MidAtlantic Biosolids Association

Research Update from Sally Brown, University of Washington

Mega Carbon Effect of Biosolids

Let’s step back a few (000 000 000 000) zeros and, instead of thinking in parts per billion/ trillion that require specialized equipment and several days of chemical extraction, to thinking of stuff you can pretty much see with your naked eye.  Let’s measure in tons (1 kg x 1000) instead of ppb (1 kg x 10-000000001).  It is this perspective that lets you see the value of the material.  Yet again, let me remind you all that we work with some excellent sh**t!.  The library this month will focus on how biosolids improve soils and so improve the world.  I say this not just as a soil scientist.

We start with a meta-analysis that looked at a wide range of studies to come up with an estimate of how much carbon you add (persistent over time) to the soil following biosolids applications. (Paper #1: Carbon sequestration value of biosolids applied to soil: A global meta-analysis ). Here is the take home:  3.3% increase in soil carbon per hectare when you add 100 Mg of biosolids.

That is a lot of added carbon.  Soil weighs 1000 tons per acre and has an initial C concentration of approximately 2%.  When you add biosolids and get the soil carbon up to 5%., you achieve an extra 30 tons of elemental carbon or 110 tons of carbon as CO2 equivalent per acre. 


The paper has qualifications.  Different soil types, temperature and moisture regimes will get different results in total added soil carbon. But the main point is that biosolids additions can result in a remarkably high rate of carbon storage.  Note that Northwest Biosolids research dollars funded at least one of the cited studies.

Paper #2 (Carbon balance for biosolids use in commercial Douglas Fir plantations in the Pacific Northwest) is local, fresh off the press and confirms the findings of Paper #1.  Here we looked at soil carbon sequestration in forest plantations where King County has been applying LOOP biosolids cake for decades.  We looked at two soils, at sites miles apart from each other, both planted in Douglas Fir.  In the soil with higher carbon to start with, we saw no increased carbon storage from biosolids applications.  In the site with lower soil carbon storage, we saw quite the opposite.  The figure says it all.


Note that the average here is pretty similar to the average seen in Paper #1.

Paper #3 is another meta-analysis (Revegetation of degraded ecosystems into grasslands using biosolids as an organic amendment: A meta-analysis).  Here the focus is on whether biosolids works well to restore native grasslands.  Increasing soil carbon is a necessary first step to this process, but it gets more complex when you consider plant species richness and other factors.  They found across the 59 studies they reviewed that biosolids were highly effective at increasing plant cover and productivity.  Species richness (the variety of types of plants) did not change.  Biosolids worked best in warmer places, and seeding increased plant cover more quickly than not seeding.  They also found that biosolids were less effective if used to restore a burned area.  All responses were reported as the ratio to the control.  Key figure from the paper are shown in this figure below.


The final two papers are also focused on biosolids applied to grassland.  They each focus on a distinct site. They both use a range of measures to evaluate soil health.  Both come from Jim Ippolito, a professor at Colorado State.  In Paper #4 (Long-Term Biosolids Applications to Overgrazed Rangelands Improve Soil Health), the focus is on a degraded rangeland and either on a single high rate (30 Mg ha) or on multiple lower rate applications to the rangeland.  One and done is the best approach.  Biosolids applied once at the higher rate were more effective than multiple applications at lower rates for the soil chemical properties (hear that, regulators?).  However, the lower rate over time was better for the biological indicators.  Overall, the authors say that applying up to 30 Mg ha, with an optimal rate of 10 Mg ha is what you need to restore a grassland. 

The last paper (Long-term biosolids land application influences soil health) uses the same soil health tools to look at the impact of biosolids on dryland wheat, another type of grassland.  The study was based on a long-term trial in Colorado.  Jim presented the preliminary results at a Biofest a few years back.  The field was tilled, most likely minimizing improvements in physical properties and also likely reducing carbon sequestration.  Nevertheless, the biosolids were the winner over synthetic fertilizer.  This figure gets you the key points and is very easy to follow.


What these papers show is that, despite the ppb of PFAS or whatever people are tearing their hair out about at the moment, biosolids are a highly effective tool for restoring soils, by adding carbon back into the system and, as a consequence, by improving the health and diversity of those ecological systems.  That is the take home message. 


