Application of Sewage Biosolids on Land
The 2004 National Water
Quality Inventory by the US EPA reported that 44 % of surveyed rivers and
streams were impaired by pathogens and organic enrichment, and the top source
of these impairments was from runoff from agriculture activities. In addition,
30 % of surveyed bays and estuaries were considered impaired by pathogens and
organic enrichment, with municipal discharges/sewage listed among the top three
sources of the impairment (US EPA, National Water Quality Inventory Report to
Congress, 2004 Reporting Cycle, Jan. 2009). Also in 2004 approximately 60 % of
total “biosolids” produced in the US were applied to land, (NEBRA, A National
Biosolids Regulation, Quality, End use and Disposal Survey—Preliminary Report,
April 14, 2007). Since 2004 more stringent effluent discharge requirements and
sewage treatment plant upgrades have resulted in significant increases of
sludge production and hence the need to dispose of it in an acceptable manner.
Public doubts regarding the efficacy and safety of land application have been
supported by scientific research that indicates commercial chemicals,
pharmaceuticals, personal care products, engineered nanoparticles and
innumerable contaminants of emerging concern (COEC) are having a greater impact
on the environment and public health than previously assumed (Abstracts of
Presentations, “Environmental Protection in a Multi-Stressed World: Challenges
for Science, Industry and Regulators,” 25th Annual Meeting of SETAC,
2015, Barcelona). Further studies and alternative methods of extracting and
processing the components of sewage and disposing of the sludge are required.
There is potential for reducing the life cycle costs of sewage treatment
plants, recovering energy and destroying or immobilizing harmful components
instead of being applied to land, (Biosolids Management Strategies: An
Evaluation Of Energy Production As An Alternative To Land Application,
Environmental Science and Pollution Research International, Jul 2013).
Composition of sludge/biosolids.
Sewage sludge, when
treated in an anaerobic digester or further treated with heat or alkali is now
called biosolids in order to make it sound more acceptable for “beneficial”
uses such as spreading on farmland. The sludge/biosolids contains nutrients
useable for plant growth, however they also contain in addition to human and
animal wastes, 30,000 or more different toxic chemicals from pharmaceuticals,
hospital, household and industrial waste, bacterial, viral and other parasitic
biological pathogens, multi-drug resistant bacterial/Superbugs and prions,
heavy metals, micro-plastics and micro-fibres. One class of these thousands of
chemicals in sludge/biosolids is called PPCPs or Pharmaceuticals and Personal
Care Products and these compounds are taken up by plants in hundreds of
micrograms per kg of plant tissue and nothing is known about the effect of this
on the plants and on the animals that consume them including humans. The uptake
and metabolism of these thousands of different compounds varies greatly with
their composition. (M. Bartrons, J. Peñuelas, TRPLSC 1514, 12, 2016, p.10).
Health Effects
Damage to DNA from
environmental chemicals is likely a major cause of cancer, birth defects, and
this uptake may contribute to heart disease and other health effects. Genetic
defects get carried over to future generations; exposure to mutagens is from
natural sources but increasingly from synthetic chemicals such as industrial
chemicals, pesticides, hair dyes, cosmetics and pharmaceuticals, (Bruce N.
Ames, Dept. of Biochemistry, UC Berkley).
When substances have a
similar mode of action, their concentrations can be added together to predict
their combined effect. This includes concentrations below levels of concern and
the toxicity effect is larger than the sum of the components. Although
antagonistic and synergistic effects occur, the additive effect of toxicity is
generally what occurs (Environmental Toxicology and Chemistry, Dick de Zwart
and Leo Posthuma, Vol 24, Issue 10, Pg 2397-2713 – Modeling of single and
multiple chemicals in the environment).
Environmental oestrogens
in wastewater treatment effluent are well established as the primary cause of
reproductive disruption in wild fish populations but their possible role in
wider effects of effluents is under study. Filby et al, revealed a clear link
between oestrogen in effluent and diverse, adverse and sex-related health
impacts on resident fish species, (Environmental Health Perspectives, Vol. 115,
No. 12, Health impacts of oestrogen in the environment, considering complex
mixture effects, December 2007, Amy L. Filby, Teresa Neupath, et al).
What happens to the contaminants in the
sludge/biosolids?
