Northwest Biosolids
2022 Research Round-up

We know that research is one of the things our members most want Northwest Biosolids to prioritize! This round-up gathers the infamous Resource Libraries and Research Short Stories in one place, and captures learning events and the valuable research conducted. Your 2022 membership dues helped to fund all of this and more!  

Resource Libraries- Each month, Dr. Sally Brown provides a review of five research publications in a themed area and helps our members make sense of it all. You need to login to the Information Portal | NW Biosolids, also accessible from our website, before you can view the following.  

Jul. 2021 – More PFAS – This Time in Your Cosmetic Bag  

Aug. 2021 – Biosolids improve soils and so improve the world – Don’t just take my word for it 

Sep. 2021 – How organics can impact soil carbon sequestration and soil health  

Oct. 2021 – More PFAS talk in recent EPA report. Does it make realistic recommendations?  

Nov. 2021 – We Are What We Pass 

Dec. 2021/ Jan. 2022 – Bond Meet Biosolids  

Feb. 2022 – Microplastics are the New Normal  

Mar. 2022 – Masks Off? 

Apr. 2022 – PFAS Yet Again  

May 2022 – Nitrogen – Global Perspective 

Jun. 2022 – Microplastics Yet Again   

Jul. 2022 – Resource Accounting 

Aug. 2022 – Travel Season  

Sep. 2022 – PFAS Everywhere  

Oct. 2022 – Biosolids in the EU  

Nov. 2022 – Char in WWTP?  

Dec. 2022 – Soil Health II 

Research Short Stories
Each month, Northwest Biosolids works to bring you succinct research stories. Below are stories that were shared with the members through the monthly eBulletin that is delivered directly to your mailbox. You can access all of these stories, and many previous years stories, by logging into the Information Portal | NW Biosolids, which is also accessible from our website. 

Jul. 2021 – Dear Dr. Biosolids  I don’t know what to do, we have biosolids that are stinking up our facility… from Something smells rotten in Denmark  

Aug. 2021 – Silver from biosolids accumulates in soil, but overall silver concentrations remain low even after long-term biosolids application – Silver analyses may be used to quantify microplastics in soil  – Dr. Markus Flury, Washington State University  

Sep. 2021 –  Right Now Rain using green stormwater infrastructure – Dr. Sally Brown, University of Washington, featuring Norah Kates, UW graduate/King County 

Oct. 2021 – Can biosolids give a boost to cover crops in dryland, integrated grazing-crop systems?  –  Dr. Deirdre Griffin LaHue, Washington State University  

Nov. 2021 – Northwest Biosolids 2020-21 Research Round-up  

Dec. 2021/Jan. 2022 – Getting a Solid Soil Response to Biosolids… – Kaine Korzekwa, American Society of Agronomy in Treatment Plant Operator 

Feb. 2022 – W4170 Letter  – Natural Resources Conservation Service (NRCS) instituted a program to encourage farmers to use composts and biochar as tools to restore soil health and increase soil carbon reserves. However, they excluded biosolids from the program.  Members of the USDA multistate research group “W4170 Beneficial Use of Residuals to Improve Soil Health and Protect Public, and Ecosystem Health”  (  responded to this exclusion, gaining the ear of the NRCS.  

Mar. 2022 – Assessing anthropod recovery on restored mine sites  – Chantalle Gervan, MSc student,  Thompson Rivers University 

Apr. 2022 – Biosolids reduce compaction and improve water storage in dryland cropping systems – Madeline Desjardins, PhD student, Washington State University  

May 2022 – Impacts of long-term biosolids application on soil compaction and plant available water –  Drs. Navdeep Singh and Gabriel LaHue, Washington State University  

Jun. 2022 – Biosolids Scientist Updates | NW Biosolids a Tribute to Al Page – the godfather of the EPA 503 regulations – Dr. Sally Brown, University of Washington  