Getting a Handle on Biosolids

Dr. Malcolm Taylor is the prime thought leader of this TOPIC, and I have thereby named the index introduced here in his honor, the Taylor Handleability Index for Biosolids, or THIB.  With his employer WSSC Water nearing completion of its solids treatment system, Taylor took on the long-overdue mission of ensuring that his agency’s Class A EQ biosolids would be beautiful, or at least handleable.  While we each might have an intuition that a material that is too sticky, too clumpy, too hard, or otherwise difficult to handle and clean up could not reasonably be a marketable product. But this intuition needs to be set to some specific attributes that can be defined and numerically expressed.

The aspects of handleability on which Taylor established a score of handleability are Friability, Stickiness, Smear, Stain and Dustiness. He developed a scoring matrix, with numeric ratings one to four for each of these five characteristics. The arithmetic sum of the score of each aspect produces the overall handleability score for the biosolids product, with a rating of 5 being very poor and a rating of 20 very excellent.

The five aspects of handleability are not without precedent in wastewater or in other situations in society. Friability is a familiar concept in soil characterization, as explained in the entertaining YouTube video Soil Friability Test. While friability is mostly a good attribute with soil and biosolids, it is not so good in the pharmaceutical industry (think aspirin tablets) or in the food industry (think crackers). 

You might think Stickiness as a particularly subjective attribute, but in fact a branch of material science is devoted to it (Stickiness – A Comparison of Test Methods and Characterisation Parameters).  The Wikipedia entry for Post-it Notes describes Dr. Spencer Silver’s world-changing invention of this "solution without a problem,” illustrating the keen importance of stickiness.

While most of the Smears these days seems to be of a political sort, this term of art covers enormous ground, from blood smears and PAP smears in medicine, to clay smears in geology, to fecal smearing in child psychology. The Merriam-Webster definition of smear is particularly satisfying: “viscous or sticky substance and a spot made by or as if by an unctuous or adhesive substance.” I had to look up “unctuous.” Unctuous means greasy or soapy, and I believe we need to be using this in our professional terminology, as in “this is unctuous biosolids.”  

Stains are well known by all of us at work and home, and I have had my share of biosolid stains. But the recent Malcolm Gladwell “Revisionist History” podcast Laundry Done Right illustrated to me how stains motivate a multi-billion-dollar industry. This podcast described the work of the P&G’s Fabric and Home Care Innovation Center to produce effective stain removal in cold-water washing; we all need the Instant Stain Remover and follow #TurnToCold on social media.

Dustiness is a feature of biosolids products about which I devoted an entire TOPICs, Dust to Dust (3-20-2021). Noting that dustiness for manufactures of chemical fertilizers, animal feed and wood fuel pellets is a very big deal, I suggested that we should also regard dustiness as a big deal.  We could all go out and buy on Amazon a “Two Compartment Pellet Durability Tester”  which produces a numeric reporting of dust produced during a specific simulation of transportation handling. And, we could buy a supply of DUSTROL® or GALORYL® dust control coating for coating particles to reduce dust production.  

With this “grounding” in the five key aspects of HANDLEABILITY, here is the no-nonsense proposal from Malcolm Taylor for a transformative measure of biosolids quality, one that could become a breakthrough for our profession, at long last, for our properly characterizing biosolids products suitable for distribution and marketing: the THIB!

Taylor Handleability Index for Biosolids (THIB)

Friability - The tendency to break into smaller masses with some deformation prior to rupture and ability of material to cohere again when pressed together. For evaluation material is gently kneaded in an open fist and then allowed to sift between open fingers.





Material easily breaks apart into small uniform aggregates and maintains a loose granular nature that sifts easily through fingers without clumping  


Somewhat friable

Material will break apart into aggregates of varying sizes with clumps that requires additional force to break up


Marginally friable

Material will break apart into fragments but requires significant force and large clumps must be broken up individually


Not Friable

Material is very difficult to break into smaller clumps either because it is severely hardened or muddy and deforms without breaking apart.

