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How Can We Be Sure That Our Composts Are Safe?

When we use compost on our vegetables, we rely on them to be pathogen free. We can’t take the risk of transferring pathogens such as E.coli and fecal coliform from our compost onto our vegetables.

Many organic vegetable and fruit growers rely on manure and compost as a supply of nutrients for their crops.

There are rules with using manure, including a period of time required between application of the manure and harvesting the crop, particularly for vegetables. Manure contains potential pathogens, and it is considered that these pathogens will die within a certain time.

For composts, achieving high temperatures is considered enough to kill potential pathogens. However, some composts, even though they have met the temperatures required for pathogen kill, should be treated like raw manures. This is because when they cool, or when they become wetter, the potential pathogens regrow.

Immature composts are more likely to be at risk for potential regrowth of pathogens.

We have been working on a protocol or guidelines to help ensure that our composts are safe.

The City of Whitehorse produces an OMRI Listed compost from their residential organics program. They wanted guidelines on how to ensure the safety of the compost that they sell. We did extensive testing and found that there was no potential regrowth of pathogens with their marketed product. Based on this, we propose the following protocol to ensure that our composts are safe:

  1. Cure the compost to achieve a maturity rating of < 2 g CO2-C per gram of organic matter
  2. Perform a potential regrowth test that involves taking some of the compost, wetting it to 50-60% moisture and leaving it in a container for 24-48 hours, before taking a sample
  3. Have the sample analyzed for E.coli as well as for fecal coliform as it is a better indicator of potential pathogens.

We are currently testing this protocol ourselves, and what we found surprised us! E. coli does regrow in marketed finished compost here in British Columbia!

I’ve heard the comment before – my compost does not contain biosolids or animal manure, therefore pathogens are not a concern. Sadly, information in the literature years ago already, and our experience today indicates that the purchase of residential organic waste compost may be just as likely to result in regrowth of high levels of E. coli and fecal coliform.

We need to work together, to protect the integrity of the composting industry, to protect the livelihoods of our organic growers, and the health of all of us!

We’d love to get your feedback on how we may be able to improve the protocol so that we can clearly demonstrate that our compost products are safe!

New Master Compost Course Offered in Abbotsford

We need to clear the air regarding composting. For many of us, composting is positive. Unfortunately, for some of us, the word composting brings up negative or conflicting emotion, in part because of the increasing concerns regarding odour, or perhaps because the increasing amount of plastic bits that we are finding in our soils. For others, composting may not bring up much emotion at all, simply because we do not understand it.

In this new course, we will explore and explain the magic of the compost process, and why composting is so important to the health of our planet, and our future in it. Did you know that when we get the composting process right, we can smell it – in parts per trillion? Did you also know that when we don’t get it right, we can also smell it in parts per trillion? We will explore how our nose is so important in understanding the amazing microbial community that lives in our compost – and our soil.

You will have the opportunity to work with our “magic boxes” that help demonstrate and explain some of how physics, chemistry and microbiology work together in the composting process. You will meet Jerome, our new assistant with particular skill in measuring hydrogen sulphide – and to understand how and why this is important! You will learn how two composts that can look the same – can have such as contrasting effect on plants! We will welcome you to the world of worms, their role in composting and in soil.

Hands-on experiences with the “magic box” and the hydrogen sulphide analyzer help us understand more about the composting process.

This course builds on the Advanced Composting Course that I have taught in Victoria for the last few years. It also builds on the Compost Facility Operator course that I have taught in Abbotsford since 2006 – with more hands on in making and using compost.

This course is for all who are curious about composting and compost use, whether you are a composter, a regulator, a community member, an administrator, media, government staff, or just curious. This course gets us all down in the dirt together, as we explore how important our soil organic matter is, and how it protects us and helps us all to flourish!

We will explore regulation, what it is, what is important, and how we can advocate to make this amazing composting process a socially acceptable endeavor, and how we can ensure that our health and environment remains protected for us and for our children.

