Saturday, July 17, 2021

Phosphorus is Taxing: A proposal for radically diverting phosphorus from biosolids

Phosphorus has been in the news lately, perhaps because I watch for all things “P.” I learned from one news report that yet another hypothesis has been explored to explain the high concentration of phosphorus on the Earth’s crust, one that points to the solubilization of P during a period of intense electrical storm activity at Earth’s creation (Lightning Might Have Sparked Early Life on Earth). The Atlantic story from February, “Humanity is Flushing Away One of Life’s Essential Elements: we broke phosphorus,” reminds us that the explosive rise of humanity on Earth over the past 200 years arose not exclusively with discovery of how fossil carbon could be deployed for mechanical energy, but also from the discovery of fossil sources of phosphorus that could boost agricultural production and, hence, sustain the era of industrialization.  I have also keyed in on the role of phosphorus in fresh and brackish waters in promoting excess growth of cyanobacteria, the source of HABs, or harmful algae blooms, which can kill fish, birds, pets and, not incidentally, people (Time for bold action to protect Lake Erie from toxic algal blooms: George A. Elmaraghy). It is this last news commentary that holds the most importance to us biosolids professionals.  The article points to the growing consensus that excess total soil phosphorus from organic amendments is responsible for dangerous HABs. This issue with phosphorus, with no clear solution, is just plain taxing to read.

Compared to carbon in the political and social marketplace of environmental ideas, phosphorus management is woefully undervalued.  Yet, it shares some interesting parallels.  The unrestrained release of carbon dioxide from fossil fuel use is akin to the unrestrained release of phosphorus from our agricultural and wastewater management systems. Both releases pose major environmental consequences.

Scientists and economists have spent decades delving deeply into ways of reducing the unrestrained release of carbon.  They look to internalize the external costs of carbon emissions and to compel conversion to a non-fossil fuel global economy using incentives consistent with our global economic system. Broad agreement has formed around the idea that the most promising control measure is a carbon tax. Even with this agreement, carbon taxation can barely get out of the starting gate (see Carbon Tax, Its Purpose, and How It Works). Its simpler cousin, carbon emission trading, is a voluntary marketplace for carbon emission trading. In that system, a ton of carbon equivalent is valued at about $20 (Value of Carbon Market Update 2020), but this is hardly a value that would sustain major innovation in the energy sector, hence the need for a tax.  A recent economic study suggested a tax of $50 per ton of carbon dioxide equivalent (Harnessing the Power of Markets to Solve Climate Problems).  NOAA estimates that the global emission of carbon in 2019 was 10 gigatons, which corresponds to a HUGE potential tax needed for economic leverage to solve a HUGE environmental challenge.

Phosphorus is also a huge environmental challenge.  Phosphorus flows from its source in mines, to farms, to soil, to food, and then to its ultimate release to sinks in river sediment and oceans, where it is lost to any possibility of beneficial recovery, even though phosphorus reserves essential for agricultural production may ultimately prove finite.  The flow of P is almost entirely uni-directional, in the same manner as the carbon in fossil fuels goes from mines eventually to the atmosphere where it is irrecoverable.  What is the voluntary marketplace for phosphorus emissions? What does the research on a phosphorus tax say about pricing? There is no market and there is no economic research. Agronomists, farmers, and environmental regulators have been struggling to understand and to manage the flow of phosphorus onto and off of farmlands without the benefit of such marketplace or research.

Persons smart in the study of sustainability have called attention this gap in the phosphorus issue.  The authors of Reconsideration of the Planetary Boundary for Phosphorus write of  “the contrast between large amounts of P needed for food production and the high sensitivity of freshwaters to pollution by P runoff. At the same time, some regions of the world are P-deficient, and there are some indications that a global P shortage is possible in coming decades. More efficient recycling and retention of P within agricultural ecosystems could maintain or increase food production while reducing P pollution and improving water quality.” This observation would clearly include recycling the phosphorus that is captured in biosolids. Similarly, in the article Phosphorus use-efficiency of agriculture and food system in the US, the researchers observe “Improving yields of livestock and crop cultivation without additional phosphorus input and reducing household food waste are shown to be effective measures to improve life-cycle phosphorus use-efficiency.” They call for “a concerted effort by all entities along the life-cycle for efficient use of phosphorus.”  That effort would naturally include us biosolids practitioners.

If a program in the wastewater profession exists for a “life-cycle for efficient use of phosphorus” I am having problems finding it.  The “big-thinkers” in the study of P know this, too.  In Our Losing Phosphate Wager, the writer concludes: “most of that phosphate-containing organic sludge is treated and sterilized …  But it is not recycled for use in chemical fertilizers… Let’s invest in methods of recycling this massive amount of phosphate waste.”

Why is it the case that so much phosphorus in wasted?  Current regulatory requirements and economic equations would have such “concerted efforts” and investments seem nonsense. The paper Cost effectiveness of phosphorus removal processes in municipal wastewater treatment pegs the cost of phosphorus removal from wastewater at $42 to $61` per pound of phosphorus, in comparison to the commodity value of phosphorus at about 12 cents per pound. P removal is evaluated at treatment plants for value other than fertilizer value. The 2019 WEFTEC paper “A Review for Practitioners of 10 years Industry Experience with P Recovery Technologies” frames the primary drivers as operational and maintenance savings, such as reduced polymer usage, improved cake solids, dependable permit compliance, and reduced struvite deposits in tanks and pumps. The imperative for phosphorus extraction technology has a noble aspect as resource recovery, but not a monetary or regulatory imperative.  A Wikipedia article on “peak phosphorus” duly notes “research on phosphorus recovery methods from sewage sludge has been carried out in Sweden and Germany since around 2003, but the technologies currently under development are not yet cost effective, given the current price of phosphorus on the world market.”

