The consensus among scientists is that a planetary emergency threatens all present and future generations (Climate Endgame: Exploring catastrophic climate change scenarios). Ours is a species with a human-carbon nature out of context with Earth’s capacity to withstand GHG emissions and resource extraction.  Our future will inevitably be defined not by expansion but by contraction, and we must learn to reduce our “take” from Nature and increase our “give” in terms of energy and natural resources (An Inconvenient Apocalypse: Environmental Collapse, Climate Crisis, and the Fate of Humanity).  We can do all of this, if in a modest way, with biosolids.

Our global response to the climate challenge is to reduce depletion of resources by directing waste back  into production – a practice that is now called the Circular Economy. A circular economy reduces the amount of waste produced by creating valuable products out of traditional waste streams.  Water resource recovery facilities (WRRFs), at the confluence of carbon, nutrient and water flows, can directly contribute to a circular economy by producing clean water, nutrients, renewable energy, and other valuable bio-based materials from wastewater.  The reduction of resource extraction directly connects to steps needed to reduce emissions of climate changing gases (The role of the circular economy in climate mitigation). 

Our professional organizations are taking on the circular economy. WEF has announced: “We must expand water’s role in the circular economy,” and the US Water Alliance promotes “Net Zero” emissions.  We hold up examples in our very own region of public agencies recovering nutrients and energy. Hermitage Food Waste to Energy Facility in western Pennsylvania has deployed its robust two-phase thermophilic anaerobic digesters to become a central processor for commercial food wastes, selling substantial electricity back to the grid.  Rahway Valley Sewerage Authority in New Jersey is in partnership with Waste Management to accept an “engineered bioslurry” into its anaerobic digesters, powering large internal combustion engine generators, and deploying waste heat to make a dried biosolids soil product. Phosphorus extraction from centrate is underway at Hampton Roads Sanitation District in Virginia Beach and in York County, Pennsylvania, using the Ostara PEARL process to produce a granular struvite fertilizer.  Landis Sewerage Authority in Vineland, New Jersey, is the region’s “greenest” WRRF, with not only enhanced biogas and electricity generation from high strength organic waste acceptance, hosting wind generators and solar PV panels, engaged in aquifer injection of its effluent,  and biosolids use on agency-owned farm fields – a full recycling of nutrients, carbon and water. 

The Intergovernmental Panel on Climate Change issued its Working Group III 2021 report Mitigation of Climate Change. Among the many practices in this 3,000+ page report is the capture of carbon in soil and biomass. We practitioners know that biosolids is a meaningful ingredient for doing so. The newly released BEAM 2.0 (Biosolids Emission Assessment Model) is a tool available to WRRFs to plan for and to select treatment technologies and biosolids use projects that best respond to the urgent need to respond to the IPCC challenge.  

Ranking well as a technology for GHG mitigation in BEAM is composting. Composting has shown itself to be a robust and resilient technology for biosolids processing. It is available at all scales and has been proven over many decades to build soil, replace fossil fuel-based fertilizers, and support local agriculture.  WRRF compost plants and merchant plants in Virginia (McGill), Maryland (Veolia), Pennsylvania (JP Mascaro), New Jersey (Denali) and New York (Denali) have for nearly 40 years supplied biosolids-based soil products to mid-Atlantic customers, and new facilities are under development in eastern Pennsylvania (McGill) and southern New Jersey (Synagro).  Importantly, compost is an ingredient in engineered soils that are useful in the “green infrastructure,” helping cities manage increased stormwater and rising urban heat. That biosolids compost can be applied to a variety of soil and biomass improvement projects is a factor in its importance in the circular economy.

Biosolids is a potential ingredient in land restoration,  a major category of climate mitigation actions.  Researchers in soil health, land rehabilitation and ecosystem restoration have studied the field-scale results of biosolids use, thereby lending credibility to its use in climate mitigation projects.  A sound research basis is necessary for biosolids to be part of the vibrant, emerging international Voluntary Carbon Market to accomplish greenhouse gas reductions. This is through a system of protocols accepted by financial markets for Nature-Based Solutions (NBS) for Carbon Management.  Protocols have been issued in recent years as a foundation for NBS , such as the American Carbon Registry for carbon accounting, the Verra Soil Carbon Standard, and the Carbon Action Reserve Soil Enrichment Protocol.  

