If you have lived in Whatcom County for more than a few months, you’ve probably experienced the “odeur de manure” that periodically wafts through our air — reminding us that we are a very agricultural community. Spreading animal manure on cropland is a centuries-old technique that helps to reclaim nutrients and keep our soils rich and fertile. Is it a stretch of the imagination, then, to get the same benefits by spreading human manure onto our cropland?
Perhaps not — about 50 percent of the sewage solids in Washington state are already being processed into a type of compost called biosolids and applied to local soils. The city of Bellingham is getting ready to make major changes to the Post Point Wastewater Treatment plant so it too can process our sewage solids into biosolids that will be spread on the land where we grow our food.
Besides the initial ick factor, on the surface, this practice appears to be a good idea.
This new plan calls for replacing the old, fracked gas-burning sewage incinerator with an anaerobic digester. Here, microbes will break down the sewage sludge into nutrient-rich biosolids, which the city seeks to sell to a third party company. The company will further process and sell the product as Class A biosolids that can be used anywhere, without restrictions, from personal gardens to industrial agriculture. In addition, methane from the microbes’ industrious waste-eating — which would otherwise be a potent greenhouse gas — will be captured from the digester to help power the digester and other areas of the treatment plant.
It sounds wonderful — a system that turns waste into something that puts food on the table, without pumping out climate-heating gases. But, unfortunately, there is more to the story.
Chemicals Found in Sewage Sludge
Our solid waste consists of a lot more than just beneficial nutrients. Think about all the soaps, cleaners, pharmaceuticals and more that we also put down the drain. In fact, thousands of chemical contaminants have been identified in sewage solids including: 27 metals, PFAS (per- and polyfluoroalkyl substances, which are human-made chemicals that don’t break down in the body and are linked to cancers, low birth weights and other health concerns), microplastics, flame retardants, pesticides, personal care products, pharmaceuticals, and hormones. (1,2,3)
All of these chemicals are persistent, meaning they don’t easily break down, and they build up in the food chain. They are toxic and exposure to them can lead to a variety of illnesses including respiratory and cardiovascular disease, cancer, reproductive effects, nerve and neurodevelopmental effects, endocrine disruption or immune system dysfunction, and organ damage in humans and animals. (3,4)
Contaminants Travel to Food Web
When sewage solids are applied to land, the chemicals do not stay put — they are suspended by wind, washed into streams with rain, migrate deeper into the soil, seep into groundwater, and are absorbed by plants and the animals that graze on them. It is impossible to fully understand how thousands of different chemicals will travel and react in a wide variety of soil types and weather conditions — there are just too many combinations to study.
There is, however, an abundant amount of research showing that chemical contaminants are found in the roots, stems, leaves, fruit and seeds of plants grown in sewage solids — even in earthworms living in sewage solids. (5,6) In fact, these contaminants can travel throughout the terrestrial food web, which humans are a part of. (7,8)
Source Control Is Not Fast Enough
It is critical that we stop putting these chemicals into our environment in the first place. But, with thousands of different chemicals that need to be removed, reduced, or replaced, this cannot happen quickly enough. Many of these contaminants are persistent and accumulative. Even if we stopped producing them today, we would still find them in our environment decades later.
A case in point: in 1979, the EPA banned polychlorinated biphenyls (PCBs), yet PCB levels in many Puget Sound English soles, herring, and Chinook salmon are dangerously high and still increasing in some cases, even 30 years later. (9)
There are currently 195 bodies of water in Washington state (including Lake Whatcom) that are listed as impaired by PCBs. (10) This illustrates how difficult it is to remove these chemicals from our environment even when they are no longer in production. PFAS, flame retardants, microplastics, and many pharmaceuticals likely in biosolid composts also behave in this manner.
There’s No Clean Soil Act
How is it possible for these toxic biosolids to be legal in our state? Rampant unregulated pollution led to the creation of both the Clean Water Act and the Clean Air Act in the 1970s. Both of these rules were pivotal in cleaning our waterways and our skies, but had some unintended consequences. The toxics scrubbed and filtered from water and air, while no longer being discharged into our environment, are now concentrating in our soils. Because there is no Clean Soil Act, there is little to no regulation in what we dispose of in our soils.
The water that is pumped out into Bellingham Bay from the Post Point Treatment Plant is definitely cleaner now, thanks to recent renovations to the plant and consistently meets all the guidelines of the Clean Water Act. We now have a concentrated substance that is rich in nutrients, and undoubtedly makes an effective fertilizer, but is also rich in contaminants that come from people’s houses, businesses, industries, and streets. The plan for Post Point cannot break down these hazardous chemicals.