Yet in the Mid Atlantic region, high phosphorus concentrations in biosolids may well pose a threat to the goal of biosolids recycling. Environmental consequences of phosphorus releases have grown in this region, particularly in the harm to the Chesapeake Bay and Great Lakes “sinks.”  The Great Lakes Restoration Initiative (GLRI) confers “a priority to reduce phosphorus runoff” for reducing HABs, harmful algae blooms (Preventing HABs)   Approaches for reducing phosphorus releases to the Chesapeake Bay are extraordinarily rife with economic, technical and political complexity, as implicit in the Chesapeake Bay Foundation’s Phosphorus Management description of Maryland’s Phosphorus Management Tool, and by the Pennsylvania DEP’s proposal to introduce within its biosolids general permit aspects of phosphorus control.

These regulatory initiatives stem from work by soil and nutrient scientists that connect the dots between total soil phosphorus and phosphorus loadings in streams. Recent journal articles discuss these complex connections. Many agricultural regions have soils with excess phosphorus. In the report A statewide assessment of the impacts of phosphorus-index implementation in Pennsylvania we learn that “The soils data indicated that statewide about 50% of samples had P levels in excess of those required for optimal crop production.” These soils pose a risk for watersheds: The report The Challenges of Managing Legacy Phosphorus Losses from Manure-Impacted Agricultural Soils explains that “soil test phosphorus (STP) concentrations that far exceed agronomic optimum… from long-term manure applications often serve as a source of P via a gradual release of dissolved P in runoff or leaching events. These losses of “legacy P” from manure-impacted soils are difficult to control and are linked to water-quality degradation in sensitive water bodies, like the Chesapeake Bay.” Scientists have studied the option of stopping additional P additions, as might occur from ceasing use of manure and biosolids. The report  Agronomic and environmental phosphorus decline in coastal plain soils after cessation of manure application found that “over the 15 years, the M3-P across manure treatments declined steadily at 7.7–15.3 mg kg-1 yr-1.  ….sufficient P will persist for decades as indicated by the abundance of agronomic and environmental P pools.”

If organic residual sources of carbon, nitrogen, and micronutrients from manures and biosolids are to be used in agricultural systems, the sources will by necessity also contain phosphorus. Are there ways to reduce the potential for phosphorus impacts? One major way to reduce potential P release from biosolids is to precipitate the biosolids-borne phosphorus as an iron or aluminum mineral, as can be verified by the Water Extractable Phosphorus test (see Assessment of plant availability and environmental risk of biosolids-phosphorus in a U.S. Midwest Corn-Belt Soil). But for other technologies able to control P release from organic residuals, their deployment is spotty and their demonstrated cost-effectiveness at the farm level have not yet shown. Nutrient management planners surveyed in Pennsylvania recommended “PA-PI [Pennsylvania Phosphorus Index] should more strongly discourage manure application to fields with insufficient ground cover, near subsurface drainage and surface inlets, and during winter. In addition, the PA planners said the PA-PI should more strongly encourage soil conservation practices such as no-till, use of cover crops, and vegetated buffers” (Nutrient management planners' feedback on New York and Pennsylvania phosphorus indices). Since much manure and biosolids are surface applied as part of a no-till conservation plan, one study (Best management practices to minimize agricultural phosphorus impacts on water quality) suggested: “ … the one-time plowing of P-stratified soils may reduce the long term loss of P in surface runoff as long as plowing induced erosion is minimized, providing landowners an additional option in keeping these soils in production under P-based nutrient management strategies.” Yet, but this approach is not regularly used, nor is it officially sanctioned. The report One size does not fit all: towards regional conservation practice guidance to reduce phosphorus loss risk in the lake erie watershed concludes “however, the application of specific conservation practices in certain environments (e.g. no‐till with surface application, cover crops) may not be effective and can even lead to unintended consequences.”

We biosolids managers have a conundrum in our approach to phosphorus. In the mid-Atlantic region, many of the farmlands to which biosolids might beneficially and economically be delivered have soils with phosphorus levels already adequate for crop growth.  We also have technologies available that can capture a significant proportion of the phosphorus, removals of 40 percent or better of total loads of phosphorus received in the effluent, and in a form that can be delivered to farms and soils in need of phosphorus.  But we do not have a driver in place that can match the cost of phosphorus extraction at our treatment facilities to the benefits of reducing phosphorus release to the environment or of returning phosphorus to agricultural regions that need it.  Purely hypothetically now, and for the sake of argument, what if a phosphorus tax were applied to the discharge of phosphorus to our publicly owned sewers, the proceeds of which would be directed to farmers or to wastewater operations or to both? Phosphorus is an issue which, like climate change, resists a compartmentalized, “one-size-fits-all” solution. We need innovative approaches and we need financial resources.  Indeed, the situation with biosolids phosphorus is taxing.

Remediating Urban Soils: How biosolids can reduce exposure to toxic lead

 The element lead (Pb) caught media attention in January 2021. With headlines on politics and covid screaming, missing the news coming out of Flint, Michigan, would not have been too surprising. But the event should have easily caught the attention of the those of us who have worked in the public water sector. The Zoom-based court line-up of elected and appointed officials, including an ex-governor, charged with causing exposure of lead to children in Flint, Michigan, was eye-popping.  The NBC News headline read: “Ex-governor, 8 other former Michigan officials charged in Flint water crisis: Charges stem from ‘the largest criminal investigation in the history of the state of Michigan,’ the attorney general says.”  Public infrastructure, improperly managed or intentionally mismanaged by government leaders, can harm lives and can earn no-joke jail time.

Childhood exposure to the element lead is arguably a public health and environmental issue of the greatest consequence facing public managers. Exposures occur in multiple media -- air, water, and soil media – thereby crossing regulatory domains.  Emissions arise from legacy sources that are invisible more than releases from current activities. Lead exposure is old news, not the current hot button, as it is an issue that has afflicted civilization literally for millennia.  Financial and media resources currently drawn to PFAS might be better focused on lead if the goal is meaningful benefits to public health.

