue investigating the biogeochemical cycling of plant nutrients, movement and potential adverse impacts of trace element and trace organic contaminants (TOrCs) within ecosystems and the food chain, their long-term bioavailability in residual-amended soils, and soil health effects from application of residuals. These investigations will generate knowledge needed to develop and promote residuals recycling practices that are protective of human health and the environment. Outcomes will provide data for continuing one-health based risk assessment required by the US EPA Part 503 Rule for biosolids land-application as well as for developing regulations for land-based recycling of residuals and reclaimed water. Research will also focus on reuse benefits including field and watershed scale effects on soil quality/health, plant drought response, soil carbon sequestration, water quality, greenhouse gas emissions and climate change impacts associated with soil-based residuals and reclaimed water reuse. We will also explore the potential for residual based product usage in urban and agriculture systems, and green stormwater infrastructures as well in restoration of degraded lands. W3170 members are currently conducting and synthesizing both short- and long-term research that will enable the development of guidelines for the sustainable use of a wide variety of residuals and residual by-products: maximizing benefits while minimizing the potential for unintended negative consequences.

JUSTIFICATION:

The beneficial use of residuals requires an understanding of both potential hazards and the value of constituents in the by-products. Investigation of the fate and behavior of contaminants and nutrients in biosolids-amended soils has been the historic research focus of the W3170 multistate workgroup. Research conducted previously by the workgroup formed the basis for the U.S. EPA Part 503 biosolids rule, which is one of the few rules to include bioavailability assessments in the development of limits for critical contaminants (National Research Council, 2009). Two subsequent NAS reviews, focused on the 503 rule, confirmed that scientific basis for this rule and risk assessment were valid (NRC, 2002). Members of the W3170 group have contributed research and technical expertise that has led to guidance that permit beneficial reuse of many industrial and municipal byproduct for land application or as feedstocks in manufactured soil blends,  including spent foundry sands (U.S. EPA, 2014), water treatment waste residuals, and many other residuals (Ohio, EPA). Most recently, research conducted by W3170 members included evaluating the occurrence of per- and polyfluoroalkyl substances (PFAS), a large persistent class of TOrCs of high concern, in municipal solid waste composts (Choi et al., 2019). Their data contributed to the successful passage in 2018 of the State of Washington’s Healthy Food Packaging Act which bans the use of the entire class of PFAS in paper food packaging after January 1, 2022 assuming suitable alternatives are identified (HB2658-2017-18). This type of law will help prevent the use of products from other countries where PFAS-related bans may not exist and will prevent unwanted contaminants in our food, reduce their input into wastewater treatment plants, thus biosolids, and will minimize their entry into compostable materials where their presence has been pervasive.

This past year, the U.S. EPA Office of Inspector General released their report “EPA unable to assess the impact of hundreds of unregulated pollutants in land-applied biosolids on human health and the environment” (U.S. EPA, 2018). The U.S. EPA “identified 352 pollutants in biosolids but cannot yet consider these pollutants for further regulation due to either a lack of data or risk assessment tools. Pollutants found in biosolids can include pharmaceuticals, steroids, and flame retardants.” The W3170 committee is “the” USDA NIFA Multistate Committee that can continue to provide data and technical expertise to U.S. EPA for addressing the regulatory needs they identified in the U.S. EPA OIG report. U.S. EPA Office of Water and Office of Research and Development personnel continue to be active members of W3170.  Our university members are recognized internationally as leaders in research on the environmental fate of TOrCs, e.g, pharmaceuticals, steroids, chemicals from personal care products, flame-retardants and PFAS, that can be land-applied with biosolids applications.  Addressing U.S.EPA OIG data and research gaps will be a priority in the proposed W3170 renewed project.

Human and ecological risk assessment (HERA) science continues to mature with biogeochemical availability-based risk assessment frameworks being developed and/or considered for implementation in the U.S., Canada, the European Union, Australia and other countries. Continued research is needed to provide the scientific basis for risk-based methods and to evaluate residuals and residual-treated soils for adoption by HERA frameworks. Research needed to evaluate contaminants in residuals includes the following: (i) trace element speciation by advanced spectroscopic methods and wet chemical speciation methods; (ii) chemical lability and plant uptake potential of frequently detected trace elements and TOrCs in residuals-amended soils in the field; (iii) use of bioavailability to adjust human and ecological exposure in risk assessment frameworks by using inexpensive novel bioaccessibility methods and in vivo methods; and (iv) total combined effects of residuals on soil physical, chemical, nutrient and biological components in order to ascertain alterations in soil quality/health following residuals land application.

