Biosolids Solidarity

“Solidarity… is the call to embrace the reality that we are bound by bonds of reciprocity.” Pope Francis’s Thanksgiving Day letter,  A Crisis Reveals What Is in Our Hearts, urges us to replace the “personal freedom” ideology with that of the “common good.” A tremendous irony lies in the fact that effective Covid-19 pandemic responses, ones that best protect the community, are actions that have us home alone, but doing so reciprocally, in solidarity with our neighbors.

My awareness of irony has been heightened over these past weeks! The Covid-19 pandemic has erected around me huge, unexpected barriers -- barriers to holidays with families, barriers to running with the trail runners, barriers to singing with barbershop chorus. Yet, the “universe” is bombarding with unexpected messages of connections.  I receive the birthday gift of the novel The Overstory, by Richard Power, in which trees draw a disparate crowd of humans into dramatic life force connections, with the metaphysical idea that nature is seeking to respond to that which humanity requires for survival. When I recommended this book to a natural scientist friend, I am offered in return the 23-year-old Japanese animated film Princess Mononoke by director Hayao Miyazaki, for its theme of how humanity, instead of using destruction, might connect with the forest spirit in mutual respect. This story line recalls for me the miraculous, emerging sciences of forest fungal networks connecting tree species, as in Hidden web of fungi could shape the future of forests, and of the amazing new science of human gut-to-mind connections, as in Your gut is directly connected to your brain, by a newly discovered neuron circuit  and in Parkinson’s disease: Are gut microbes involved?  But making the “connections” even stronger, one of my “go-to” listens while jogging, the On Being podcast, interviewed evolutionary anthropologist Agustin Fuentes, who introduces listeners to the term “holobiont,” which is a theory that “recasts the individual animal or plant (and other multicellular organisms) as a community.“ As Suresh Pillai memorably told me at a WEFTEC long ago, “we are each just a hotel for microbes;” only our vanity has us believe we are one organism. And, on top of this, Pope Francis’s message for Thanksgiving that we act in solidarity to the “invisible pandemics” of refugees and climate change, as these issues connect us, as does Covid-19, across geographic space, among living species, through varying scales of time and dimension.

What is our role as biosolids managers in this call for solidarity in making connections? I have immense pride in public wastewater systems, as they comprise the largest single commitment to environmental stewardship that communities make. Sewers connect people to community, the treatment systems connect food to microbes, the discharge pipes connect restored waters to the river system, and, finally, biosolids connects recovered nutrients to nature.  I enjoy being part of these connections that create value to farmers, soils, and crops, allowing nutrients and carbon to flow in a “virtuous circle.” I am excited to witness the unfurling ingenuity of people crafting new equipment and practices to strengthen the connection within this circle.

The universe’s message that we build connections is one that ought to explicitly drive our biosolids work. Urgent work is awaiting. Deploying all possible nutrients and carbon back to nature is a principle that warrants serious commitment. The compelling article by John Trimmer and Jeremy Guest, Recirculation of human-derived nutrients from cities to agriculture across six continents, shows most urban centers around the globe are proximate to landscapes essential to crop production, and that observed return of nutrients to croplands, rather that disposal to estuaries, was a sustainable practice: “locations with high cropland density, nutrient-intensive crops and compact urban area may find agricultural nutrient reuse particularly impactful and achievable, creating opportunities to boost productivity by coupling urban water and regional agriculture systems.”

Many factors make this recirculation of nutrients and carbon an urgent global imperative, but also a local one.  Pope Francis spoke to “hunger and violence and climate change” as the “hidden pandemic.” In our mid-Atlantic states, vulnerable residents are looking for health and economic solutions to “food deserts” through urban farming, governments are looking to solve water pollution with green infrastructure, and health officials strive to avoid killing heat waves with mitigation of urban heat islands. For each of these initiatives, biosolids is a tool in the toolbox, because biosolids can modify urban soils to restore “ecosystem services” lost during urbanization -- absorbing and filtering storm water, sequestering carbon, and supporting tree and crop growth.

The role of recovered nutrients has a major potential for supporting urban agriculture. The article Resource recovery from sanitation to enhance ecosystem services asserts “We find underexplored potential, particularly relating to the contribution resource recovery could make to regional ecosystems in countries across the globe. Such integrative work is needed to advance knowledge of sanitation–ecosystem linkages and stimulate policy efforts to enhance sustainable development and resource cycles.” The conversation is usually focused on the international level. The article Ending hunger: science must stop neglecting smallholder farmers says that “Policymakers urgently need ideas on ways to end hunger. But a global review of the literature finds that most researchers have had the wrong priorities.” The Pope would admonish us to not ignore the terrible needs in cities, such as Philadelphia, as illustrated in such community projects as Farming Philly and  Grounded in Philly, and to not fail in our support of community initiatives as An urban farm feeding the poorest part of Philly fights to stay alive and growing (Philadelphia Inquirer, 11-24-2020).” Today, these projects currently proceed without the benefit of a concerted effort to recover the carbon and nutrients from local biosolids and food waste.