How big a problem is childhood lead exposure? Despite long-standing programs, such as abatement of lead paint in old homes and ending use of leaded gasoline, children in impoverished communities are harmed even today by lead, and the impact on their lives will be felt decades into the future. An article like Association of Childhood Blood Lead Levels With Cognitive Function and Socioeconomic Status at Age 38 Years and With IQ Change and Socioeconomic Mobility Between Childhood and Adulthood casts lead toxicity in an urgent light for its long-term effects. Even relatively low levels of exposure are concerning. This point is made in Low-Level Environmental Lead Exposure and Children’s Intellectual Function: An International Pooled Analysis: “We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 μg/dL is associated with intellectual deficits…. childhood lead exposure was associated with lower cognitive function and socioeconomic status at age 38 years and with declines in IQ and with downward social mobility. Childhood lead exposure may have long-term ramifications.” 

Despite the attention to Flint, drinking water is not the major source of childhood exposure to lead. The article Children’s lead exposure: Relative contributions of various sources  points to dust and soil as the large risk: “the Flint water crisis, first recognized in 2015, continue to be regularly covered by the press … [but] lead contamination of soil has not received even a fraction of this consideration.” Urban soils are a large source of unregulated childhood exposure to lead. Lead concentrations in inner-city soils as a factor in the child lead problem bluntly concludes “Our findings pose environmental and public health issues, especially to children living within the inner-city.”

Wherever scientists look at soils in old urban centers, they easily find lead at concentrations above the EPA Safe Soil Level of 400 mg/kg. This has been true In New York City (Trace Metal Contamination in New York City Garden Soils and  Lead in New York City's soils: Population growth, land use, and contamination), in Cleveland (Management Options for Contaminated Urban Soils to Reduce Public Exposure and Maintain Soil Health), in Baltimore (Biosolids compost amendment for reducing soil lead hazards: a pilot study of Orgro® amendment and grass seeding in urban yards) and in Philadelphia (Relationship Between Total and Bioaccessible Lead on Children’s Blood Lead Levels in Urban Residential Philadelphia Soils).

The concern for lead risks is raised when urban soils are used for community gardening.  Many cities have programs to support gardening while explicitly addressing soil toxicity risks. The US EPA has been on the front lines of providing advice to city gardeners. EPA’s publications BROWNFIELDS AND URBAN AGRICULTURE: Interim Guidelines for Safe Gardening Practices and REUSING POTENTIALLY CONTAMINATED LANDSCAPES: Growing Gardens in Urban Soils are core documents.  Many cities have their own guidance document, for example “Soil Safety and Urban Gardening in Philadelphia.” Soil scientists have offered advice on safe gardening approaches: Lead in Urban Soils: A Real or Perceived Concern for Urban Agriculture? Another scientist proposes avoiding vegetables known to accumulate lead and other metals (Increased risk for lead exposure in children through consumption of produce grown in urban soils).

But community gardening is only one of several risks to children posed by lead-bearing soils. The journal article Mechanisms of children’s soil exposure concluded: “Soil is a source of contaminant exposure that must be evaluated when assessing environmental conditions and children’s health.” The survey of NYC soils shows that backyard soils have high metal levels: “Many of the soils analyzed exceeded the limits for Pb, Cr, As, and Cd levels. Higher percentages of home gardens are contaminated than community gardens.” The exposure pathway to children is more direct in backyard soils than in community gardens. The report Resuspension of urban soils as a persistent source of lead poisoning in children: A review and new directions  explains “… recent work on particulate resuspension and the role of resuspension of Pb-enriched urban soils as a continued source of bio-available Pb both outside and inside homes…. A strong seasonal relationship is found between atmospheric particulate loading and blood Pb levels in children….”

Risks from exposure to dust from backyard soil is usually outside the regulatory purview of environmental and health officials at local, state, or federal governments.  In Philadelphia, unexpectedly high blood lead levels in children resulted in a track down by investigative reporters to legacy soil contamination in gentrifying neighborhoods, where industrial lands were converted to home sites. The 2017 award-winning expose’ “In booming Philadelphia neighborhoods, lead-poisoned soil is resurfacing” included testing residential soils for lead, with some results as high as 10 times the EPA recommended soil level, and with neighborhood children having blood lead levels substantially above the 5 micrograms per deciliter action level.

Scientists have studied ways of reducing risks of high blood level levels of lead in children arising from contaminated neighborhood and backyard soils.  The 2004 review article Reducing Children’s Risk from Lead in Soil discusses chemical reactions in soil and in the human body that can reduce lead adsorption, also termed lead bioavailability or bioaccessibility.  The report Linking elevated blood lead level in urban school-aged children with bioaccessible lead in neighborhood soil explained that “bioaccessible Pb was a much stronger predictor of BLL [blood lead levels]."  Amendments rich in iron and aluminum appear to reduce lead bioavailability (Effect of soil properties on lead bioavailability and toxicity to earthworms). Another study (Variability of Bioaccessible Lead in Urban Garden Soils) pointed to phosphate and organic matter as significant for reducing lead bioavailability.  The 2004 article also targeted use of the nutrient phosphorus for reducing lead absorption in children, as phosphorus reacts with lead to form insoluble minerals that pass through the body.  The report Phosphorus Amendment Efficacy for In Situ Remediation of Soil Lead Depends on the Bioaccessible Method  looked at “Six phosphate amendments, including bone meal, fish bone, poultry litter, monoammonium phosphate, diammonium phosphate, and triple superphosphate….” One interesting recent paper suggests that a wastewater-derived phosphorus mineral, struvite, could reduce lead levels: Phosphate recycled as struvite immobilizes bioaccessible soil lead while minimizing environmental risk (“granular struvite can optimize trade-offs among soil Pb immobilization, crop Pb health risk, and P loss risk”). But the response of lead to phosphorus is not sure-fire. The journal article Soil solution interactions may limit Pb remediation using P amendments in an urban soil reports that “competing cations, such as Ca, Fe, and Zn, may limit low rate P applications for treating Pb soils.”

Success at reducing risks from lead-contaminated soils seems to improve with use of organic matter rich soil amendments. The study Management Options for Contaminated Urban Soils to Reduce Public Exposure and Maintain Soil Health tied reduced toxicity risks from organic-rich amendments to multiple factors. These characteristics include the vigor of the vegetative cover, the dilution of the toxic metals, the reduction of exposure of toxics at the soil surface, and the stability of soil aggregates for good drainage. The researchers also demonstrated that the soil amendments reduced exposures to toxic organic compounds: “mixing compost with the soil reduced benzo(a)pyrene content.”