OR: When gently kneaded in an open fist, material rapidly breaks apart into fine dust and maintains little to no aggregation  


Stickiness - the quality of adhesion to other objects. For evaluation, material is pressed between thumb and finger and its adherence noted using the following scale when pressed between the thumb and finger. 





After release of pressure, practically no material adheres to thumb or finger


Slightly sticky

After pressure, material adheres to both thumb and finger, but comes off one or the other rather cleanly



After pressure, material adheres to both thumb and finger and tends to stretch somewhat and pull apart rather than pulling free from either digit


Very sticky

After pressure, material adheres strongly to both thumb and forefinger and is decidedly stretched when they are separated


Smear:  The tendency for a material to smear and leave residue (stain) when gently wiped across a surface. For evaluation 3-4 grams of material is shaped into a disk (resembling a bottle cap). Using a flat washer (or similar) apply gentle pressure and streak sample in a straight line 15 inches across a smooth surface. Gently sweep away residue not adhered to surface.

Smear Index




Material leaves trace amounts of residue and most remaining material is easily swept away



Material smears across a third of 15” length leaving behind moderate streaks (<5”)



Material smears across a two-thirds of 15” length leaving behind considerable streaks (5-10”)



Material smears across the entire 15” length leaving large steaks


Stain:    Residue that leaves a stain or requires cleaning / scrubbing to remove. For evaluation use a paper towel and cleaner to wipe clear any smears left behind in evaluating the smear index.  

Stain Index




Residue is easily removed with gentle wipe of paper towel requiring minimal cleaner



Residue is removed with several wipes of paper towel and requires cleaner to remove residue



Removal of residue requires multiple wipes with moderate force and requires several applications of cleaner to remove residue



 Removal of residue requires multiple forceful wipes and requires multiple applications of cleaner to remove residue. Signs of staining remain after cleaning.


Dustiness:      Consisting of or containing dust. Powdery.  The tendency for handling & transfer of material to cause dust clouds resulting in poor air quality and dust cover of adjacent surfaces. For evaluation gently knead sample in open fist to break apart aggregates. Allowing sample to sift through fingers, gently clap hands together to remove remaining residue from hands.





Handling of sample results in no dust



Material is broken into aggregates but creates minimal dust



Material is easily broken into poorly formed aggregates that create dust when agitated



Material crumbles into small fragments and creates significant amounts of dust when handled. 


How well does THIB work?  Taylor suggests a protocol whereby generators of biosolids products test product over a period of several weeks. This establishes both a baseline representation of a specific process train but also the variability that occurs across time periods.  Taylor is not ready to put out in this TOPICs the results of his Spring 2021 trial, but upcoming WEFTEC and local conferences will be venues for presenting the scoring results for a variety of blended soil products made with thermally hydrolyzed and mesophilically digested biosolids. His finding will show that post dewatered processing using a combination of agitation and passive drying can substantially improve product quality and marketability of biosolids as a consumer-ready product. He remains optimistic that methods developed while working on THIB will aid many utilities in developing a marketable product, returning revenue to the utility and promoting beneficial reuse.  We are finally Getting a Handle on Biosolids Quality!    



Biosolids News 

Addressing the Impacts of PFAS in Biosolids
WWD (9/10/21) - This article gives a general look at PFAS and the planning and management WWRFs are taking to meet regulations. Many WWRFs in the U.S. are proactively evaluating solutions to mitigate PFAS. Source reduction is the most cost effective and efficient solution.

Analysis of PFAS in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS: U.S. Environmental Protection Agency Issues Draft Method 1633
US EPA (9/10/21) - The United States Environmental Protection Agency (“EPA”) has issued Draft Method 1633 (“Draft Method”) titled: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS. This laboratory method is said to identify 40 PFAS compounds in eight media.

Overnight Fire Shutters Ecoremedy Plant
Morrisville, PA (8/23/21) - The EcoRemedy facility in Morrisville, PA recently had a fire breakout in their storage area. The fire started late in the night and no one was injured.

How Technology Is Changing What Happens After You Flush
Washington, DC (7/26/21) - This article highlights the CAMBI technology used to create DC Water’s Bloom product.