If governments continue
to allow the application of 30,000+ chemicals and PPCPs and many countless
biological pathogens on the land, they should prove beyond any reasonable doubt
that these contaminants are either removed from the sludge/biosolids before
land application or will be destroyed when applied on the land. However, the
proof is simply not there. This is a herculean task,
it will be impossible to measure the concentration and the rate of removal or
the decomposition of 30,000+ chemicals applied on the land. The technology does
not exist to measure these thousands and thousands of chemicals and the cost of
doing so even if it were possible would be prohibitive. Even though endogenous
soil bacteria can probably degrade a small number of chemicals in the sludge,
the metabolic pathways to degrade and destroy 30,000+ synthetic chemicals that
did not exist in the past, do not exist. A certain amount of these thousands of
chemicals will be water soluble and with other small particles including
microplastics they will get washed away with the rains and will end up in the
streams, rivers and the ocean or will contaminate aquifers. Effluent discharges
have been expressed as the mode for contamination that is reputed to play a
role in the formation of “dead” zones or oxygen depleted “hypoxic” zones in
lakes and the near shore oceans around the world (Scientific American, 2008;
National Ocean Service, US Dept. of Commerce, 2010). The oceans are exploding
with dead zones (Business Insider, June 26, 2013), and the zones appear to be
increasing in size over time.
Clearly, there are toxic
chemicals in sewage sludge.
We also do not know
anything about what other toxins can form from a 30,000+
chemical soup when sludge is being treated/turned into biosolids. Furthermore,
nothing is known about what synergistic effects this chemical cocktail will
exhibit when applied on the land. Another unknown is what effect the many
antibiotics present in the sludge/biosolids will play on the plant microbiota
or on the microbiota of the animals that live on the land where the
sludge/biosolids get applied. Both endogenous
bacteria as well as mycorrhizal fungi play a crucial role in the growth of
plants and trees and altering this microbiome with antibiotics present in the
sludge/biosolids can easily negate its nutritional benefits.
Biological Pathogens
Sewage sludge/biosolids
also contains largely an unknown
number of bacterial and viral pathogenic organisms, protozoan and other
parasites and even prions. What is often never discussed in the pro-sludge and
biosolids literature is the fact that ALL sewage treatment plants in the world,
including all secondary and tertiary treatment plants breed Superbugs or
multi-drug resistant bacteria, (Y. Luo et al, Environmental Sci. Technol. Lett.
2014, 1, 26-30; A. McGlashen, Sci.Am. 2017, 01/18.) The reason is simply the
fact that antibiotics end up in sewage and during the treatment process with
bacteria, the bacteria that acquire antibiotic resistance will get selected in
the presence of antibiotics in the sewage. However,
the level of treatment (secondary or tertiary) will affect the
degree of ocean protection from the contaminants in the sludge. The sludge is
simply settled out in secondary treatment and the effluent which is too dirty
to be reused typically gets pumped to a receiving environment, such as, a
river, lake or into the ocean. However, in tertiary treatment, the sludge gets
filtered from the water with 0.04 micron membranes and this step will remove
not only the bacteria, but also the source of the bacterial multi-drug
resistance or Superbugs, the plasmids. Plasmids are small circles of DNA which
contain the genes for the drug resistance and can confer the resistance not
only to same species bacteria, but also to unrelated bacteria such as the
endogenous soil bacteria. These small circles of DNA called plasmids can
survive outside of the bacteria either in water or can even survive for
hundreds or possibly even thousands of years in a completely dry state. Plasmid
DNA has even survived on the surface of a rocket shot into space and the heat
of re-entry into atmosphere, (D.F. Maron, Sci. Am. Nov. 26, 2014). So it is
totally unrealistic to hope that Superbug DNA will somehow magically disappear
if we let the sludge sit on the land for a few months. The addition of 5-10 or
larger micron size disc filters suggested to improve the quality of the
effluent instead of the 0.04 micron membrane filters used in real tertiary
sewage systems will do nothing for the environmental protection because it will
NOT filter out plasmids or anything else smaller than the pore size of such
filters.
Fraser Health has
repeatedly found cases of the deadly CRE (Carbapenem Resistant Enterococci) in
BC Hospitals, however CBC has reported (CBC News, Jan. 30, 2017) that many
other hospitals in other provinces are silent on these outbreaks and that there
were apparently 160 cases of CRE outbreaks between 2010 and 2012 (Public Health
Agency of Canada). These and other Superbugs make their way into the sewage
treatment Plants from the hospitals, homes and industrial facilities and so it
makes sense that we should not spread them or plasmids containing the genes for
this resistance on the land where they can further contaminate and multiply
their resistance genes.