Biosolids-based soil amendments have proved particularly effective because these products combine all three effective characteristics for reducing lead bioavailability – amorphous iron and aluminum, phosphorus in various mineral forms, and nutrient-rich organic matter.  The effectiveness of biosolids products had been first noted on research on brownfield and Superfund sites contaminated with lead and other toxic metals by mining and smelting activities. The paper  In situ remediation/reclamation/restoration of metals contaminated soils using tailor-made biosolids mixtures concluded “Tailor-Made Biosolids remediation of metal toxic soils allows effective and persistent  remediation at low cost….”  A review article of urban soil research (Case studies and evidence-based approaches to addressing urban soil lead contamination)  explained “composts, both biosolids and food and yard waste-based, have also been shown to reduce total soil Pb and Pb accessibility…. a trial program in Baltimore where the high Fe biosolids composts were added to Pb contaminated soils in 9 home gardens, reduced the bioaccessibility of lead in soil.  …Reduction in bioaccessible Pb is related to the absorption of Pb on high surface area Fe oxides.”  These results were confirmed in another study: Biosolids compost amendment for reducing soil lead hazards: a pilot study of Orgro® amendment and grass seeding in urban yards (“This study confirms the viability of in situ remediation of soils in urban areas where children are at risk of high Pb exposure from lead in paint, dust and soil”).

From all of this we have two big messages: health risks to children from lead-contaminated urban soils are significant, and the capacity of biosolids-based soil amendments to reduce health risks are persuasive. Yet, deployment of biosolids products to mitigate risks of exposure to urban soils is uncommon. A host of explanations can be offered: biosolids is a “tough sell” in urban communities; no regulations compel mitigation of lead in backyard soils; lead-based paint exposure in homes remain an urgent risk; and expensive local testing and demonstrations might be needed to support new programs. But does not the experience of the Flint water crisis teach us a lesson? The nexus of public policy in health and environmental management can collide with a vengeance when public leadership fails to act to protect the health of children. We biosolids managers have the knowledge and capacity to assume responsibility for advocating the fact that, when it comes to mitigating childhood lead risk, Biosolids is the Lead Story.    

Biosolids Dust: An important attribute in biosolids marketability

 Dust is a big deal! Viruses have so commanded the front stage of our news media that you may have missed other big “dust” stories. China is having a BIG dust problem. The article “Apocalyptic skies as Beijing hit by worst sandstorm in a decade” (March 15, 2021) explains winds off Mongolia are carrying a dense cloud of dust to Beijing. This is an issue with serious health and environmental implications (Characterization of the composition of dust fallout and identification of dust sources in arid and semiarid North China. The newspapers are happy to remind us that early Spring brings tree pollen, a phenomenon steeped in science  Pollen calendars and maps of allergenic pollen in North America.  Two weeks of dry weather in the mid-Atlantic, and wildfires are releasing unhealthy soot: “Wildland firefighter smoke exposure and risk of lung cancer and cardiovascular disease mortality.” While the dangers of dust-borne lead in homes is well established (Children’s Lead Exposure: A Multimedia Modeling Analysis to Guide Public Health Decision-Making), household dust contains many more compounds of concern, many of which we see also in our wastewater and biosolids, such as flame retardants and phthalates: Tracing the chemistry of household dust The sloughing skin that joins cloth fibers in the household dust. Worse yet, some of the dust may be radioactive (Health Implications of Fallout from Nuclear Weapons Testing through 1961). On a lighter note, we also learned in a January 2021 news article that amidst the load of anthropogenic dust, which has greatly accumulated in my house during the pandemic lockdown, is some very ancient dust (7 billion-year-old stardust is oldest material found on Earth), older than our solar system. Yes, dust is a big deal for scientists, inhabitants, and life in the world.

Dust is also important for us biosolids practitioners, too, but you would not know that from the paucity of professional news coverage and research on the topic.  The Water Environment Federation has brought into its website all papers and articles from several decades of conferences and publications.  These are found in Access Water. In this large database, 4,660 articles on biosolids are catalogued. While some 700 articles mention biosolids dust when dealing with treatment plant processes, to protect from fire, explosion and worker injury, only two papers treat dust as a key characteristic of biosolids products deserving consideration in the choice of treatment processes.  The first paper, from the 2017 WEF Residuals and Biosolids Conference, is  Not All Dryer Products are Created Equal, and the second is from WEFTEC 2019,  Worthless Dust or Valuable Resource? Drying Thermally Hydrolyzed Solids the Right Way.

The first paper, by Material Matter’s Lisa Challenger, makes the case for a eyes-wide-open approach to selecting technology for the desired end-use of the product. Challenger underscores the point that technologies identical in terms of Part 503 regulatory compliance (Pathogen Reduction PFRP Class A – Alternative 5 and Vector Attraction Reduction – Option 8) yield end products that are opposites in their suitability for distribution and marketing. The marketable heat-dried biosolids was a digested biosolids processed in a rotary kiln direct dryer and the non-marketable dried biosolids was an undigested biosolids dried in an indirect paddle-type dryer. In the second case, high dust, low density, and intense odors doomed the product’s use as a fertilizer, despite regulatory compliance with national standards.

The second paper, by HDR’s Stephanie Spalding and Sebastian Smoot, examines three attributes of biosolids product quality -- energy content, friability, and bulk density -- against various combinations of equipment and process trains and of user requirements. Too few case studies permitted the authors conclusive answers, but several themes were suggested by nine cases, and dustiness of the product was a key concern. High dustiness followed several process features: thermal hydrolysis of the entire solids flow, the use of iron as a coagulant, a drying process that agitated the solids, and post-treatment handling by truck and land application equipment. One or more of these features could yield dust that discouraged customer acceptance. 