Testing and Reevaluation
Current biosolids’ regulation only requires that facilities test for nine metals, no other contaminants are measured or monitored — as there is no Clean Soil Act. After insistence from community members, the city has agreed to run initial tests on the solids for toxic contaminants. Testing for these chemicals may not only be the best course of action for community health, but soon it may also be required legally. New regulations for PFAS are currently being developed at the state and federal levels which could impact the usability of Post Point biosolids. If these biosolids exceed a certain amount of PFAS, they may not be given the stamp of approval to be applied on land.
This wastewater treatment project is not cheap nor simple — the city reported that building the anaerobic digester would cost about $200 million, plus $400-500 million for new nutrient management technologies. Before making any expensive upgrade, the city should investigate new technologies that keep nutrients out of our water, keep sewage fees affordable, and meet the demands of a growing region while also breaking down toxic contaminants.
Other countries and U.S. cities have chosen safer, more environmentally responsible technologies to manage their solid wastes. Bellingham should follow suit. Just recently, Edmonds, Washington, announced that it is going to build a gasification unit for their anaerobic digester that will burn their biosolids (a process that breaks down toxic chemicals) instead of land-spreading them. Gasification not only meets the requirements in the Paris Agreement for reducing greenhouse gasses, but it also yields beneficial nutrients that can be safely applied to land.
How to Get Involved
The city of Bellingham currently has a survey that asks community members to voice their opinions and concerns about the anaerobic digester — please fill out the survey: https://engagebellingham.org/resource-recovery. In addition, you can email Robert Johnson, the Project Manager (firstname.lastname@example.org), City Council (email@example.com), or Mayor Seth Fleetwood (firstname.lastname@example.org) with your questions or concerns.
As state laws evolve and become more protective, we have an opportunity to be a leader in sewage solids management by thorough testing and responsible handling of our solids.
1. EPA. 2009. Targeted National Sewage Sludge Survey Sampling and Analysis Technical Report. EPA-822-R-08-016. Retrieved from: https://www.epa.gov/sites/production/files/2018-11/documents/tnsss-sampling-anaylsis-tech-report.pdf.
2. Chad, A. et al. 2006. “Survey of Organic Wastewater Contaminants in Biosolids Destined for Land Application.” Environmental Science & Technology 2006 40 (23), 7207-7215. DOI: 10.1021/es0603406.
3. EPA. 2018. “EPA Unable to Assess the Impact of Hundreds of Unregulated Pollutants in Land-Applied Biosolids on Human Health and the Environment.” Report No. 19-P-0002. Retrieved from: https://www.epa.gov/sites/production/files/2018-11/documents/_epaoig_20181115-19-p-0002.pdf.
4. Yu, M. et al. 2011. Environmental Toxicology: Biological and Health Effects of Pollutants, Third Edition. CRC Press. 397 pp.
5. Wu, C. et al. 2010. “Uptake of Pharmaceutical and Personal Care Products by Soybean Plants from Soils Applied with Biosolids and Irrigated with Contaminated Water.” Environmental Science & Technology 2010 44 (16), 6157-6161. DOI: 10.1021/es1011115.
6. Kirkham, M.B. 2020. “Water Relations and Cadmium Uptake of Wheat Grown in Soil with Particulate Plastics.” Particulate Plastics in Terrestrial and Aquatic Environments. CRC Press. 442 pp.
7. Kinney, C.A. et al. 2008. “Bioaccumulation of pharmaceuticals and other anthropogenic waste indicators in earthworms from agricultural soil amended with biosolid or swine manure.” Environmental Science and Technology, v. 42, no. 6, p. 1863-1870, doi:10.1021/es702304c.
8. Jessica J. et al. 2016. “Occurrence of Triclocarban and Triclosan in an Agro-ecosystem Following Application of Biosolids.” Environmental Science & Technology 2016 50 (24), 13206-1321. DOI: 10.1021/acs.est.6b01834.
9. West, J.E., O’Neill, S.M. & Ylitalo, G.M. “Time Trends of Persistent Organic Pollutants in Benthic and Pelagic Indicator Fishes from Puget Sound, Washington, USA.” Arch Environ Contam Toxicol 73, 207–229 (2017). https://doi.org/10.1007/s00244-017-0383-z.
10. Department of Ecology. Washington State Water Quality Assessment & 303(d) list. https://ecology.wa.gov/Water-Shorelines/Water-quality/Water-improvement/Assessment-of-state-waters-303d.
Kirsten McDade is the pollution prevention specialist at RE Sources, a local nonprofit organization working to protect the environment of the central Salish Sea Region. She holds an M.S. degree in Ecology and takes a science- and community-based approach to protecting the place where she lives.