I need to be careful around technology.
SCWO (Supercritical Water Oxidation) was too much for me in my commentary in last week’s Biosolids in the News. Those championing SCWO in California say I got it wrong in last week’s blog. I apologize to them, and remain glad that they, not I, are taking on a technology that is so difficult for me to comprehend.
I return to the agronomic roots from which I came. Alas, even there, so much is new, and the science is increasingly difficult for me to comprehend.
The challenge raised by Dr. Jordan Peccia in “We should expect more from our sewage sludge,” particularly his position that land application is not sustainable, reminded me that his paper “Toward a consensus view on the infectious risks associated with land application of sewage sludge” had made an important point that our community has yet to squarely address. He determined that anaerobically digested cake had levels of human pathogens not well represented by indicator fecal coliform. Particularly, he attributed higher health risks to noroviruses and adenoviruses, through human exposures via aerosol dispersion during land application of cake. The science tools available twenty-five years ago as a basis for Part 503’s fecal coliform-based standard have been long since eclipsed by new genomic testing tools. Dr. Peccia is using new tools which we have not yet incorporated into our biosolids testing. But we need these tools, if for no other reason that they might help our case for biosolids safety. I have the notion that exposure to the microbes we would discover in biosolids might actually have benefits. Scientists working on the Hygiene Hypothesis identify positive effects of bacterial exposures. The apostle of this hypothesis, Graham A.W. Rook, is still actively promoting the notion that excessive cleanliness result in “lost friends” in our gut, to which he links many of the pernicious diseases of western culture (Hygiene Hypothesis and Autoimmune Diseases ).
What is more, the spate of research into the “human gut microbiome” suggests that Americans have an unhealthy impoverishment of their human gut flora. Our condition arises, apparently, from our inadequate exposures to microbes in food, soil, and water environments, particularly as children. The 2012 Nature article, Human gut microbiome viewed across age and geography, examined “composition and functional repertoire of the fecal microbiota” and concluded that the U.S. gut lacked health diversity. The authors had no positive words for our gut flora in comparison to the guts in Amazons of Venezuela and rural Malawi. I rather doubt these populations have biosolids treatment to a Class A standard. If what is missing in our world is a healthy dose of exposures to a rich diversity of microbes, maybe biosolids can help. This may be farfetched in practice, but we can at least deploy tools of genomic research to ask all pertinent questions about human exposure to biosolids, taking in the full gamut from health benefits to health risks. I worked in and around biosolids for 21 years without taking a single day of sick leave, so from a solely personal, anecdotal viewpoint, I am wholly behind my new “Biosolids Hygiene Hypothesis.” Let me imagine now how my unsolicited proposal to WERF will read….
The biosolids research community, in its search for deeper understanding of fundamental microbial processes at work in the human world, is not alone.
The search in the microbial world is fierce for the next generation of antibiotics. The world is in sore need of new treatments that overcome the antibiotic resistance evolving among so many feared human diseases. The solution will be microbial, and soil will be the source, as it was a hundred years ago. July’s CSA News reports a breakthrough in new methods of finding antibiotic soil microbes. The article “The hunt for antibiotics in soil” [not yet available on-line] describes microbiologist Slava Epstein’s effort to develop the “iChip,” a candy-bar-sized cartridge that is inoculated and buried in soil for culturing candidate bacteria. This is among the first really new tools in a hundred years for identifying “uncultured” soil bacteria of potential medical benefits. Described in this article Newly discovered antibiotic kills pathogens without resistance, “…only 1 percent of [soil microorganisms] will grow in the lab, and this limited resource was overmined in the 1960s.” With the new “iChip,” Epstein has “since assembled about 50,000 strains of uncultured bacteria and discovered 25 new antibiotics, of which teixobactin is the latest and most interesting…”
The search is fierce, too, for microbial support for sustainable crop production. July’s CSA News, once again, had several articles on this topic. It was the Members Forum which raised the hot button issue of whether organic nutrients have a place alongside chemical fertilizers in meeting goals of global sustainable agriculture. The conventional wisdom is that crop roots take up only mineralized nitrogen (ammonia and nitrate), so why not just rely on chemicals? But Joseph R. Heckman, Rutgers University, and Alison M. Grantham, Pennsylvania State University, assert that current research shows crop production is enhanced and made more efficient when plants utilize organic nitrogen, both through symbiotic mycorrhizal fungi and through direct absorption of amino acids released by decomposing organic matter.
This is no small issue for our biosolids community because organic nitrogen is what we have! “Plant available nitrogen” is more than a regulatory calculation foisted on us by guidance documents. PAN is the consequence, in large part, of microbial and root activity upon a rich array of organic molecules. I suspect microbes abound for all sources of organic nutrients, be they manure-borne, crop-residue borne or biosolids-borne. What if “soil invigoration” and “soil health,” touted by organic farming advocates, is a real phenomenon that only now, with advanced scientific tools, we can give proof to with the use of biosolids?
The importance of organic nutrients is the research agenda for a new “big name” in soil fertility, Chanyarat T. Paungfoo-Lonhienne (you can agree it is a big name). This young female Australian researcher has written in her paper Past, present and future of organic nutrients: “With the need to improve nutrient efficiency of crop production and recycling of nutrients contained in wastes from agriculture and other industries, organic nutrients hold promise for use in modern crop systems and warrant new approaches to plant nutrition.”
While her research is in support of the multi-billion dollar organic food production system, the science is transferrable to biosolids. Science has shown that organic nutrients include a variety of substances that are “biostimulants,” aiding in nutrient absorption, disease suppression and crop growth. A recent review article by Pamela Calvo and others, Agricultural uses of plant biostimulants, stated: "The cited literature also reveals some commonalities in plant responses to different biostimulants, such as increased root growth, enhanced nutrient uptake, and stress tolerance. "
This new science in organic nutrients and biostimulants fits hand-in-glove with research sponsored by DC Water at Virginia Tech with Dr. Xunzhong Zhang. Dr Zhang’s breakthrough research with biosolids as biostimulants includes such hot titles as: Impact of Biosolids on Hormone Metabolism in Drought-Stressed Tall Fescue and Corn and Soybean Hormone and Antioxidant Metabolism Responses to Biosolids under Two Cropping Systems. In this second one, he concludes, “The research demonstrated that biosolids application improves leaf antisenescence hormones, osmoprotectant, and antioxidant metabolism to increase grain yields, especially under drought stress.” Dr. Zhang presented on this work at the MABA symposium two years back “Biostimulants released from biosolids have impact on crop stress tolerance and yield."
I believe research will confirm that biosolids is an organic nutrient and biostimulant that boosts crop growth. I believe the science will show that biosolids ought to stand alongside the suite of organic nutrients already prized by certified organic farmers. But, we need to pony up the funding for this type of research. Then, with the science in hand, we will have proved that not only do we “expect more of our sewage sludge,” we deliver.
I can imagine the day when we will want to proudly label “these crops grown on High Quality Biosolids,” because we will be doing better than organic farming.
We will be doing Biosolids Farming.