Jul. 2022 – Biosolids as a Sulfur Nutrient Source | NW Biosolids – Dr. Amber Moore, Oregon State University  

Aug. 2022 – Current Research Evaluating the Threat of PFAS to Land Application – Dr. Ian Pepper, University of Arizona  

Sep. 2022 – Compost and Community Gardens – Dr. Sally Brown, University of Washington 

Oct. 2022 – The Passing of the 1972 Clean Water Act Started us Down the Biosolids Beneficial Use “Road”: How Did We Get Where We are Today?  – Drs. James Ippolito and Ken Barbarick, Colorado State University  

Nov. 2022 – An Update from the Field: Activities at WSU’s Long-Term Biosolids Trials – Madeline Desjardins, PhD student and Dr. Deirdre Griffin LaHue, Washington State University  


Events – Supported through Northwest Biosolids research funding 

Soils 101 – 2 cohorts completed  
Six-part classroom series with Dr. Sally Brown. Course syllabus: Biosolids are applied to soils at rates to meet the fertilizer demands of crops. To really understand what all the fuss is about – both good and bad, it helps to have a basic understanding of soils and soil processes.  

Risk Assessment in the Era of PFAS – 5 cohorts completed  
A three-part course with Dr. Sally Brown. Course syllabus:  Forever chemicals are now front and center for everyone’s concerns about biosolids. These follow in a long line of concerns ranging from metals to toothpaste residue. It almost makes you wonder if biosolids are really safe. This series goes over: the basics of risk assessment including an analysis of different pathways for contaminants to cause harm; dives into PFAS including their structure, their history, their presence in the environment, and their behavior in biosolids; and, different ways to communicate what the science says- to regulators, stakeholders, people within your division, and the general public.  

 Biosolids 101  
A crash course featuring a panel of seasoned professionals from across the spectrum specialized in regulations, research and program management. Panel: Dr. Sally Brown (University of Washington), Dr. Deirdre Griffin LaHue (Washington State University), Henry Campbell (Biosolids Program Manager, King County) and Dr. Dan Thompson (Division Manager, City of Tacoma).  

Research Study Updates  

Urban agriculture – Dr. Sally Brown, University of Washington 
This King County-NW Biosolids co-funded study is a multi- year research project testing the use of amendments on urban soils. The changes in a range of soil parameters reflective of soil health as well as vegetable yield and nutritional content were measured. This work involved both a multi-year field trial and a greenhouse study. As a companion to this work, a survey of community gardens in the Harvest Pierce County program was conducted. The size and number of plots in over 60 gardens were measured and each plot was ranked for intensity of use. In addition to the Harvest Pierce County survey, a survey of community gardens in King County was completed. Unlike the Pierce County gardens, the gardens in King County are managed by multiple programs, are not provided with materials to amend soils, soil testing or guaranteed access to building materials, education and irrigation water. The survey of the Harvest Pierce County program was published in a peer review journal. The information from both the King County survey and the Harvest Pierce County survey are used in an additional publication that is currently being prepared for submission; this manuscript focuses on the impact of resource recovery through food scrap composting and beneficial use of biosolids for growing vegetables in urban gardens. 

Quantifying use in a community garden program with extensive resource provision to gardeners – Niedzwiecki, Alexandra, N. Kates, S. Brown, K. McIvor, 2022. Urban Agriculture & Regional Food Systems. 

How does your garden grow? Impact of residuals-based amendments on urban soil health, vegetable yield and nutritional density – Una, Toby, J. Hernandez, A. Beebe, S. Brown, 2022. Urban Forestry & Urban Greening. 

Forest nutrient dynamics – Dr. Sally Brown, University of Washington 
Biosolids application rates in the forest have been limited by the guidance from WA Department of Ecology that applications should not result in elevated nitrate concentrations in groundwater below application sites. For agricultural soils, the nitrate level of concern is 10 mg/L, whereas guidance for forest sites was no increase over background. When biosolids are added to a site, the nitrogen will be in a slow-release form. Carbon will also be added to the site soils. While the C:N ratio of the biosolids is low (8:1 – 11:1), the biosolids may increase above and below ground plant growth to somewhat narrow this ratio. 