The course will be held at the historic Clayburn schoolhouse, a location with a long history of community learning. You will enjoy homemade meals each day, which possibly may include roast beef cooked in the compost pile (or we may just show you how its done). Happy hour is available at the end of the day – we are working towards enjoying it in a hot tub heated by compost!

The course is scheduled for April 4-6, 2018. See for more details.

Reducing Discharge of Pharmaceuticals into the Environment

Although our toilets are the major route of pharmaceuticals entering the environment, we do not encourage a ban on them. At least, not yet. Between 30-90% of pharmaceuticals pass through our bodies and are excreted in urine.

“The consumption phase is considered to be the biggest contributor to the emissions of medicinal products into the environment, notably through excretions and incorrect disposal of unused medicines through sinks and toilets. Between 30 and 90% of the orally administered dose is generally excreted as active substance in the urine of animals and humans” (Mugdal et al. 2013)

We do not support a ban on toilets at this time

“Urban wastewater seems to be the dominant emission pathway for pharmaceuticals globally” (Haiba and Nei, 2017)

Septic systems and wastewater plants are not designed to remove pharmaceuticals, so many of them remain in the liquid effluent and enter our groundwater, our streams, lakes, rivers and oceans (Godfrey et al. 2007, Schaider et al. 2013, Gaw et al. 2014, CBC 2015, Schaider et al. 2017).

“Our loading estimates suggest that effluent from septic systems and centralized wastewater treatment plants contain similar concentrations of CEC (Contaminants of Emerging Concern). Thus, plans to extend sewer systems may not substantially decrease overall CEC loading, but would change the distribution of these inputs, moving them from newly sewered areas to places where treatment plants discharge” Schaider et al. 2013)

We need to keep our aim in focus. Its difficult to improve septic systems to degrade pharmaceuticals. Its possible to upgrade our wastewater plants through membrane bioreactors, oxidation and ultrafiltration, but its costly.

A small amount of the pharmaceuticals end up in the biosolids. Composting the biosolids is currently the best strategy to reduce pharmaceuticals, as it removes 50-90% of these products.

“conclusions are that sewage sludge application to farmland is an insignificant source of pharmaceuticals to the environment compared to sewage works discharge water, and that pharmaceuticals in sewage sludge are mostly retained in the surface soil and biodegraded there.” Magner 2016.

“Dr Magid concludes that the soil bacterial system is highly resilient and that organic contaminants in sewage sludge or other organic material, as applied, do not seem to pose problems.” Magid 2016

“Biological sewage treatment systems, which are designed for BOD (available organic carbon) removal are not optimal for removing pharmaceuticals and household chemical biocides. On the other hand, composting shows to be effective in achieving > 90% reduction for some organic household chemical biocides.” Butkovskyi 2016 EESP 2016 report

In November 2017, a group of 20 health and environment organizations called for an action plan to reduce the discharge of pharmaceuticals into the environment (EPHA 2017). One of the strategies included:

 “Improve municipal wastewater treatment facilities in order to prevent environmental pollution caused by excreted pharmaceuticals.”

In a circular economy, where we are called to be accountable for all of our actions including our discharges, we do need to keep our discharge of pharmaceuticals into the environment in perspective, and collectively do what we can to reduce them. Our health and our future depends on it.


EPHA. 2017.  20 Organizations call for Ambitious EU Action on Pharmaceuticals in the Environment.

Butkovskyi, A. 2016. Status of knowledge on pharmaceuticals in biosolids. EESP

CBC News. 2017. Pharmaceuticals in wastewater target of sewage treatment study.

Gaw, S., K.V. Thomas and TH. Hutchinson. 2014. Sources, impacts and trends of pharmaceuticals in the marine and coastal environment. Phi. Trans. R. Soc. B 369: 20130572.

Godfrey, E., W.W. Woessner and M.J. Benotti. 2007. Pharmaceuticals in on-site sewage effluent and ground water, Western Montana. Ground Water. 45: 263-271.

Haiba, E., and L. Nei. 2017. Sewage sludge composting and pharmaceuticals. European Scientific Journal Special Edition ISSN: 1857 – 7881.