Several members of the W3170 were extensively involved in the development of the Part 503 regulation and continue to be involved in the development of risk assessment for other residuals (e.g., the EPA risk assessment for land application of cement kiln dust and foundry sand) and for other pollutants not initially regulated or considered in Part 503 (e.g., barium, TOrCs). The scientific approach used in the development of Part 503 has been applied by this group to an expanded variety of residuals, contaminants and receptors. As the understanding of bioavailability is expanding, the group is broadening its focus to develop linkages between quantitative understanding of the contaminant forms and their bioavailability to a range of receptors.

In the past, our group has conducted cooperative projects involving laboratory incubations, greenhouse studies and x-ray absorption spectroscopy to elucidate the role of organic and inorganic components of biosolids and other residuals in binding metals (Brown et al., 2003a; Hettiarachchi et al., 2003a, b, 2006; Ippolito et al., 2009, 2013; Obrycki et al., 2016; Ryan et al., 2003, 2004a; Scheckel et al., 2004). We have demonstrated that biosolids and other soil amendments can reduce the bioavailability of metals in contaminated systems (e.g., Attanayake et al., 2014; 2015; 2017; Barbarick et al., 2015, 2016, 2017; Basta et al., 2001; Brown et al 2003b, 2007; DeVolder et al., 2003; Hettiarachchi and Pierzynski, 2002; Ippolito et al., 2010, 2014; Meiman et al., 2012), while developing various extractants to assess bioavailability of mineral and bioavailable fractions of inorganic contaminants (e.g., Basta and Juhasz, 2014; Basta et al., 2003; Brown et al., 2004; Rodriguez et al., 2003; Ryan et al., 2004; Schroder et al., 2003; Whitacre et al., 2017).

Our group’s research has broadened to encompass a range of measurement endpoints as we realize and understand the potential for metals to affect a range of receptors. The goal of this research is to evaluate functions of restored ecosystems utilizing tools such as in vivo and in vitro assays, toxicity assays and measures of microbial community dynamics (Alexander et al., 2003; Basta and Juhasz, 2014; Basta et al., 2003; Brown et al., 2004; Schroder et al., 2003; Sullivan et al., 2005). As a result of cooperative research conducted by members of W3170, in situ remediation options, including biosolids and other residuals, have been utilized on a number of EPA Superfund NPL (National Priority List) sites, contaminated urban soils, mine lands, forest fire burned areas and overgrazed and degraded ecosystem sites. The tools developed for this research have broadened our understanding on the functioning of soils amended with biosolids or residuals.

The sustainability of biosolids application to agricultural lands has also been demonstrated by evaluating the effects of biosolids application on various aspects of soil functionality, recently termed “soil health.” While the implications of this research are being recognized in agroecosystems and remediation of contaminated sites, such research is also needed for rehabilitation of urban landscapes. Among the greatly expanding potential markets for exceptional quality (EQ) biosolids are uses for urban agriculture, turfgrass and other vegetated urban landscapes on anthropogenic soils.

Among the challenges in urban agriculture and other anthropogenic soil landscapes are their commonly degraded nature and potential presence of contaminants in such soils. In contrast to natural soils, human activities strongly influence urban soils through the removal of topsoil, physical disturbances, heavy vehicle traffic and addition of foreign materials (e.g., asphalt, bricks, glass, plastic, etc.), which ultimately result in a highly impaired soil (Craul, 1985; Gregory et al., 2006; Beniston and Lal, 2012). These disturbed soils are characterized by soil compaction, increased bulk density, reduced water infiltration rates and aeration, low water holding capacity, low organic matter content and low fertility, which ultimately limit crop growth and yields and create major constraints for productive urban agriculture (Gregory et al., 2006; Beniston and Lal, 2012).