There is a large amount of data that has been routinely collected by the King County Forestry program that may help to determine if concerns over nitrate movement to groundwater are warranted. In 2022 Emma Leonard, MSc student, set-up a data set from all available records of King County’s Forest applications. The data set includes information on time of sampling, depth of horizons, locations of units, soil series, and total C and N where available. Emma is currently creating a multi-layered GIS map of the data and will be able to start statistical analysis when it is complete. Emma is working closely with Ben Axt (King County) and Dr. David Butman (University of Washington) on this project.   

The research will offer additional information on soil nitrate in relation to biosolids fertilization for commercial tree plantations. Because the current recommendations from WA Department of Ecology is to limit applications so that there is no observable increase in groundwater nitrate, this has limited both frequency and rate of biosolids applications. The data from this research will provide a more quantitative relationship between the different factors involved in soil nitrate and may provide information that can alter how biosolids are applied to forest lands. 

Carbon balance for biosolids use in commercial Douglas Fir plantations in the Pacific Northwest – Leonard, E. J. Bodas, S. Brown and B. Axt.  2021.  J. Environ. Manage.  

Biosolids as a Tool to Improve Soil Health – Soil Health Institute project – Dr. Deirdre Griffin LaHue, Washington State University
In 2019, the long-term biosolids research site “GP-17” located in eastern WA was selected to participate in an international study evaluating soil health across North America (United States, Canada and Mexico). There are over 120 different research sites participating in this study, including one other biosolids site located in Colorado. The study compares research sites that have been managed uniformly over a long period of time. GP-17 is being compared to other conventionally managed sites using different treatments of crop rotation, compost and manure addition, and cover cropping etc. Major findings demonstrate that long-term biosolids applications have substantially improved physical, chemical, and biological soil properties. Farmers count on stored soil moisture to help their crops grow, and organic matter additions from biosolids can help to make the soil hold on to more water, like a sponge. Results from this study show that biosolids applications have indeed increased available water holding capacity, which is likely one reason that crop yields have been higher in these treatments compared to unfertilized and fertilizer controls.  Madeline Desjardins (PhD student) and Dr. Deirdre Griffin LaHue are in the late stages of writing the manuscript in collaboration with Dr. Jim Ippolito, who leads the long-term biosolids site at Colorado State University. Stay tuned for their peer reviewed publication 

Soil Health Institute North America project papers:  
Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage – Rieke, E.L., S.B. Cappellazzi, M. Cope, D. Liptzin, G.M. Bean, K.L.H. Greub, C.E. Norris, P.W. Tracy, …., A. Bary, …., D. Griffin-LaHue, et al. 2022. Soil Biol. Biochem.

An evaluation of carbon indicators of soil health in long-term agricultural experiments – Liptzin, D., C.E. Norris, S.B. Cappellazzi, G.M. Bean, M. Cope, K.L.H Greub, E.L. Rieke, P.W. Tracy, …, A. Bary, …, D. Griffin-LaHue, et al. 2022. Soil Biol. Biochem.   

Carbon‐sensitive pedotransfer functions for plant available water – Bagnall, D.K., C.L.S. Morgan, M. Cope, G.M. Bean, S.B. Cappellazzi, K.L.H. Greub, D. Liptzin, C.E. Norris, E.L. Rieke, P.W. Tracy, …., A. Bary, …., D. Griffin-LaHue, et al. 2022. Soil Sci. Soc. Am.