Magid, J. 2016. Natural robustness of soil. In Report ESPP workshop Pharmaceuticals in sewage biosolids. Malmo, Nov 27, 2016.

Magner, J. 2016. Fate of pharmaceuticals. In Report ESPP workshop Pharmaceuticals in sewage biosolids. Malmo, Nov 27, 2016.

Mudgal, S., A. De Toni, S. Lockwood, L. Sales, T. Backhaus and B.H.Sorensen. 2013. Study on the environmental risks of medicinal products. Final Report. Executive Agency for Health and Consumers. December 2013. Bio Intelligence Service.

Schaider, L., K. Rodgers and R. Rudel. 2013. Contaminants of emerging concern and septic systems: A synthesis of scientific literature and application to groundwater quality on Cape Cod. Silent Spring Institute. Newton MA.

Schaider, L.A., K.M. Rodgers and R.A. Rudel. 2017. Review of organic wastewater compound concentrations and removal in onsite wastewater treatment systems. Environmental Science and Technology. 51: 7304-7317 DOI 10.1021/acs.est.6b04778.

Every Community Produces Biosolids – How Do We Manage Them Sustainably?

We all produce biosolids – how do we work together to manage them sustainably? In 2008, when we volunteered with a housing project in the Philippines, the first priority was to get the sewage to the river as fast as possible, as there was no option for a septic system due to the high water table. It was not a sustainable solution, but the immediate health of the residents was the first priority. Many in our world have been and are dumping our wastewater and sewage in our waterways for years, even today. Unfortunately, it does have an impact in our oceans, on the sea life, including the fish that we eat. We are finding that we are increasingly accountable for our waste management, we can no longer make it  “disappear”.

As we work to reduce the impact of our wastewater systems on streams, lakes, rives and oceans, we are producing more biosolids. There are two reasons for this (Yoshida et al 2014):

  1. More communities and persons served by centralized wastewater facilities, and
  2. Enforcement of stricter wastewater regulations.

Given the increased amount of biosolids being produced, how do we manage these biosolids in a socially and environmentally acceptable manner?

Reuse of biosolids into agriculture has been increasing worldwide, with substantial research showing the benefits of recycling the nutrients and organic matter back to the land. The benefits of returning the nutrients and the organic matter must be taken into consideration with other concerns.

“This first French conference on phosphorus recycling in agriculture showed the need for further dialogue between different Ministries, between science, farmers and industry, and with other societal stakeholders, in particular opening discussion with the agri-food industry. This should address the implementation of the nutrient circular economy (regulation, economy, logistics, organisation) and also the societal aspects of acceptance of organic residual use in farming (contaminants, risk assessment, image of secondary products).”  European Phosphorus Platform 2017

Given some of the concerns with returning biosolids back to the land, we have to respect that there are those that prefer incineration of biosolids as possibly a more acceptable alternative, however, there are also significant air pollution concerns with this practice (Fullana et al. 2004).

We need to work together to resolve some of these questions. Biosolids will be with us for as long as we are on this planet. One of the key strategies will be source control – to understand what we are putting in our wastewater, and the impacts that it has on our environment, both water and soil.

In the next posts, we will discuss pharmaceuticals and phosphorus in biosolids, their impact, and how we can work towards good management.


European Phosphorus Platform. 2017. Scope Newsletter.

Fullana, A.S., J.A. Conesa, R. Font and S. Sidhu. 2004. Formation and Destruction of
Chlorinated Pollutants during Sewage Sludge Incineration Environmental Science and Technol. 38: 2953-2958

Yoshida, H., C. Scheutz, and T.H. Christensen. 2014. Life cycle assessment of sewage sludge treatment and its use on land.


Composted Biosolids as a Fertilizer

Beneficial reuse of biosolids also includes using composted biosolids as a fertilizer. Biosolids are high in nutrients, particularly nitrogen and phosphorus. Given that phosphorus is required for all life to exist on this planet, and that there is a limited supply of phosphorus remaining, it is important to recycle phosphorus as we are able.