EQ biosolids can provide organic matter and nutrients necessary to improve anthropogenic soils and promote vegetative establishment and growth. EQ biosolids are by-products of wastewater treatment generated by Processes to Further Reduce Pathogens (PFRPs) and possess low vector attraction and pollutant concentrations. Such products are suitable amendments for landscapes having high public access. Research needs for these newly developed products include quantifying N and P availability and C sequestration potential in anthropogenic soils. Initial work on these questions has been performed (Alvarez-Campos et al., 2018; Alvarez-Campos and Evanylo, 2019a; Brown et al., 2016c), but additional research is needed to ensure appropriate EQ biosolids management for urban landscapes. Biosolids blended with compost and/or other residuals have been shown useful in reducing exposure to Pb contaminated soil, improve soil health and protect public health (Obrycki et al., 2017). The multistate research group will continue research to improve our understanding of this in field studies, focusing on changes in soil attributes that may have implications for altering soil quality/health (e.g., soil physical, chemical, nutrient, and biological characteristics).

Another area of concern is the fate of residuals-borne trace organic chemicals (TOrCs) in soils. Classes of TOrCs include estrogenic compounds, personal care products, pharmaceuticals, and PFAS (Codling et al., 2018; Dalahmeh et al., 2018; Stahl et al., 2013; Sepulvado et al., 2011; Topp and Colucci, 2004; Xia and Pillar, 2004). A wide range of TOrCs in streams in the vicinity of wastewater treatment plants and concentrated animal feeding operations (CAFOs) has been frequently reported. The fate and persistence of these compounds during biosolids stabilization processes or following land application of residuals and non-potable water are not fully understood. Persistence in soils and potential for ecosystem effects as a result of residuals and non-potable water land application is a critical area requiring additional research.

In particular, some of the greatest challenges for expanding the beneficial use of treated wastewater effluent and residuals (such as biosolids) are concerns associated with PFAS. Based on this extensive use in a myriad of products, their existence in the environment is ubiquitous. Land application of biosolids has been shown to disseminate PFAS in soils and subsequently be assimilated by crops and leached to groundwater (Bizkarguenaga et al., 2016; Blaine et al., 2014a, b; Lee et al., 2014; Lindstrom et al., 2011; Sepulvado, et al., 2011; Navarro et al., 2017). Biological degradation processes that often time reduce TOrC loads in wastewater treatment and in land-applied biosolids do not alleviate PFAS load since any microbially degradation that occurs leads to persistent perfluoroalkyl acids (PFAAs) (Liu et al., 2013). Even small contributions of PFAAs to water sources can be problematic from a management standpoint given the low ppt levels being proposed or already implemented as screening levels or actual health advisory levels by some states (e.g., 14 ppt in NY).  On March 22, 2019, Maine’s Department of Environmental Protection (DEP) released a memorandum requiring sludge/biosolids program licensees and sludge/biosolids composting facilities to test their materials for PFAS. Any material exceeding the screening standards set for three PFAAs (2.5 mg/kg PFOA, 5.2 mg/kg PFOS or 1,900 mg/kg PFBS) may not be land-applied until DEP approves otherwise.

A final area of concern for the W3170 workgroup has been on irrigation water sources. This particularly holds true due to the fact that fresh water sources for irrigation are limited, and impending water shortages are motivating the intentional reuse of degraded waters (O’Connor et al., 2008; Blaine et al., 2014b). While the application of treated or partially treated wastewater effluents to cropped and forested lands has long been practiced, other sources of degraded water (stormwater, irrigation return flow, gray water, and CAFO effluents) are available to meet anticipated shortfalls. In conjunction with degraded water use, soil application of residual products may, in fact, have positive effects on drought-stressed crops. Several researchers have noted improvements in crop drought tolerance and crop yield with the biosolids land application (e.g., Cogger et al., 2013; Heckman et al., 1987; Zhang et al., 2005), with speculation geared towards improvements in soil water relations (Brown et al., 2011). Since many of the major reuse opportunities involve water applications to soil systems (e.g., irrigation), with or without residuals application, addressing the benefits, risks, and sustainability of degraded water reuse logically fits within the scope of the proposed research project.

In summary, there is a continued need for research on contaminant lability and bioavailability in both residual-amended soils and in contaminated soils restored with residuals. New ecological endpoints must be investigated to improve risk assessment to ensure human health and environmental safety. Research is also needed to maximize yields via the use of residuals and reclaimed wastewater. Both offer potential alternatives to current, sometimes environmentally detrimental, agricultural and land restoration practices. The experience and expertise of W3170 in addressing these issues are widely recognized and W3170 is well positioned for continued success. The W3170 membership offers the advantage of including institutions and entities (universities, USDA-ARS, US EPA, municipal government utilities) from across the entire US. Such collaboration enables discoveries to account for widespread differences in climate, soils and residual types and sources, whose fate, transport and impact will vary due to across these factors.