Biosolids, Cover Cropping, and Grazing for Synergistic Soil Health Benefits – Dr. Deirdre Griffin LaHue, Washington State University 
This research site was established in 2020 in Douglas County, WA to investigate potential benefits and interactions of biosolids combined with cover cropping and integrated livestock grazing of cover crops. Investigating and quantifying synergistic benefits of biosolids and cover crops in dryland cropping systems will give more evidence of the value that land application of biosolids provide to farms. This could lead to increased demand for application sites in these areas. Soil analysis from 2021 showed that at every depth, biosolids increased nitrate-N compared with the fertilized and no fertilizer control. This was true in both the grazed/cover cropped and ungrazed/non-cover cropped areas. Similar trends for soil ammonium-N and soil phosphorus were also noted. This site was fallowed in 2021-2022, however the team still collected soil samples in May 2022, as well as weed biomass samples. Sample analysis is currently underway by Madeline Desjardins (PhD student).  

Accumulation of microplastic and nano particles from biosolids in agricultural soils – Dr. Markus Flury, Washington State University
This is an ongoing study with major funding coming from the USDA National Institute of Food & Agriculture.  While there is a wealth of information available about microplastics in aquatic ecosystems, there is very little known about microplastics in terrestrial ecosystems. In 2022, soil samples were analyzed using various methods to identify microplastic particles. A new instrument LDIR (Laser Directed Infrared Image Analysis System) was also trialed and allowed for quantification of the number of plastic particles (which is extremely difficult), identification of individual particles, and to determine particle shape and size. Currently, there is only one university in the US that has such an instrument and WSU is hoping to secure access to it to advance their study. Experiments were also started to investigate how plant roots interact with plastic particles. Two model plants, Arabidopsis thaliana and Triticum aestivum (wheat) are being used to test whether plastic particles can be taken up by the roots; model plastic particles (fluorescent microbeads) are being used. Plants are being grown in culture (Petri dishes and agar) and visualization of root-plastic interactions is done with microscopy. Roots will also be taken from wheat plants grown at the Douglas County field site to see whether plastics from biosolids will interact with wheat plant roots. 

Arizona Water & Energy Sustainable Technology Center (WEST Center) – Dr. Ian Pepper
The concern over the potential for groundwater contamination from PFAS following land application of biosolids and subsequent leaching, has raised the possibility of a national ban of land application. The “National Collaborative PFAS Project” was initiated to answer the question: “Is land application of biosolids a significant source of PFAS exposure via groundwater contamination?” The objective of this study is to develop a methodology to evaluate site specific land application sites for their potential to contaminate subsurface groundwater with biosolids derived PFAS analytes. The project will: evaluate incidence and mobility of PFAS in soils following land application of biosolids; sample sites across the US (up to 30 sites); sample groundwater beneath each site to create paired data sets of soil and groundwater PFAS concentrations; and, input data into a screening level risk assessment model to evaluate risk of PFAS leaching into groundwater. NW Biosolids contributes annually to the WEST Center and this year’s contribution went fully toward funding this project. 


Research Publications (July 2021 – Dec 2022) that received support from Northwest Biosolids in a previous research funding cycle. 

Fertilizing with BiosolidsSullivan, D.M., A. Tomasek, D. Griffin-LaHue, E. Verhoeven, A.D. Moore, L.J. Brewer, A.I. Bary, C.G. Cogger, D. Biswanath. 2022. Pacific Northwest Extension  

Biosolids and conservation tillage for rainfed wheat farming in dry Mediterranean climates Schillinger, W.F., Cogger, C.G., Bary, A.I., 2022. Soil & Tillage 

Biosolids processing effect on sulfur plant availability – Moore, A.D., Smith, E., Bary, A., Sullivan, D.M., 2022. Soil Sci. Soc. Am. 

Tools to quantify the potential for phosphorus loss from bioremediation soil mixturesKates, N., D. Butman, F. Grothkopp, and S. Brown. 2021.  Tools to quantify the potential for phosphorus loss from bioretention soil mixtures.  J. Sustainable Water Built Environ 

*At Northwest Biosolids we are in the process of switching our fiscal year to the calendar year and our research cycle is following suite, as such this publication covers more than 12 months.