Dust in biosolids products may be a problem for a variety of reasons, but human health effects are primary. If there were a “canary in the coal mine” for risks from biosolids dust exposure it would be treatment plant operators. I had not held much concern, ever since the Philadelphia Water Department was one of 4 compost facilities in a NIOSH health study. This lead to  “Respiratory Exposure Hazards in Composting” which determined: “Very high levels of dust, endotoxins, (1-3)-β -D-glucan and ammonia were measured in compost facilities depending on the location, activity and enclosure. Exposure appeared to be correlated with few respiratory health parameters, although no significant objective pulmonary function differences were detected between the study groups.” I drew from this the premature conclusion that community exposure to biosolids compost dust would be benign.

Since that workplace study of the late 1990s, new tools have become available for measuring and characterizing “dust.” Researchers have sharpened their understanding of the characteristics of airborne biological particles, especially with genomic tools for identifying microbes.  Dust of the kind from biosolids is more specifically defined as a bioaerosol:  “microbial fragments, constituents of cells and airborne biological particles that can consist of fungi, bacteria, pollen, fragments, constituents, particulate matter (PM10), and by-products of cells, that may be viable or nonviable.” 

Current research shows that organic waste treatment can be a significant source of bioaerosol exposures. The article Methods for Bioaerosol Characterization: Limits and Perspectives for Human Health Risk Assessment in Organic Waste Treatment describes “composting biomarkers” for identifying a “causality process between chronic bioaerosol exposure and disease onset, and finally, on defining common exposure limits.” Advances in microbiology expands the range of microbes exposures associated with wastewater treatment (Evaluation of Bioaerosol Bacterial Components of a Wastewater Treatment Plant Through an Integrate Approach and In Vivo Assessment): “next generation sequencing analysis was used also to identify the uncultivable species that were not detected by the culture dependent-method.” As new measurement tools are added, the range of potential risks seems to enlarge. In The size distribution of airborne bacteria and human pathogenic bacteria in a commercial composting plant “Seven out of eight HPB [human pathogenic bacteria] with a small geometric mean aerodynamic diameter had a high concentration in composting areas.”

Yet, while tools for measurement have improved, the attribution of risk levels has lagged. In Bioaerosol exposure from composting facilities and health outcomes in workers and in the community: A systematic review update the authors conclude “there is insufficient evidence to provide a quantitative comment on the risk to nearby residents from exposure to compost bioaerosols.” This kind of open issue is itself an issue, particularly from the viewpoint of environmental justice. The article Characterising populations living close to intensive farming and composting facilities in England observes that with regard to high exposures to bioaerosols from intensive farming “few people (0.01 %) live very close to these sites and tend to be older people. Close to composting facilities, populations are more likely to be urban and more deprived.” The key here is that science is in the early stages of exploring the human health risks of bioaerosols.

Low dust is a prized attribute of heat-dried biosolids pellets. In the WEF Conference paper Toronto’s Pelletizer Facility – A New Start, the “new start” included the aspiration that “dust production, resulting from friction during transport and handling, will be very low with the biosolids pellet product.”  To this attribute was also that of hardness: “pellet hardness is… slightly higher than that of chemical fertilizers… [such that] handling and spreading of the product is relatively easy and dust-free.”

While durability and dustiness are key attributes, no article in WEF Access Water discuss measurements of these attributes. Chemical fertilizer and wood pellet industries are keen to prevent pellets from turning to dust, a property they term durability. Hence, these industries deploy a “product durability index” and measure this with “product durability testers.” The PDI is “a standardized parameter for specifying the ability of the fuel pellets to resist degradation caused by shipping and handling.” For, under $4,000 you, too, can own a “Two Compartment Pellet Durability Tester.”  This tester subjects pellets to a tumbler that simulates conveyance and transport handling, and test results are reported as a percentage of pellet mass that degrades into dusty particles. This sounds as though this device ought to have a place in measuring durability and dryness of biosolids pellets, but it does not.

Though durability and dustiness seem to be secondary objectives in choice of treatment technologies, various pre-drying and post-drying options at the plant can modify these product attributes. Fine screening and digestion are treatment steps that reduce fibers and low-density organic matter, and subsequent dried product is denser than undigested biosolids. Post-drying screening is another step, and Challenger reports: “screenings are recycled back to the head of the dryer and blended with the cake product to avoid the “sticky” phase of the biosolids product typically returning and blending fine particles into the cake feeding the dryers, results in a denser product. “ 

What is more, the world stands ready to help with durability and dustiness. Many manufacturers provide granulators that could help us create a durable pellet, such as a Compost Pellet Machines and a Powder Granulator Machines; you can even buy on Amazon a Feed Pellet Machine. Though granulated products may still be dusty and odorous, you can add to it a coating.  Surface Chemists of Florida can customize a coating for dried biosolids; its SurPhase FLOW promises to “preserve your product’s integrity.” Similarly, ArrMaz can design a special DUSTROL® or GALORYL® dust control coating for biosolids.  Yet, these machines and coatings are an on-going expense to fix a situation that might have been otherwise avoided with better technology selection upfront.

The matter of control of biosolids dust is no light matter. Biosolids products that lack durability, that fail to withstand transport and land spreading and that consequently pose a risk of bioaerosol release are unlikely to be part of an economical, sustainable program. Each component of treatment, from screening, to digestion, to dewatering, to subsequent stabilization, warrants evaluation for its contribution to the “product’s integrity.” Just as the SARS-CoV-2 virus has raised global fears about invisible particles in the air we breathe, our industry cannot afford to be a source of invisible particles that raise public fears.  We ought to recalibrate our focus on technologies that minimize dust and bioaerosol releases in response to new health concerns and scientific capabilities, because Biosolids Dust is a Big Deal.   

Biosolids Boost to Productivity: Is biosolids a "multivitamin for the soil"?

 

They [farmers on Eastern Shore of Maryland] put in an order for pellets because they hear it keeps deer away from the beans, but they make a second order because they see a difference. I am not sure what it is, but it might be micronutrients.”  I was asking Synagro’s Steve McMahon about the aspects of dried biosolids that “sell.” This was not the first time I had heard these “pitches:” pellets are a deer repellent; pellets are like a vitamin pill for the soil. Are either of these aspects of biosolids true?

