A postcard from the Annual W3170 Research Meeting
The W3170 group of land grant university researchers focus on soils and soil amendments and biosolids. In October, they will become the 4170 group, as their 5-year project renewal by the U. S. Department of Agriculture (USDA) was recently approved. This research group’s history is long and important, playing a key role in the 1980s and ‘90s on collaborative multi-state science that was part of the basis for the federal Part 503 biosolids rule. Meeting annually, W170 then W1170 then W1270 and W1370, these scientists have addressed metals, pathogens, emerging contaminants, odors, best management practices, and the benefits to soils and cropping systems of biosolids and residuals additions – including carbon sequestration and climate change mitigation.
On June 25 & 26, 2019, W3170 met at USDA headquarters in Beltsville, MD. Once again, as every year, they exchanged current research updates, revealed preliminary and final data, and challenged each other in scientific debate. Some have been around since W170: Nick Basta (The Ohio State University) and Lee Daniels and Chip Elliott (Penn State). Some from other early versions of the group: Jim Ippolito (Colorado State), Sally Brown (Univ. of WA), Ian Pepper (Univ. of AZ), and this year’s host, Greg Evanlyo (Virginia Tech). Some have joined in over time, including Ganga Hettiarachchi (Kansas State), Elisa D’Angelo (Univ. of KY), Carl Rosen (Univ. of MN), Hui Lee (Michigan State), Brian Badgley (Virginia Tech), Linda Lee (Purdue), and Maria Silveira (Univ. of FL). And some were notably absent: George O’Connor (Univ. of Florida) has formally retired and moved away, but his rigorous challenging questioning was still noted and appreciated – and emulated as best as possible.
This year, the meeting included regular municipal and government researchers including Chicago’s Guanglong Tian and U. S. EPA’s Carolyn Acheson and regional biosolids group and committee representatives Greg Kester (CASA), Bill Toffey (MABA), Robert Crockett (VBC), Lynne Moss (WEAT), and Ned Beecher (NEBRA). (Ned: “What an honor to be in the presence of rigorous scientists, absorbing what I could and marveling at what was going over my head.”)
There was talk of PFAS, yes, with the latest details from Linda Lee, including these updates:
Data from total fluorine assays (PIGE) are suspect. Her lab analyzed dental floss alleged to contain PFAS and found none. It may contain F, but so does toothpaste, and F is not the same as PFAS.
Contamination of lab samples remains a problem. PFAS analyses remain difficult.
PFOA precursors degrade fairly quickly and provide increases to total PFOA concentrations up to 40% over experimental time frames (weeks, months), whereas PFOS precursors degrade more slowly and may add more like 2%.
They may have observed a decline already in PFAS levels in one widely-available bagged biosolids product between 2014 and 2018, which is likely due to reductions in general use of PFOA, PFOS, and other PFAS, as well as source reduction efforts.
They are trying to understand leaching potential from biosolids-amended soils. New research from Brusseau, 2019 raised the concept of sorption of some PFAS in soils being different (greater) at the air-water interface.
PFAS treatment options remain limited: “no silver bullet.” Her group has evaluated nano metal activated carbon (finding some success with nano-FeNi-activated carbon - work ongoing), heat-activated persulfate, vitamin B-12, and the strong oxidant catalyzed permanganate (which did not work for them, in contrast to an earlier paper by other researchers).
Other chemicals of emerging concern were discussed, with findings corroborating similar past research - that most degrade in soils in reasonable time frames, except a few, which deserve further risk evaluation. Research at Chicago confirms degradation of many trace chemicals in the composting process. But the question of potential ecological impacts of mixtures of trace contaminants comes up still, occasionally; the argument that seems to address this relates to bioassays, for example, the fact that microbial communities in soils appear to respond favorably to biosolids additions, and they are some of the most-highly-exposed ecological receptors, as Sally Brown noted.
Speaking of soil microbes: several presenters provided eye-opening research. Ian Pepper reported on the literature review and summary he is preparing in response to concerns in the November 2018 EPA Office of Inspector General (OIG) report. To address the question of antibiotic resistance, he noted that research indicates that, “due to sorption and degradation, antibiotic activity does not build up in soil despite natural production by soil microbes and anthropogenic inputs. Natural production of antibiotics in soil has occurred for billions of years.” Regarding pathogens, he presented a table or research papers that, as a whole, dismantle claims of significant impacts or risks from pathogens in land applied biosolids. He notes:
“No peer-reviewed evidence of adverse public health effects resulting from microbial hazards associated with land application of biosolids
“In contrast, 2-3 outbreaks annually associated with run-off from land applied animal manures.
“Based on this record, one can conclude that the presence of pathogens in Class B biosolids does not adversely affect public health.”
“Does biosolids quality alter the structure of the soil microbiome? And what can changes in the microbial community tell us about the biogeochemical process changes resulting from biosolids addition?” Those were the questions asked by a group at Virginia Tech. Complex evaluation of genetic material determined the impacts on the soil microbial communities seems to be mostly about addition of resources (e.g. nutrients), rather than some innoculation effect.
Jim Ippolito, Colorado State, gave a fascinating talk on the developing Soil Management Assessment Framework, a spreadsheet integrating soil health parameters. He is using the framework to assess the health of soils receiving 20 years of biosoilds versus a control soil site, as well as a land reclamation site Leadville, CO.
Maria Silveira, University of Florida, reviewed the proposed changes to Florida’s biosolids regulations. Of abbout 340,000 dry tons of biosolids produced in the Sunshine State, ~2/3 are land applied (about equal amounts of Class A products and Class B bulk). Today, excess phosphorus (P) is a major statewide concern, because of large algae blooms. Up to 70% of the P applied to Florida land comes from fertilizers, and runoff from lawns and homesites sitting right next to water bodies is often ignored by public and media coverage, while biosolids have been getting some blame in the past two years. Proposed regulatory updates will change the P Site Index and require nutrient management plans be signed by a certified nutrient management planner or P.E. The Site Index will rely on Water Extractable P (WEP) testing and allow for use of different factors for different kinds of fertilizers, manures, and biosolids (e.g. 50% for conventional biosolids and 90% for biological P removal P).
Other research included the following:
Persephone Ma and Carl Rosen (Univ. of MN) researched use of sewage sludge incinerator ash as a P fertilizer (and additional source of copper and zinc).
Mike Badzmierowski (Virginia Tech) found that “increasing Fe concentrations in biosolids results in reduced GHG emissions, inundating aerobic soils for a prolonged duration results in a sudden, large pulse of GHGs upon drying, and increased soil clay (Fe?) content appears to lower most GHG emissions (contrary to most literature indicating finer-textured soils emit more N2O than coarse-textured soils, our study indicated lower N2O emissions).”