DC Water is marketing its EPA-certified “Exceptional Quality” Class A Biosolids as a retail soil additive called Bloom. Biosolids are merely the sludge that comes out of a wastewater treatment plant. DC Water is not the first wastewater utility or DC area utility to turn its wastewater biosolids into a soil additive for home gardeners and crops for human consumption. AlexRenew sells their Class A Exceptional Quality bio-solids to farmers in Virginia; and some of the Class A Biosolids are combined with wood fines, creating a soil amendment product that they are calling “George’s Old Town Blend.”
At DC Water’s Blue Plains and other
sewer treatment plants primary treatment uses screens to remove large solids
from wastewater which then sits in settling tanks, which are designed to hold
the wastewater for several hours. During that time, most of the heavier solids
fall to the bottom of the tank, where they become a thick slurry known as
primary sludge.
The sludge is separated from the wastewater during the primary treatment is
further screened and gravity is allowed to thicken the sludge in a tank. Then
the sludge is mixed with the solids collected from the secondary and
denitrification units. The combined solids are pumped to tanks where they are
heated to destroy pathogens and further reduce the volume of solids. With
treatment sludge is transformed (at least in name) to Biosolids.
In 2015 DC Water unveiled the newly completed and operational sludge
treatment system. Blue Plaines now has Cambi thermal hydrolysis
trains, four digesters, dewatering equipment and a combined heat and power
plant that cost $470 million. The new digestor system uses thermal hydrolysis
(heating to over 160 degrees under high pressure) followed by anaerobic
digestors. This takes care of the pathogens.
Bloom is an “EPA approved Exceptional Quality Class A
biosolids.” This means that Bloom has been tested for a limited list of
contaminants. Class A biosolids can provide essential plant
nutrients, including slow-release nitrogen, and organic matter, by slowly add
nutrients to the soil by naturally breaking down and decomposing into a
plant-available form which is helpful in building healthy soil. However, we do
not actually know what other contaminants are in the biosolids and there are other ways to build healthy soil.
The real need addressed is disposing of the biosolids. DC Water encourages the
use of Bloom for water holding capacity, improving and establishing lawns,
remediating poor soils, planting trees and shrubs, and establishing flower and
vegetable gardens. I don’t think this is a good idea.
U.S. EPA regulations limit metals and pathogens in biosolids
intended for land applications, but no organic contaminants are currently
regulated under 40 CFR
Part 503 Rule created in 1989 and still in effect today. Only metals and
pathogens are tested for. It categorizes Biosolids as Class A or B, depending
on the level of fecal coliform and salmonella bacteria in the material and
restricts the use based on classification. There turns out to be many more
contaminants in sewage sludge. Over the years controversy associated with
potential impacts of Biosolids and the land disposal or reuse of Class B and
even Class A Biosolids have grown.
The presence of other contaminants in the Biosolids has not
been tracked, but has become an emerging area of concern. Previously, research
at the University of Virginia found that organic chemicals persist in Biosolids
and can be introduced into the food chain. Land application of biosolids is a
widespread practice across the US and remains an approved method by the US EPA.
This practice is now being questioned.
In April 2024, the EPA announced the final national primary
drinking water standards for six poly- and perfluoroalkyl substances (PFAS).
Public water systems have five years (by 2029) to implement solutions that
reduce these PFAS if monitoring shows that drinking water levels exceed the
maximum contaminant levels (MCLs). The limit for PFOA and PFOS at or near the
MCL of 4.0 parts per trillion (ppt) individually. For PFNA, PFHxS, and HFPO-DA
(GenX Chemicals), EPA is setting MCLs of 10 parts per trillion combined. Per-
and Polyfluoroalkyl Substances (PFAS) do not occur in nature, they are an
entirely synthetic substance and are highly stable which is how they got their
nickname “forever chemicals.”
DC Water reports that they have tested Bloom for various
PFAS chemicals. They have found concentrations of PFOS and PFOA within ranges
of 4.60 to 16.1 parts per billion (ppb) and 1.7 to 3.7 ppb respectively
– a thousand of times higher than the primary drinking water standard, but
lower than than in food packaging materials; and cosmetics; and lower than the
levels measured in dust. Bloom’s total combined PFAS levels average 130 ppb. Though
very water soluble, PFAS are resistant to degradation and simply flow through
the wastewater treatment plant. PFAS remains in the biosolids and effluent.
Though PFOS and PFOA have been eliminated from production,
exposure to them is still occurring. Almost all of the PFOS and PFOA ever
manufactured is out there still circulating in the hydrologic cycle. According to the National Institute of Environmental Health
Sciences (part of the NIH): “People are most likely exposed to these chemicals
by consuming PFAS-contaminated water or food, using products made with PFAS, or
breathing air containing PFAS. Because PFAS break down slowly, if at all,
people and animals are repeatedly exposed to them, and blood levels of some
PFAS can build up over time.”
One report by the Centers for Disease Control and Prevention, using data from the
National Health and Nutrition Examination Survey (NHANES), found PFAS in the
blood of 97% of Americans. Even when/ or if the source of exposure is
removed, measurable levels of PFASs may be detected in humans due to the
relatively long half-life of these chemicals. The estimated half-life for PFOS,
PFOA, and PFHxS in humans ranges from 3.8 to 8.5 years.
Practically everyone has been exposed to PFAS and DC Water
seems to want to assure that the PFAS out in the environment continues to
spread. There are thousands of PFAS chemicals, and they are found in
many different consumer, commercial, and industrial products. PFOS
and PFOA were used in Scotch Guard, the manufacture of Teflon and traditional
Aqueous Film-Forming Foam (AFFF) - the Class B firefighting foam used to fight
aviation and other chemical.
After AFFF is deployed in an emergency or training exercise,
it can seep into the ground, or flow to the storm drain system and contaminate
soil, surface water and groundwater. Then there was the wastewater from the
manufacture of flame retardants, Teflon, Gortex, Scotch guard and other coating
that was buried, ponded or simply released into streams. PFAS began to spread
in the environment.
Then onto consumer products. Coatings were sprayed onto cans
and food packaging. Wash water from light manufacturing or processing.
Treatments for fabrics. The companies that applied the stain resistant and
flame resistant treatments to carpeting, upholstery, clothing sent their wastewater
to the wastewater treatment plants which cannot remove PFAS. PFAS containing
packaging picked up traces of PFAS and it was passed onto people that way, too.
The PFAS ended up in the effluent and the biosolids. The
reach and spread of PFAS was increased because effluent from wastewater
treatment is released to rivers and used as source water for drinking water.
Out it went to rivers and streams ultimately to the oceans. Fish and seafood
were exposed to PFAS through the wastewater effluent as are we. The wastewater
effluent is often upstream of drinking water plant intakes or intentionally
reused. The Occoquan receives up to 40 million gallons a day of treated wastewater
from UOSA.
Wastewater treatment plants generate biosolids which also are
contaminated with PFAS. Biosolids were land applied in agriculture (cheap "natural" fertilizer in Maine) and buried in landfills.
Animals grazed on the land, food grown on the land picked up some of the PFAS
and passed traces into food. People passed it onto other wastewater treatment
plants and the circle widened.
When our analytical methods were less precise and PFAS had
less time to permeate our environments, we used to think that only people
living near the industrial manufactures of PFAS, their industrial waste
disposal sites or airports were exposed. The ability to measure parts per
trillion disabused us of that belief and allowed us to understand we have helped
spread PFAS almost everywhere .



