As we are experiencing with COVID-19 and with presidential politics, the lies we tell ourselves and the truths we hold as “self-evident” are hard to dig into. Can science help us avoid unexamined biases we hold and the lies we tell ourselves? With respect to biosolids, can science tell us if biosolids pellets repel deer and if biosolids are a vitamin for the soil?

Fascinatingly, even though billions of people are concerned with nutrition and many hundred thousand scientists attend to human and environmental health issues, clear irrefutable answers to basic questions are in short supply. Can there be any surprise, then, that clear irrefutable answers on biosolids are also in short supply?

Issue of human health remain controversial, and how science works to clarify these issues is a metaphor for how we use science to demonstrate the benefits of biosolids.

Isn’t it true that vitamins for the human body are good? Science is mostly NO, not supporting multi-vitamins.  “There is no indication that supplementation is necessary for healthy, non-pregnant, non-lactating adults” according to a 2019 review article Minimal Purposes of Multivitamins. Science supports Vitamin D for people without sun exposure, iron for women of child-bearing age, and folic acid for pregnant women, but almost nothing else. “Essential minerals,” like zinc, seem unsupported as necessary supplements. So, can we be sure biosolids as vitamin are necessarily good?

Is it true that foods labeled organic are more nutritious than conventional foods? The science is mixed, YES and NO. One review article (A literature‐based comparison of nutrient and contaminant contents between organic and conventional vegetables and potatoes) says, sometimes yes, sometimes no, but “it becomes difficult to justify general claims indicating a surplus value of organic over conventional vegetables and potatoes.” So, can we be sure the “organic” label would connote better nutrition.

Is it true that a wholly plant-based diet confers greater health than a meat-eating diet? The science is not clear, and mostly NO. A major study (Nutrition and Health – The Association between Eating Behavior and Various Health Parameters: A Matched Sample Study) out of Austria suggests that vegetarians are less healthy overall than folks eating conventionally. So, can we be sure biosolids users deploy biosolids for the right reasons?

Is it true that bacon is no good!? The scientific evidence is YES (Aw, say it is not true!). The 2020 review article Red and Processed Meats and Health Risks: How Strong Is the Evidence?  says“…dietary guidelines should continue to emphasize dietary patterns low in red and processed meats and high in minimally processed plant foods such as fruits and vegetables, whole grains, nuts, and legumes.” So, can we be sure biosolids is always good for soil, particularly considering pH changes, high phosphorus and low potassium.

Is it true that vegetarianism is better for the planet? The answer is YES, BUT. As the commentary “Why the debate between vegans and meat-eaters is pointless” says “it is a complex question exactly what kind of food system would be ideal… Keep an open mind.” So, are biosolids nutrients, contributing to the circular economy, infallibly preferred to fossilized sources?

Isn’t it true that avoiding GMOs makes a difference in a person’s health?  Again, the science is not clear.  As one large German study (Republished study: long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize) concluded: “Our findings imply that long-term (2 year) feeding trials need to be conducted to thoroughly evaluate the safety of GM foods and pesticides in their full commercial formulations.” So, are the organic micropollutants added to soil with biosolids clearly without risks?

Science cannot give us firm answers to such huge questions of human and environmental health. What can we expect of the answers about the safety and effectiveness of biosolids as a fertilizer, as a vitamin for soils that deters deer?

Are biosolids safe to use? The answer is a firm YES, at least as firm a conclusion as scientists are apt to make. My original “go-to” document is the iconic 2005 journal article Sustainable land application: An overview. No less significant is the 2002 WERF report Evaluating risks and benefits of soil amendments used in agriculture,” with its many hundreds of journal citations. But nothing quite rises to the most current resource than the collective response by soil scientists in the W4170 group, in its technical answers to the EPA OIG Report. The OIG “Report: EPA Unable to Assess the Impact of Hundreds of Unregulated Pollutants in Land-Applied Biosolids on Human Health and the Environment” was regarded as ill-informed and misleading by scientists familiar with the original regulatory development. Their response was brought together in the release of W4170 Multistate Research Committee Response to USEPA OIG Report No. 19-P-0002. The elements and compounds for which research into risks is warranted are countable on two hands.

Are agricultural soils in need of micronutrient supplementation? Science suggests the answer generally is NO. But this is a complicated question, and scientific answers require more resources of time and money than usually available.  One article that underscores this is Effects of Nutrient Antagonism and Synergism on Yield and Fertilizer Use Efficiency. This study starts out “great potential to increase the nutrient use efficiency, and consequently, yield levels by considering all essential plant nutrients (macronutrients N, P, K, Ca, Mg, and S and micronutrients Cl, Fe, B, Mn, Zn, Cu, Mo, and Ni) in fertilizer products and fertilization strategies.” The authors point out that “Studies about the effects of an annual fertilization with micronutrients to compensate for the removal by crop are rare.” Yet they hold the point of view that “balancing the composition, amount, timing, and mode of delivery of fertilizers to plants and soil, thereby aiming to overcome antagonism and stimulate synergism.” Does biosolids accomplish this balancing?

Can the balance of nutrients in soil affect the nutrient quality of the crops growing on them?  The answer seems to be YES. This area of scientific inquiry stands as its own discipline. A publication on this topic is Fertilizing Crops to Improve Human Health: a Scientific Review.  The conclusion of this report is “Fertilizer contributes to both the quantity and quality of the food produced. Used in the right way-applying the right source at the right rate, time and place-and on the right crops, it contributes immensely to the health and well-being of humanity.”

Do the micronutrients in biosolids impart a natural balance of micronutrients to the soil? The answer is “LIKELY YES.” The abundance and order of nutrient concentrations in biosolids mirrors that of the concentrations in plant tissues. This can be seen by lining up in rank order the essential nutrients for plant growth (K>N>Ca>S>Cl>P>Mg>Mn>Fe>Zn>Cu>B >Ni [Source: Plant nutrient functions and deficiency and toxicity symptom]) against the abundance and order of micronutrients in biosolids (Ca>N>P>Fe>Mg>Mn>K>Zn>Cu>B>Mo>Ni [derived from Targeted National Sewage Sludge Surveys). The primary outlier is potassium (K). Because K is a very soluble cation, it passes out in wastewater effluent rather than attach well to biosolids organic matter.  Biosolids concentrations better mirror plant tissue concentrations than soil concentrations.  Soil micronutrients loadings do not reflect micronutrient availability to crop roots  Vegetable crop scientist George Antonious demonstrates this fact in Elevated concentrations of trace elements in soil do not necessarily reflect metals available to plants.

