Criticism and Compliments from Biosolids Research

Memorial Day can bring tears to my eyes. A news story in this Monday’s Philadelphia Inquirer, Honor the Fallen by Being People of Character, ends with, “Help us to honor our loved ones by bringing their model of character to your own lives. Act with courage, integrity, leadership, and service…. Aim for more than OK.”

More than anything, I want our work with recovery of resources from biosolids to “Aim for more than OK.”  “Cheap and easy” is not the test of good biosolids management, and my belief is that our profession has been for a while now on the high road. But we all, as humans, tend to ignore evidence that is contrary to our beliefs -- just go back to this great article from two years ago,  “We are all confident idiots.”

Integrity includes listening to our critics.  We have a few familiar biosolids opponents, commenting on local news controversies, and who are out there deploying the “sludge activists toolkits” (see “”). We occasionally have the newly-awakened gadfly, for example resurrecting long-ago discredited, ex-EPAer David Lewis (see Mother Earth News article). But what about those with apparently greater credibility, those who have published in peer-reviewed science journals?

Ellen Z. Harrison, who retired years ago from Cornell’s Waste Management Institute, led the work on a few journal articles which, from the perspective of time, helped focus our own profession’s research priorities in response. She was primary author on Land application of sewage sludges: an appraisal of the US regulationsOrganic chemicals in sewage sludges,  and Investigation of Alleged Health Incidents Associated with Land Application of Sewage Sludges.  Her argument was primarily that biosolids land application should be suspended until scientists had gone far further in understanding exposure pathways, interactions and risks arising from a larger array of elements and compounds present in biosolids.  We, of course, disagreed.

Along with Harrison, other skeptical scientists jumped onto questioning the safety of constituents in biosolids.  Robert Hale, Virginia Institute of Marine Science, in 2001 discovered flame retardant chemicals in biosolids, “Flame retardants: Persistent pollutants in land-applied sludges.”  He declared biosolids to be a significant source of environmental contamination, despite significant evidence to the contrary (see the good work from Chicago  “Triclocarban, triclosan, polybrominated diphenyl ethers, and 4-nonylphenol in biosolids and in soil receiving 33-year biosolids application”).

Another skeptic is Rolf Halden, a “sustainability scientist” at Arizona State University.  Dr. Halden presides, somewhat ironically, over the National Sewage Sludge Repository. which is the entire vault of representative biosolids samples from US EPA’s two national surveys. Biosolids has made his laboratory very productive:  National inventory of perfluoroalkyl substances in archived U.S. biosolids from the 2001 EPA National Sewage Sludge Survey;  National inventory of alkylphenol ethoxylate compounds in U.S. sewage sludges and chemical fate in outdoor soil mesocosmsDetection and Occurrence of N-Nitrosamines in Archived Biosolids from the Targeted National Sewage Sludge Survey of the U.S. Environmental Protection Agency; and, Brominated flame retardants in U.S. biosolids from the EPA national sewage sludge survey and chemical persistence in outdoor soil mesocosms.  This archive was also used for the attention grabbing publication Characterization, Recovery Opportunities, and Valuation of Metals in Municipal Sludges from U.S. Wastewater Treatment Plants Nationwide that asserted “the 13 most lucrative elements (Ag, Cu, Au, P, Fe, Pd, Mn, Zn, Ir, Al, Cd, Ti, Ga, and Cr) [had] a combined value of US $280/ton of sludge.”

But Dr. Halden’s big idea is to use fresh sampling of biosolids from across the United States in a type of early-warning system for today’s human exposures to a wide range of organic compounds that may accumulate in human bodies:Wastewater Treatment Plants as Chemical Observatories to Forecast Ecological and Human Health Risks of Manmade Chemicals.

So far this idea has not caught on among biosolids professionals, but not because additional study is not needed. WERF has undertaken a comprehensive survey of the scientific literature about what is known about chemicals that might end up in soil from biosolids applications (Trace Organic Chemicals in Biosolids-Amended Soils: State of the Science Review  ). WERF has turned to the industries who are potential sources of such chemicals to obtain their background information:Gathering Unpublished Data for Compounds Detected in Biosolids.  Other science teams have monitored biosolids for persistent pollutants and provided some important findings: Contaminant risks from biosolids land application: Contemporary organic contaminant levels in digested sewage sludge from five treatment plants in Greater Vancouver, British Columbia . This study found that “the concentrations of petroleum hydrocarbon derived substances in biosolids has not decreased within the last decade or more in the WWTPs studied, and—unlike persistent chlorinated compounds—the associated PAHs and other hydrocarbon constituents merit careful consideration, especially in the context of repeated land-application of biosolids.”

