TNRD – ‘Don’t put all your eggs in one basket’ on biosolids, experts urge

Elected officials and public listen to advice on biosolids. (Image: Mel Rothenburger)

Director, Electoral Area P, TNRD

The Thompson-Nicola Regional District shouldn’t rely on just one method for getting rid of sewage sludge, experts told a workshop attended by about 60 people on Friday (July 20, 2018).

The residual material left after sewage treatment is also known as biosolids, and it’s become increasingly controversial in recent years due to concerns about toxic contaminants and odour.

“When you’re doing your planning you need a basket of options,” Rob Simm, an engineer with Stantec, told the day-long workshop that included members of the public as well as elected officials.

He said changes in science, land availability and the market make it essential to “not put all your eggs in one basket.”

The workshop was organized as the TNRD and its member municipalities struggle with the issue of a long-term plan for alternatives to disposing of biosolids on land.

Land application, especially on agricultural land, is the most common use for biosolids. When pressed for an opinion on which disposal method carries the least risk to public health, Dr. Lalith Liyange, another Stantec engineer, said thermal technologies such as gasification are the most effective at killing pathogens.

But both he and Simm cautioned that it’s also more expensive than land application, and that each technology must be considered in the context of such things as transportation costs and which materials are mixed with the biosolids.

When he said the risks from land application appear minimal based on available knowledge, Kamloops director Denis Walsh commented, “You’re saying they’re minimal but you don’t know what they are.”

They said land application provides an opportunity to take advantage of the economic value of biosolids for such things as soil enhancement and land reclamation.

Sim and Liyange explained the various types of biosolids treatment such as aerobic, liquifaction and incineration.

The more processing that’s done the more options there are for what to do with the resulting biosolids, they said. However, the more water that’s removed from the sludge, the more energy is needed.

Various technologies are in a range of development from very early stages to well-tested.

Laurie Ford, an engineer with the Metro Vancouver Regional District, said her district is looking at various technologies to create dry biosolids. Considerations include cost, greenhouse gas emissions and volatility.

“We haven’t found that silver bullet yet,” she said.

The TNRD will follow up on the workshop with further discussion at a later meeting.

About Mel Rothenburger (8126 Articles) is a forum about Kamloops and the world. It has more than one million views. Mel Rothenburger is the former Editor of The Daily News in Kamloops, B.C. (retiring in 2012), and past mayor of Kamloops (1999-2005). At he is the publisher, editor, news editor, city editor, reporter, webmaster, and just about anything else you can think of. He is grateful for the contributions of several local columnists. This blog doesn't require a subscription but gratefully accepts donations to help defray costs.

1 Comment on TNRD – ‘Don’t put all your eggs in one basket’ on biosolids, experts urge

  1. “Don’t put all your eggs in one basket” How does this apply here? Either you accept some form of land disposal or you move to a cleaner greener option like gasification or pyrolysis. Author Lidia Epp (manager of the Molecular Core Lab in the Biology Department of College of William and Mary in Williamsburg speaking to the House Democratic Committee Hearing – 08/29/2016) describes the very REAL Problem with the land disposal option –

    “There is little doubt that there are direct human health consequences of land application of sludge. Several published public health reports clearly link the sludge application sites to the overall decline of health by the surrounding communities. Czajkowski et al in a publication from 2010 “Application of GIS in Evaluating the Potential Impacts of Land application of Biosolids on Human Health” concludes that there is a statistically significant increase in ill-health symptoms and diseases near the biosolids permitted fields. Exposed residents were defined as those living within the one mile radius of filed applied biosolids, the illnesses included certain respiratory, gastrointestinal and other diseases.”

    It is evident that the long term exposure to a host of the environmental pollutants is the foundation of many chronic conditions that are now at the epidemic levels. Rather than focusing narrowly on determination of specific sets of toxins present in biosolids from different sources – the research needs to shift to the epidemiological studies assessing the overall impact of complex mix of pollutants present in sludge.

    It is true that biosolids contain beneficial elements like phosphorus, nitrogen, organic matter and trace nutrients. But the benefits derived from introducing those components to the soil via biosolids are by far overshadowed by the detrimental effects of toxins and pollutants that comprise the vast majority of the biosolids content.

    Many countries adopted and implemented a new approach to the disposal of biosolids; methane production, energy source, recovery of metals and microelements. It is well past the time when we start to look at those alternatives as the only sustainable solution to the growing problem – what to do with the sludge our society produces.”

    While gasification or pyrolysis may be more expensive in the short term it is far greener, cleaner, and in the long run will pay for itself by energy creation, saved trucking costs etc.

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