Can the micronutrients in biosolids boost the yield and nutrient content of crops? The answer is LIKELY NO. I checked in with several of the scientists who worked on the W4170 report. First, most crops are not subject to deficiencies in micronutrients, so additions through biosolids will not register an effect.  Second, the vast majority of farmers we would be working with are among the top producers by design of our programs, with implemented nutrient management and conservation plans, with soils adjusted for proper soil pH, and with established soil metals test results. One of our science friends said a farmer once provided anecdotal testimonial to a zinc deficiency corrected by biosolids. Another researcher had worked on a coarse-textured, iron-deficient soil, and biosolids had demonstrated yield benefits. Another scientist cautioned about the opposite concern; deficiencies of Zn, Mn and Cu could be induced by lime-stabilized biosolids. But, in general, crop yield increases from the micronutrients contained in biosolids are not a “thing.”

Can biosolids be the basis for repairing soils with a demonstrably damaged balance of nutrients? The answer is YES. Iconic work by Rufus Chaney and Sally Brown showed how biosolids products repaired mine sites and damaged urban soils ( In situ soil treatments to reduce the phyto- and bioavailability of lead, zinc, and cadmium, Greening a Steel Mill Slag Brownfield with Biosolids and Sediments: A Case Study, and Biosolids Products for Urban Agriculture). What is more, biosolids enable poor soils to sustain economically valuable production, as in biofuel crops (Sylvis to support green coal mine reclamation project in Alberta).

The question of real importance:  can biosolids repel deer? Most likely YES!  The evidence is not just anecdotal. First, Milorganite stands behind this benefit of its dried biosolids product. It posts several “science” articles in its support (e.g., Using Milorganite® to temporarily repel white-tailed deer from food plots). Various professional columnists (e.g., Gardens All) and technical bodies (e.g., University of Georgia Extension) recommend use of Milorganite as deer repellant.

That is good enough for me. Certain lifestyle choices and biases are best held as faith, clear and true, rather than subjected to scientific scrutiny, incomplete and messy. My breakfast will continue to embrace blueberries and granola, full of antioxidants and fiber, and I will continue to have faith in biosolids as a “multivitamin for soil.”

Odor Denial Syndrome: Can we have an "impossible biosolids" without odor?

I believe our biosolids profession suffers from an “Odor Denial Syndrome.”  Despite repeated evidence in my Google Alerts for “biosolids” that odor complaints precipitate most cases of adverse media coverage, you wouldn’t guess that this is a problem for us, based on the scant attention to odors during recent months of technical conferences.  April’s WEF biosolids conference in Fort Lauderdale offered 100 technical papers, yet only one dealt with odors, and those odors were in-plant emissions during drying. The IWA’s Leading Edge Conference on Water and Wastewater Technologies was held in Edinburgh in June 2019, and no technologies offered odor mitigation as an attribute. Our own organization, Mid Atlantic Biosolids Association, put out a call this past winter for presentations for its July 2019 conference, and no presentation proposal dealt with odors. (Still, please come, it will be great! Check out the brochure!)

The Merriam-Webster on-line definition of “syndrome” is “a set of concurrent things (such as emotions or actions) that usually form an identifiable pattern.” One non-medical example posted to the Internet is a “not-in-my-backyard syndrome.” So, I think I have a case here for calling out our “odor denial syndrome.” It is a concurrence of odor nuisance complaints by communities and an absence of effective mitigation measures by agencies and their contractors.

The power of syndromes was hammered home in what was, frankly, an unexpected article in the New York Times about the “Havana Syndrome”. This is a strange “brain” ailment suffered by employees of the U.S. Embassy in Cuba, first reported several years ago.  One suggested cause of the brain ailment was a microwave “acoustic attack” (Microwave weapon caused syndrome in diplomats in Cuba, US medical team believes), and another suggestion was poisonings (Were the Cuban ‘Sonic Attack’ Victims Actually Poisoned?).  But by the time of the recent NYTimes article Was It an Invisible Attack on U.S. Diplomats, or Something Stranger? a third hypothesis had gained primacy: “the diplomats’ symptoms are primarily psychogenic.” In other words, the diplomats’ ailments were what is popularly called “mass hysteria,” but more scientifically termed “mass psychogenic illness,” a premise well covered in the article “Mad Gassers, toxic buses and the Havana Syndrome: What society still gets wrong about the way stress can make us sick.”

I have been following the term “mass psychogenic illness” with Google Alerts for well over a decade, since I first made a case for biosolids odorants as a trigger for a special kind of syndrome. I put together a research paper in 2007 titled Biosolids Odorant Emissions as a Cause of Somatic Disease:  What is Our Profession’s Response? I argued that biosolids odorants are of a chemical nature likely to trigger in susceptible people a “psychogenic illness,” which manifests as symptoms that align with the “sludge syndrome” put forth in Ellen Z Harrison’s paper Investigation of alleged health incidents associated with land application of sewage sludges.  According to Harrison, the symptoms of the sludge syndrome “most common are respiratory and gastrointestinal symptoms, skin disorders and headaches. Other symptoms frequently reported by numerous people include nosebleeds, burning eyes, throat or nose, flu-like symptoms, and fatigue.” 

In my 2007 paper, I argued that “sludge syndrome” symptoms arising from odor nuisances are predictable.  The human nose is exquisitely sensitive to organic sulfide and nitrogen compounds, and adverse reactions may be genetically “hard-wired.” I argued that biosolids managers ought to plan for maximum odor containment and be prepared with an appropriate, proactive response to those people who display such reactions. I had push back from the some biosolids practitioners because I had amplified the suggestion of adverse health effects from odors.  Activists caught wind of the paper and were angered by my assertion that the “sludge syndrome” was all in their heads. I couldn’t win. What is more, the Havana Syndrome is, for me, evidence of how powerful psychological responses are as “health effects,” and of how important it is for our industry to better manage biosolids odorant emissions. If highly trained intelligence officials can be brought down by environmental triggers, so too can the neighbors to our land application sites.