Fluvanna County Biosolids Permit Community Meeting
Fork Union, VA (7/25/21) - A community meeting is scheduled for the DEQ to discuss and answer questions about the proposed permit for the land application of biosolids, such as site-specific information, the standard content of permits that regulate land application, and how to provide comments on the permit.

Cleantech Company 374Water Touts PFAS-Eliminating Technology That ‘Makes Toxic Sludge Turn To Water’
Kokomo, IN (7/26/21) - Merrell Bros company will be making and servicing 374Water’s AirSCWO NIX systems and installations throughout the United States and Canada.

Maryville Compost Available for Pickup Saturday
Maryville, TN (7/27/21) - Maryville's wastewater treatment plant offered free compost to individuals on Saturday, July 31, and will continue to offer the biosolids compost on Wednesdays throughout the summer. 

Forever Chemicals and Our Food, Water Supply
An in-depth look into PFAS, PFOS, and what the state of Michigan plans to do about them. This article mentions a new law Maine Gov. Janet T. Mills signed into law recently, clarifying that legal cases alleging damage or injury from PFAS can be filed up to six years after the harm was or could reasonably have been discovered.

Tuas Integrated Waste Facility Begins Next Stage
Tuas, Singapore (7/31/21) - Singapore is developing an integrated water and solid waste treatment facility, in Tuas. The 400-tonnes-a-day food waste treatment facility and an 800-tonnes-a-day sludge incineration facility are the first phase of a larger project to develop the Tuas Nexus Integrated Waste Management Facility. The next phase of the project will be started after 2025.

Anglian Spreads the Word on Its Yield-Boosting AD Technology
Utility Weekly (8/3/21) - In this interview, Steve Riches, Anglian’s lead for heating, pasteurization, and hydrolysis - HpH technology explains that the system is now ripe for wider adoption.

Solar Power To Solve Sticky Sewage Sludge Problem
CleanTechnica (8/14/21) - The Energy Department recently awarded a $3 million grant to Solar Dynamics as part of a new $45 million round of funding for solar energy manufacturing and grid technologies that “seamlessly integrate clean energy sources onto the grid.” Solar Dynamics will add $21 million to its share of the pot, for a project under the title, “Solar-Thermal Biosolids-to-Fertilizer Demonstration.”



Composting is an enduring process for transforming biosolids into a Class A EQ product. Compost facilities in the mid-Atlantic region span a full array of sizes, technologies, and ownership models.  The region has facilities located both at small water reclamation plants and at large treatment plants. It has windrow systems, enclosed static pile, and in-vessel agitated beds. Composting is done with various amendments -- purchased wood chips, yard debris, and organic matter recovered from solid waste. The region has various ownerships -- municipally-owned and operated composting, municipally-owned and contract-operated, and privately-owned merchant facilities. The common element to all of this variety is a product that is has a firm place in the landscape market for use in residential and commercial landscaping, as a component in soil blending, and as a specialty amendment for agriculture.  Biosolids compost is a well-tested and well-accepted soil product. What is more, at least two more biosolids composting facilities are in permitting within the region.  Below are several of the branded biosolids compost products made by MABA members

McGill SoilBuilder Premium Compost

McGillFor more than 30 years, McGill Environmental Systems has designed, built, and operated state-of-the-art indoor facilities for industrial-scale production of McGill SoilBuilder Premium Compost.   It manufactures this premium compost product through the processing and recycling of non-hazardous, biodegradable by-products and residuals from municipal, industrial, and agribusiness sources. The McGill Regional Composting Facility at Waverly (McGill-Waverly) opened in 2008.  It is in Sussex County, Virginia, near the town of Waverly.  Its primary service area includes the coastal mid-Atlantic region.  This encompasses the District of Columbia south through Richmond-Tidewater to northeastern North Carolina. McGill-Waverly accepts all types of biodegradable materials including food waste and compostable plastics.  It is designed to receive and process source-separated wastes transported in roll-off containers, tractor-trailer rigs, and other commercial vehicles that can safely tip into the receiving bunker. Located on a former timber tract, the operation processes in both banked and encapsulated bays with aerated curing.  Aerated curing eliminates the need for windrow turners at this facility.
For more information, contact Sean Fallon, Business Development Manager, [email protected], 919-406-4270. The Waverly facility is located at 5056 Beef Steak Rd, Waverly, VA 23890.