Biosolids can be composted on their own or together with poultry manure to produce a valuable fertilizer product. The advantage for the biosolids is that the composting process eliminates odour, potential pathogens as well as other emerging substances of concern present in raw biosolids. The advantage for the poultry litter is that the composting process eliminates potential pathogens as well as antibiotic resistant organisms. Given that next week (Nov 13-19) is Antibiotic Resistance awareness week, potential pathogens and microbial resistance is an important consideration.

Challenges with application of raw biosolids includes odour dispersion in the community, as well as a practical challenge of spreading the material consistently, particularly on grassland. Use of composted biosolids resolves many of the concerns, allowing phosphorus and other nutrients to be recycled.

Recycling biosolids, including the organic matter and nutrients, is an important step in encouraging a circular economy, where we understand that we are accountable for everything we produce or use, and that we recycle it in the best way that we can.

Composted Biosolids Excellent for Erosion Control

Using composted biosolids to minimize soil erosion is an excellent strategy to recycle biosolids and reduce the negative impact of soil erosion, which is one of the more serious environmental concerns that we have. Loss of organic matter is detrimental to the health and well being of our soil. Erosion of our soil leads to negative environmental impacts to the health of our waters and fish and other animals that live it it.

Grass seed was planted at the same time on the slope in the photograph. On the left, the grass has barely germinated, and on the right, the grass is flourishing.

A composted mulch reduces the potential for soil erosion in two ways:

  1. It reduces the impact of raindrops, which cause the soil particles to erode, and
  2. It promotes vegetation which further reduces the potential impact of precipitation on erosion.

Compost promotes vegetation in three ways:

  1. It prevents the soil from drying out as quickly, allowing seeds to germinate
  2. It shelters the seed, preventing it from drying out and failing to germinate
  3. It provides nutrients that allow the vegetation to establish.

Composted Biosolids – Beneficial Use as a Growing Media

We need to find beneficial uses for biosolids from our communities. Biosolids are produced in communities that implement wastewater treatment processes to reduce the negative environmental impact on our soil and water, including ground water, streams, lakes and our oceans. We will be producing increasingly more biosolids as our communities around the world improve their wastewater treatment.

Composting the biosolids is one way to eliminate potential pathogens, remove odour and stabilize the trace elements. It also appears to be the best process currently available that is most likely to eliminate some of the compounds of concern that enter our wastewater system.

When biosolids are composted with woody materials, the composted biosolids make an excellent ingredient for a growing media for ornamental and other plants in our communities. Its an excellent way to recycle organic matter and nutrients, particularly phosphorus, which is a finite resource.

Beautifying our communities with ornamental plants also benefits the wildlife in our communities.

As we think about reducing our negative environmental footprint, and improving our circular economies, recycling our biosolids as a growing media ingredient is one strategy that also beautifies our neighbourhoods!

Biosolids as a Source of Alternate Energy

Biodrying biosolids makes it much more practical to use as an alternate fuel, by reducing the moisture content and making it much more manageable to transport and feed into a burner.

Wastewater biosolids a product that we will only see more of in our world. As we improve our wastewater processes to dump less waste into our waters, including our streams, lakes and ocean, we will generate more biosolids. Worldwide, approximately 50% is recycled for agricultural uses, and a smaller percentage is incinerated or used as an alternate fuel.

Reusing the biosolids to our soils to provide nutrients and organic matter is important for the health of our soils, however, some are concerned about some of the chemicals that we put into toilets and end up in our biosolids. Incinerating the biosolids or using them as a source of alternate fuel is also not without environmental consequence. Some are concerned about the air emissions resulting from using biosolids as a fuel.

There are a number of challenges with using biosolids as a fuel source. Firstly, its 75-80% water, which makes it expensive to transport. Secondly, biosolids are sticky and lumpy, making it difficult to feed efficiently into a burner, Thirdly, a considerable amount of the energy in the biosolids is used up in the transport and drying of the biosolids before it can be used as an alternate fuel.