Micro-plastic and micro-fibres
Sewage
contains micro-plastics from a variety of cosmetic products and micro-fibres
that are released into waste water from laundry and industrial processes. These
microscopic plastics will remain on the land or be washed from the land into
streams, rivers and into lakes and the ocean where they will do their
environmental damage. A recent study by the International Maritime
Organization, the UN Organization responsible for preventing marine pollution,
and carried in
Science and Technology
Journal and also reported by CBC, posted to their web site on January 17, 2017
indicates that microplastics are now found in supermarket fish and shellfish.
They have infiltrated every level of the food chain in both the marine and
fresh water habitats and now we are seeing them come back to us on our dinner
plates, (Chelsea Rochman, University of Toronto, 2017). These materials not
only enter the gut but also their tissue says Peter Wells, senior research
fellow at International Ocean Institute, Dalhousie University. He goes on to
say, it’s not only the micro-plastics but the myriad of chemicals that come
with them, chemicals such as PCB’s, pesticides, flame retardants and hormone
disrupting compounds of many kinds. Although micro-plastics come from many
sources and are known to carry chemicals of emerging concern, it behooves us to
eliminate sources where possible, including the land application of sewage
biosolids.
Micro-plastics are found
at an alarming level in Canadian Lakes, Science and Technology Journal, and
also reported by CBC, January 2017. They are a concern in lakes worldwide and they
are often found at alarming levels says Anthony Ricciardi, professor at McGill
School of the Environment. Their source is often municipal coming from the
washing of clothes but also from industrial sources and are found at 43,000
plastic particles per square kilometer which jumps to 466,000 near cities
around the Great Lakes.
No one wants to eat fish
that contains non biodegradable plastics including the many toxins absorbed to
these plastics, so it makes sense not to spread them onto land in sludge/biosolids
in order to stop further contamination of both the land and the waters.
Micro-plastics are
synthetic polymers and cannot be broken down by microorganism no matter how
long they will sit on the land or in the ocean. They will survive for many
hundreds of years without any noticeable degradation and are eaten by fish,
plankton and other marine and fresh water animals, (M.L. Taylor et al,
Scientific Reports 6, Article number: 33997 (2016). As
noted, the actual toxicity of the micro-plastics themselves is also increased
by absorption of toxic chemicals onto their surface. These polymers can't be
broken down/metabolized by any creature that ingests them and so if they are
loaded by absorbed toxins, they become even more lethal, (M.A.Browne et al. Current Biology, 2013; 23 (23): 2388).
The indefinite Problem
Tens of thousands of
these components will contaminate the land for decades and perhaps hundreds if
not thousands of years once they are applied on the land and there simply is
nothing one can do to decontaminate such land. Furthermore, the tests that
would determine the extend to which these toxins will be taken up by the plants
or animals we consume simply do not exist, with 30,000 different synthetic,
man-made chemicals it is unrealistic and impossible to measure the fate of
these chemicals once they are applied on the land. The same goes for the vast
majority of biological pathogens like Superbugs that will be spread on the land
with the sludge. Once micro plastics from sludge are applied on
the land, they will contaminate the land for hundreds of years or waterways if
they get washed away by rain. Once it’s applied on the land, it will either
stay there or will end up in the rivers, lakes or the ocean - the genie cannot
be put back into the bottle once it gets out so the best solution is not to
apply this toxic mixture on the land in the first place.
What do we do with it these sludge toxins? How do we
safely dispose of this sludge/biosolids?
The wastewater industry
currently has a preference to treat sewage sludge and turn it into a material
called “biosolids,” a marketing term developed to make it more appealing to
farmers to encourage spreading it on the land. It represents a relatively inexpensive
way to dispose of the sewage biosolids. Sewage sludge treated in an anaerobic
digester converts approximately half of its carbon into biomethane, however,
the problem remains what to do with the remaining 50% of the solid residuals.
There are risks associated with anaerobic digesters, they are known to explode,
thus the reason they are not installed in built-up residential areas.
Thermal conversion is
also an option for sewage biosolids disposal, with a remaining issue on how to
safely dispose of the ash should it contain potential heavy metal issues. There
are two types of thermal conversion, firstly, incineration which has been
rejected in many jurisdictions because of the large volumes of air pollutants
released during the process; and secondly, gasification which reforms (or
manufactures) the sewage biosolids into synthesis gas (syngas) and does not
have the massive air pollution issues of an incinerator. In advanced gasifier
systems there are no direct air emissions at all. Small gasification systems,
suitable for the disposal of sewage biosolids, have only recently been
developed having started in Europe in the mid 1990’s. These first generation
systems have given way to further development into second and third generation
systems which are much more reliable, stable and efficient than the earlier
systems. The Advanced gasifiers can handle either dewatered raw sewage sludge
or dewatered treated biosolids from a digester, the only difference being
higher syngas production from the raw sludge. Due to their size compared to
anaerobic digesters and municipal incinerators they are much more cost
effective and require far lower operating costs as well.