The allegations that land application has caused illness have been very hard to manage with science. We who have worked with biosolids up close and every day are completely confident of a clean bill of health. But we have responded to this common concern, and , the Water Environment Research Foundation carried out the project A Protocol for the Surveillance and Investigation of the Concerns Reported by Neighbors of Land Application (Biosolids and Other Soil Amendments). Importantly, scientists such as Drs. Ian Pepper and Charles Gerba at the University of Arizona produced a series of journals framing the exposure risks from land application of biosolids (as in Sustainability of Land Application of Class B Biosolids ).  WERF also sponsored several important studies in pathogen content in biosolids and in examining alternative microbial indicators of biosolids stability (see, for instance, Pathogen Risk Indicators for Wastewater and Biosolids).

But the tools of science evolve, and the scientific questions that can be addressed with those tools expand, too.  Jordan Peccia’s laboratory at Yale University has characterized a large suite of microbial constituents beyond the traditional ones in our field: Survey of Wastewater Indicators and Human Pathogen Genomes in Biosolids Produced by Class A and Class B Stabilization Treatments. His work, here and in other papers, is important for its identification of viruses that might be subject to environmental release.

Virginia government has contributed to our understanding of health risk risks of biosolids.  It directed the synthesis of a substantial body of research through a team of epidemiologists that produced a thoughtful and balanced report, “Health Effects of Biosolids Applied to Land: Available Scientific Evidence,”  dealing with concerns of biosolids-borne chemicals, pathogens, and radioactivity and their effect on human health was reviewed objectively. Biosolids was given a pretty good bill of health, but the report called for continuing a research agenda: “biosolids related health complaints should be investigated and documented so that trends or other indications of adverse health effects can be recognized and investigated in a timely manner by trained epidemiologists”.  This past Spring, the Virginia legislature called for an update of this report, a decade later, to explore where the science has taken us, and to update it by looking at other residuals and at the cost of achieving Class A standards for pathogen reduction. We can look for results perhaps in 2018.

We have Doctor Rufus Chaney, soon to retire from the USDA ARS, coming to the MABA Summer Technical Symposium in Baltimore, July 19th and 20th.  His presentation will argue “The Science of biosolids metals and xenobiotics show the importance of the matrix of biosolids, and the equilibration of metals and xenobiotics within biosolids before land application.”  Yet, even so, Dr. Chaney urges us onward with “… it remains important for the POTW community to support and conduct long term field research on beneficial use of biosolids both to address new questions, and to confirm the long term protections predicted from the few decades of field research available today.”

The work of Dr. Chaney has contributed enormously to our understanding of how the use of biosolids effects soil quality. His amazing oeuvre of science publications is joined by those of so many other well-published scientists.  Dr. Chaney is telling us his retirement in no way is an excuse to end science’s inquiry. Our integrity as environmental stewards obligates us to continue the scholarship.

Later this week I will be posting the Biosolids Research Update for June from Dr. Sally Brown. The topic is soil health.  This for me is the bottom line for resource recovery from biosolids.  We have a substantial body of work that shows that biosolids benefits are more than just OK.  The January 2016 issue of the Journal of Environmental Quality was devoted to papers from the Soil in the City conference in Chicago in July 2015. The work at Virginia Tech by Dr. Xunzhong Zhang on bio-stimulants has shown growth stimulation from biosolids and protection from drought (see Impact of Biosolids on Hormone Metabolism in Drought-Stressed Tall Fescue). Dr. Greg Evanylo is extending his three decades of work with biosolids effects with some specific new biosolids-based soil blends using DC Water’s new biosolids product BLOOM, with the great tagline, “Good Soil, Better Earth.”

These are all evidence that we are willing to go beyond just OK. I’m OK, You’re OK, But Biosolids is More Than OK.