We tried biodrying biosolids and made a number of observations. The ability to biodry biosolids depends on the available energy in the biosolids, which is directly correlated with the amount of processing at the waste water plant. For example, one biosolids from a small community where minimal wastewater processing occurred allowed drying of the biosolids from 77% moisture to 28% moisture in two weeks. Contrastingly, a biosolids produced from a community with more extensive processing had little available energy resulting in minimal biodrying potential!

Biodried biosolids are much easier to transport and manage, and have available energy to be used as a fuel.

The resulting dried biosolids has a calorific value similar to brown coal. It is also much more transportable and simple to feed into a burner system.

Calorific values and proximate analysis of the biosolids biodried to 28% moisture.

Additional drying of the biosolids can be achieved if we used heat recovery or heat exchange. This is done at some biodrying facilities, and is a process that can be easily added. The present drying was achieved only with the energy already present in the biosolids.



Biodrying – Stabilizing and Processing Wet Organic Waste

There is a lot of wet organic waste produced in our society, including food and food processing waste, biosolids and animal manures. Moisture contents of these materials are often 75-80% or higher. There are at least three potential challenges with these materials including:

  1. High odor potential – many of the wet organic wastes do not have a pleasant odour, or are
  2. Material handling – many of the wet organic wastes are wet and sticky, and can be challenging to manage as it neither flows nor pours very well.
  3. Transportation – many of these organic wastes have excellent nutrient value, but must be processed before beneficial reuse. Transporting 80% water is not efficient.

Drying these materials for more efficient management is not economically viable in most cases.

There is a concept called biodrying that has been used successfully to dry and stabilize wet organic waste. Biodrying uses the potential energy in the organic waste to allow the moisture to evaporate. Let’s look at one recent example from our own work.

Temperature and airflow during biodrying of wet organic waste starting at 77% moisture and ending at 26% after two weeks.

We evaporated 80% of the water contained in the wet organic waste in two weeks, with 80% of it evaporating in the first week. The other interesting observation was that the organic waste, which started out as a highly malodorous material, had almost an earthy smell after biodrying.

In these experiments, there was no energy input of any kind, other than the energy in the waste. Incoming air was provided only by the vacuum caused by the self-heating of the organic waste – there were no air blowers.

Its a fun process utilizing principles of microbiology and physics!

Environmental Management in an Age of Antibiotic Resistance

In the time before Christmas, we hope, we anticipate. We hope for peace in our world, a place where we all can flourish.  We are thankful for the ways that we could participate in making our world a better place for all of us.

We are proud to be working with our communities of Abbotsford and Mission in a small but yet a very important and global effort to reduce the threat and cost of antibiotic resistance resulting from biosolids management in three distinct ways:

  1. By ensuring that the biosolids meet strict microbial standards before they are released.
  2. By advocating that Class B biosolids having high fecal coliform should be properly treated before entering our environment.
  3. By innovating and continually looking for solutions to better manage our biosolids, through composting or other technologies.

Some of the solutions such as composting not only reduce the risk of microbial resistance, but reduce other substances of concern by up to 99%. It also reduces cost of transportation as well as odour and other social concerns normally associated with landspreading of biosolids.

Investing in good management today reduces the health care cost for our children and gives us the satisfaction of knowing that we did our small part for our community and our world.

Importance of our environment in managing antimicrobial resistance (drawing from FAO website)

Importance of our environment in managing antimicrobial resistance (drawing from FAO website)

The health care cost of antibiotic resistance, or commonly referred to as superbugs, is expected to reach $ 100 trillion annually by 2050. The World Health Organization stated that “Antimicrobial resistant-microbes are found in people, animals, food, and the environment which include our water, soil and air.” They show up in hospitals because that’s where we end up if we are sick. Its also where people are more likely to be compromised, after surgeries, or cancer treatments.

How we manage our waste, our water and our food is important. They are all interconnected with our health.

Personally, I am thankful to utilize 30 years of training and experience in microbial ecology to work towards the well being of our planet.