WeCare Compost

WeCareWeCare Denali, a division of Denali Water Technologies, operates 24 composting facilities around the United States, two of which are county-owned biosolids composting plants.  The Burlington Biosolids Composting Facility is a 300 ton per day capacity composting facility in Columbus, NJ, owned by Burlington County, but operated by WeCare Denali, serving about 20 agencies in the county and beyond.  It is the largest biosolids facility in New Jersey under contract operations. The Rockland Green Co-Composting Facility, owned by the Rockland County Solid Waste Authority, recycles biosolids from wastewater plants in Rockland County, NY. At both plants, biosolids are mixed with clean wood waste and then composted in in-vessel agitated bed composting systems. The finished product is used on golf courses, flower gardens, and landscaping projects, and are also ingredients in topsoil This plant is adjacent to the Authority's Materials Recovery Facility and Transfer Station in Hillburn, NY. WeCare Denali markets a suite of WeCare Compost products under its WeCare Compost, Mulch, & Soil line.

For more information, contact national sales manager, Ryan J. Cerrato, [email protected], 315-575-4595. The Burlington facility address is 800 Coc-co Lane, PO Box 318, Columbus, NJ 08022. The Rockland facility is 1988420 Torne Valley Road, Hillburn, NY 10931.

 ORGRO High Organic Compost

baltimoreORGRO is a product of the Baltimore City Compost Facility, a facility owned and operated by Veolia, under contract with the city of Baltimore Department of Public Works. This facility, which was first built in 1984, processes a 45 dry ton per day portion of the anaerobically digested biosolids from the Back River Wastewater Treatment Plant, the balance made into a thermally dried product. The compost plant produces about 35,000 cubic yards of compost in through in vessel composting and extended curing. This facility is one of the original national examples of a public-private partnership, and one of the original programs for commercial marketing of biosolids to commercial landscapers.
For more information, contact Tom Fantom, project manager, [email protected], 410-354-1636. The facility address is 5800 Quarantine Road, Baltimore, MD, 21266.

Landscaper’s Advantage

A&MLandscaper’s Advantage is the product of the A&M Compost Facility, a large enclosed static pile composting plant owned and operated in Manheim, Pennsylvania by the J.P. Mascaro company.  It is a merchant plant, accepting biosolids from a wide reach of plants in the mid-Atlantic. The facility is nearly 15 acres under roof.  Its website offers a “virtual tour” slide deck describing the components of its operation and its environmental controls, which includes under one cover both aerated composting and biofiltration.  A&M is managed by a registered professional engineer, Ryan Inch, PE, and a compost specialist, Mark Hubbard.  

For more information, contact Matt Mascaro, [email protected],  267-228-5288. The facility is located at 2022 Mountain Rd, Manheim, PA 17545.

 earthlife Compost

hawkridgeThe Hawk Ridge Composting Facility, New England’s largest compost facility, is owned and operated by Casella Organics, a MABA Board member  This facility uses an in-vessel tunnel system (the Gicom Tunnel) to compost a blend of biosolids with woodchips and sawdust, producing a screened compost with the tradename earthlIfe.  Recently, Hawk Ridge reached the distinction of delivering its one-millionth cubic yard of compost. Its wholesale customers include golf courses, nurseries, garden centers, and athletic facilities. 
For more information, contact John Leslie, [email protected], 207-461-1000. The facility is located at 3 Reynolds Road, Unity, ME 04988. 

MABA Event Presentations

2021 Webinar - March 2021 on Enhanced Digestion

2021 Webinar - May 18 2021 on Solids Treatment

2020 November Phosphorus 101 Webinar

2020 Summer Webinar Series

2019 Summer Symposium

2018 Annual Meeting & Symposium

2018 Summer Symposium

2017 Annual Meeting & Symposium

2017 Summer Symposium

2017 NJWEA Workshop

2016 Annual Meeting & Symposium

2016 Summer Symposium

2016 NJWEA Workshop