Urban gardens could be a spectacular location for biosolids product use.  This does not happen without a focused effort, as biosolids products often need to be specially crafted for urban gardens. DC Water has been championing such product development. It has worked with students at Virginia Tech for a number of years, yielding important publications (e.g., Biosolids Improve Urban Soil Properties and Vegetable Production in Urban Agriculture and Biosolids amendments improve an anthropogenically disturbed urban turfgrass system). DC Water has also formed partnerships with landscape supply firms to develop mixes, notably Homestead Gardens. This commercial product development is an extension of horticultural research 30 years ago work by the likes of Elton Smith, A Two-Year Evaluation of Composted Municipal Sludge in the Landscape (1992) and Frank Gouin, Utilization of Sewage Sludge Compost in Horticulture (1993).

Biosolids could be deployed to mitigate the urban heat island effect, simultaneously addressing issues of public health, climate change and environmental justice. Replacing asphalt with trees is a key mitigation measure. The report The role of one large greenspace in mitigating London's nocturnal urban heat island concluded: “Our results lend support to claims that urban greenspace is an important component of UHI mitigation strategies.” Philadelphia was a case study in Avoided Heat-Related Mortality through Climate Adaptation Strategies in Three US Cities; this report showed “In Atlanta and Philadelphia, maximum temperature reductions were achieved through either vegetation enhancement or a combination of vegetation and albedo enhancement.” In the absence of such measures, “relative to base year levels, these 2050 projections represent an increase in heat-related mortality of 55% in Phoenix, 77% in Atlanta, and 319% in Philadelphia.” When Washington DC was evaluated for the potential for trees to reduce urban heat, the report Assessing the Health Impacts of Urban Heat Island Reduction Strategies in the District of Columbia asserted that tree groves can be 9oF cooler than open, grassy areas around them.” The contrast in temperatures of treed landscapes to parking areas is far greater. The article What Is The Urban Heat Island Effect?  explained that temperatures directly under trees can be 20 oF to 45oF cooler than air temperatures in nearby unshaded areas. It is easy to understand, with this contrast, that environmental justice is at play (see Trees as a Pathway for Social Equity). In response to this driver for justice, DC Water’s Bloom is beginning to be deployed for urban tree plantings, with the University of the District of Columbia championing its use.

A third major soil initiative in which biosolids may be deployed in cities is green infrastructure (GI) for reducing stormwater flow and pollutants. A key ingredient to GI is manufactured soils, and many companies working with biosolids-derived soil products are also in the “engineered” soils business. MABA member Denali Water Solutions, through its WeCare Organic group, offers WeCare Engineered Soils.  Casella’s earthlife division offers a wide assortment of engineered soils to meet varying landscape and water management applications. NaturCycle draws upon several dozen biosolids composting facilities in the mid-Atlantic to help soil suppliers meet the exacting specifications for root top gardens, bioswales and other green infrastructure.

Most of these soils products are compost, but DC Water is advancing the deployment of its highly-stable biosolids product Bloom. It is supporting its recommended uses with university research, e.g., Establishing Turfgrass in Poor Soil Conditions using Bloom and  High Quality Biosolids: Assessment of Nitrogen Mineralization and Potential for Improving Highway Soils.

The crafting of such specialty soils has become formalized by such handbooks as the Philadelphia Design Standards, Stormwater Management Guidance Manual v3.2 (October 2020), and the DC Green Infrastructure training program, in collaboration with WEF, with its National Green Infrastructure Certification Program, Body of Knowledge. Truth be told, a bottom-line concern of these standards is long-term maintenance of low soil density and good porosity, soil characteristics associated with low proportions of organic matter use. Specialty soils for GI management of storm water, as defined by these handbooks, are not a large outlet for biosolids.

However, biosolids-based urban soils deserve wider advocacy for its ability to reduce pollutant risks. Biosolids-based soils are under-appreciated for their pollutant sequestration qualities in the urban setting. Soil scientists have shown, for instance, some biosolids composts reducing bioavailable lead and arsenic (High-Iron Biosolids Compost–Induced Changes in Lead and Arsenic Speciation and Bioaccessibility in Co-contaminated Soils). Another article, Management Options for Contaminated Urban Soils to Reduce Public Exposure and Maintain Soil Health, extended the treatment benefits of biosolids to reduced polycyclic aromatic hydrocarbons.  The big picture message by soil scientists is that biosolids has multiple benefits in urban settings. This is well illustrated in Municipal biosolids — A resource for sustainable communities: “Research has shown their value for key components of urban greening including tree, turf, ornamental and vegetable growing, green storm water infrastructure, and reduction in contaminant availability.”

While we recognize many benefits of biosolids used in urban environments, connecting the dots for urban users is difficult. For biosolids manager, “selling” these qualities to the community and with program directors is time consuming and expensive, as DC Water’s Chris Peot and April Thompson can attest, as they work at it daily, and to which I can attest, having worked at it for over two decades in Philadelphia. Yet challenges of climate change, of food and job insecurity, of pollution, and of habitat loss -- challenges Pope Francis referred to as the “invisible pandemic” -- are urgent in our urban centers. We who work with biosolids can embrace the many possibilities of applying biosolids in our cities for the common good, practices that we may justifiably call Biosolids Solidarity.