The precise role of biosolids in soil carbon is still a matter of scientific discussion. While soil scientists explore new avenues of inquiry into soil carbon biochemistry, and while the fate of the carbon fraction of biosolids may still not be fully understood, less subject to debate is the field results of biosolids used to support bioenergy crop production on disturbed landscapes. The work of Sylvis Environmental at its BIOSALIX project in Alberta, Canada, is seminal for its focus on soil carbon and biomass production.

In the heavily urbanized Mid-Atlantic region, thermal conversion processes seem to be drawing entrepreneurial talent and public agency champions. The element of the circular economy ethos at play here is the embrace of technology that optimizes for thorough elimination of waste hazards, capture of pure water and elements, and output of useful products. Thermal processes follow along a gradient of increasing temperatures and pressures, with or without water as a matrix, accomplishing destruction of organic micropollutants (perhaps even recalcitrant ones in the PFAS group), elimination of microorganisms (including pathogens), production of sterile water and salts, and, in some technologies, yield of a char or biochar that can be applied beneficially for soil health improvement. 

A wide array of first-of-a-kind thermal projects are close to home in the Mid-Atlantic.  Somax Circular Solutions (hydrothermal carbonization) is under construction in Pottstown, PA.  Bioforcetech (biodrying and pyrolysis) is under construction at Ephrata Borough.  Ecoremedy completed a gasifier demonstration in Morrisville, PA, and moved its equipment to the state of Washington.  Aries Clean Technologies remains hopeful it will soon complete its gasifier at the Linden-Roselle WRRF in New Jersey.  EarthCare is developing a merchant gasifier in Bethel, PA, fed by animal rendering wastes as well as WRRF solids.  Biowaste Pyrolysis Systems is in a shake out period for its Schenectady (NY) installation. On the West Coast U.S., 374Water is underway with a project in Orange County, CA, and Genifuel has a hydrothermal liquefaction demonstration facility at Metro Vancouver, BC.  Should any one or more of these ventures prove successful, a transformative circular economy technology will likely be embraced by WRRFs nationwide, and especially in the mid-Atlantic. 

The key to altering humanity’s course on climate change and greenhouse gas emissions is to win the broad collaboration of the public and business enterprises (A public information campaign on the climate crisis is urgently needed).  Jonathan Safran Foer, the author of We Are The Weather, quips that “the planetary crisis hasn’t proved a good story. It not only fails to convert us, it fails to interest us.”  We practitioners in biosolids management have the same dilemma: wastewater, like climate change, is an aspect of daily experience in which all humans participate, but about which no one really wants to be reminded.  Communication specialists have suggested that the problem needs to be discussed in small pieces, with a local angle, with an invitation to participate, and with a message connecting to the big picture (SUFFICIENCY ECONOMY Envisioning a prosperous descent).  In that regard, social media posts are very popular for #compost, #urbanfarming, and #cleanwater, but not for #biosolids. 

Biosolids goes beyond the circular economy when it connects to local projects that make a difference today for people where they live. Yes, biosolids are meaningful in the very large global view of climate change when they decrease fossil fuel use, mitigate greenhouse gases, and sequester carbon. Yet our role may be more immediate and imaginable.  Biosolids soil products can be offered to communities as a “circular economy” tool for planting tree-covered heat islands, installing rain gardens for managing extreme storms, upgrading urban soils to the effects of drought and building soils for sustainable local food production.  Biosolids is THE manifestation of the “circular economy” at work today in many communities.  We need to celebrate and tell this as our primary message of biosolids management. 

Bill Toffey has over 40 years’ experience in municipal wastewater, environmental and energy management. He is the principal of Effluential Synergies LLC, a sustainable residuals consultancy, and until the beginning of 2022 served as the Executive Director of the Mid Atlantic Biosolids Association, a trade group that covers seven states and supports an industry with 800 biosolids generators and 1,800 biosolids practitioners. 

To view the MABA September 2022 Webinar: Beyond the Circular Economy: Framing Biosolids Recycling at The Food-Energy-Water Nexus, with Bill Toffey presenting, visit https://youtu.be/Ol4-gyBWMpo