Lessons learned
K. Noguera-Oviedo and D.
S. Aga (J. of Hazardous Materials, 316 (2016) 242-251) reported on the lessons
learned from more than two decades of research on emerging contaminants in the
environment. Just like the exponential growth of research papers published on
the topic of Emerging Contaminants (ECs) in the period of 1995-2015, detection techniques
have been vastly improved and the amount of data has also grown exponentially.
Noguera-Oviedo and Aga identified five (5) lessons learned from research of the
past 20 years and reported that these lesson matter now more than ever before.
Lesson
1: Emerging Contaminants have emerged worldwide in Waste Water Treatment Plants
effluents and in surface water, drinking water and groundwater. The
precautionary principle should be used in dealing with management options for
this material.
Lesson
2: Treatment does not mean complete removal and application of the sludge on
the land only exacerbates this problem.
Lesson
3: Metabolites and transformational products matter, meaning that during the
treatment or after it, the mixing of thousands of these chemicals often forms
new compounds that are more dangerous than those that they originated from.
That’s the nature of chemical processes and unless we actually destroy the mix,
new toxins will continue to emerge from the old ones, whether it is on the land
or in streams, rivers, lakes or the ocean.
Lesson
4: Unconventional testing of the effects of toxicity are needed, because of the
complex mixture of chemicals in the effluents and in the sludge. The simple
testing done by the pharmaceutical industry while developing new drugs does not
apply in this new world of toxic waste chemicals.
Lesson
5: Even the most advanced tools can miss the target. The exponential growth of
scientific literature in detecting these compounds will not negate the need to
prevent even further contamination of the environment by persistent ECs.
In conclusion, it seems
obvious that application of sewage sludge/biosolids on the land is not the
answer to dispose of these toxins and pathogens. Disposal of the sludge mixed
with municipal solids waste or with wood chips in a gasifier is the only safe
way to go because it completely destroys the toxic chemicals and pathogens. Not
putting this toxic soup on the land is the only way of protecting our
environment and that’s the primary reason for treating our sewage in the first
place.
Experts from Cornell Waste Management Institute
Dr. Caroline Snyder’s,
emertitus professor, Rochester Insttitute of Technology, written testimony to
the PA House Demoncratic Policy Committee, Public Hearings on sewage sludge has
been summarized as follows:
“Experts, including soil
scientists at the internationally renowned Cornell Waste Management Institute,
who have studied biosolids - since the 1970s - with hundreds of peer reviewed
papers to their credit, oppose using biosolids and biosolids products on the
land where we grow our food and forage. Additional research teams led by Hale,
Lewis, Wing, as well as the National Academy of Sciences, and others have
reported and documented serious health, environmental, and agricultural harm
linked to land application. The damage from this pollutant-rich waste mixture
is not just "potential;" it has already happened. It is a gross
travesty to call this material "eco-friendly" or to claim that the
process "sanitizes" the solids. In fact, standard methods to further
process sludge to a so-called Class A product actually encourages the growth
and proliferation of endotoxins, and superbugs, as the more vulnerable
indicator pathogens are deactivated, which explains why a number of sludge-exposed
neighbors suffer from MERSA infections and life threatening respiratory
symptoms. With mounting scientific evidence that current regulations and
policies do not protect human health, agriculture, or the environment, why are
US and Canadian agencies still promoting this harmful practice? For the answer
see http://www.sludgefacts.org/testimony_to_pa.pdf “
Land application is not
"recycling"; it is simply transferring a complex mixture of toxic
chemicals and pathogens from our large industrialized urban centers to arable
farms; nor is the practice "strictly regulated." Current biosolids
management is highly energy intensive using fossil fuel for processing and
transportation, thus - actually adding greenhouse gas emissions (on top of all
the pollution produced by hauling these materials all over). Finally, it is
ludicrous to claim that using the nation's arable soils as a repository of
persistent toxic chemicals, many of which bioaccumulate in the food chain,
"enhances soil health".”
Thomas
Maler, Ph.D. (chemistry, biochemistry, molecular biology) Victoria, BC