What has been the history of our wastewater industry’s response to the very significant issues of odors? Well, until about the year 2000, we had had essentially no response. In that year we pulled together, both through MABA and joined by the Water Environment Research Foundation, a significant research focus. Now that we are in 2019, can we say we have solved our odor problems?  After all, many dozens of journal articles and conference presentations have been prepared, and WERF has its four-phase report, leading to the “Biosolids Odor Reduction Roadmap.” We learned that adding iron salts ahead of dewatering seemed to be one strategy, that using presses instead of centrifuges for dewatering seems to be an option, and that waiting a couple of days after dewatering for odorants to subside was also a useful idea.  But, for all our effort, no breakthrough on odor mitigation was discovered.  Yet, it seems that WERF declared the research done. My faithful attendance at technical conferences and recent Google Scholar searches did not reveal any recent U.S. based research project.

That is why I was so amazed at the odor research work coming out of Australia over the past several years. Specifically, this is research that has Ruth M. Fisher’s name on it, a research associate at the University of New South Wale’s Water Research Centre.  I have now in my library her eight journal articles on the topic of biosolids odorants published between 2017 and 2019 (mind you, Dr. Fisher is only one year out from completing her PhD). Let me list these publications:

·         Variations of odorous VOCs detected by different assessors via gas chromatography coupled with mass spectrometry and olfactory detection port (ODP) system 

·         Odorous volatile organic compound (VOC) emissions from ageing anaerobically stabilised biosolids

·         Distribution and sensorial relevance of volatile organic compounds emitted throughout wastewater biosolids processing

·         Influence of Biosolids Processing on the Production of Odorous Emissions at Wastewater Treatment Plants

·         Sewer catchment effects on wastewater and biosolids odour management

·         Framework for the use of odour wheels to manage odours throughout wastewater biosolids processing

·         Emissions of volatile sulfur compounds (VSCs) throughout wastewater biosolids processing

But it is Fisher’s 2019 review article on biosolids odors that, if I had my way, would be mandatory reading for all practitioners -- Review of the effects of wastewater biosolids stabilization processes on odor emissions.  She reviews over 200 papers, and, importantly, she makes sharp observations and points us to important work ahead.

Fisher makes clear that we do not yet have adequate odor analysis methods, protocols and tools. Let me provide quotations from her review:

·         “However, due to the large range of odorants which have been reported for all stabilization methods, the use any single analyte to represent odor is likely insufficient and will lead to the underestimation of odor impacts… the focus on only TVOSCs is potentially limiting.”

·         “From a methodological perspective, both sensorial and analytical methods are needed for odor characterization.”

·         “…the dominant burnt odor quality detected in emissions from dried biosolids has not currently been linked to a responsible compound, however, it is likely an important odorant.”

·         “...a Dried Sludge Odor Wheel, which reported odorants… shows a need for emission analysis using a combination of chemical and olfactory measurement methods.”

·         “…qualitative approaches to odor control… are limited due to our lack of understanding of emission composition. The identification of odorants and the sensorial implications can provide a clear link between process performance and nuisance impacts.”

Fisher believes we need to study far closer than we have to date the link between processes and odors.  Again, here are some pertinent quotations:

·         “…the upstream plant configuration or operational performance were rarely reported, which makes links between emissions and WWTP performance difficult to establish.”

·         “To date little success has been reported in predicting the odor quality of biosolids produced using other (than anaerobic digestion) stabilization processes based on process operation.”

·         “Despite the large amount of research into emissions from anaerobically stabilized biosolids, no single operational parameter was found to predict biosolids odor. However, general trends between odor emissions and dewatering, storage, digestion and chemical dosing have been identified.... none were able to reliably predict the resulting biosolids odor quality…”

Even when we have some clear relationships between process and odors, Fisher suggests that actions that would reduce odor risks are not chosen. Here are some quotations:

·         “The choice of stabilization methods for biosolids processing should be influenced as much by the operational requirements of the process as the desired properties of the biosolids product.”

·         “It is vital that the odor implications also be considered when evaluating process performance.”

·         “…the emerging relationships between process instability and downstream biosolids odor emissions, reinforce the importance of stable operation and good process monitoring and control.”

·         “Stabilization processes which rely on the disinfection of biosolids, such as alkaline or thermal treatment, are heavily influenced by previous sludge handling as the organic content has not been significantly altered during stabilization.”

·         “When wetted and applied to soil, the dried un-stabilized biosolids were judged as the most offensive, presumably due to the production of VFAs and sulfur compounds due to microbial activity on the remaining organic matter.”

·         “the storage or land application of the stabilized biosolids with high organic matter content typically lead to more unpleasant of odors, compared to those which had originally been digested and had lower organic matter contents.”

The Odor Denial Syndrome is far worse than I have acknowledged to myself in the past. It leaves us vulnerable to justifiable public criticism, and it undermines our claim to environmental stewardship.  Odorant emissions are the biggest source of risk to the wastewater profession arising from community, political and regulatory upset. Yet, our industry persistently fails to hold as a central focus in its design of facilities and operations the objective of minimizing odorant qualities of biosolids. New treatment technologies are almost never evaluated for the odor quality of the biosolids they produce. Standard operating procedures at our plants do not generally encompass “best practices” for minimizing odorant formation in the biosolids product.  Public bidding documents for land application services seldom accommodate contractor activities that are responsive to minimizing odor releases, as might be accomplished through responsive storage and application practices.

I propose we fashion for ourselves an alternative narrative about biosolids odors and to genuinely commit to its outcome: we must develop technologies and practices that prevent public odor nuisances.  To do so, we need to be committed to change.  I recently read that “2019 is the year of faux meat,” as start-up companies are successfully introducing the plant-based Impossible Burger and Beyond Burger for those who wish to change their meat-eating habits. With apologies to their marketing gurus, I propose that we have an alternative so incredibly transformational that we can brand our new narrative the Impossible Biosolids.