Hot Stuff in Landfills?

My spouse shook my world the other day!  A tedious conference call at work had her scrolling her Facebook feed, and, as she is a nerd like me, her feed has some great science stories. I was busy with my own biosolids science inquiry, so I was inclined at first to ignore her FB messenger notes.

But how can you ignore Records Found in Dusty Basement Undermine Decades of Dietary Advice? We all know a plant-based diet is the pathway to good health. But National Institutes of Health employee Christopher Ramsden had uncovered a trove of 9,000 patient files of a seminal nutrition study completed 40 year ago, the data from which, when reanalyzed, turned upside down the conventional wisdom that a diet high in saturated fats increased risk of deaths due to heart disease. The data showed the opposite!

What?! I have been eating bean burgers when my health would have been better served by beef burgers?

And, a short while later, another FB Messenger note from my wife excitedly urged me to read about plastic-eating waxworms. We all know that the health of soils and oceans, on which human existence depends, is ultimately doomed by accumulation of plastic, particularly of the micro kind.  But here the LA Times was announcing, in Stubborn plastic may have finally met its match: the hungry wax worm, “researchers set wax worms loose on a polyethylene film, watching holes appear after just 40 minutes… So far, the scientists are not sure whether this ability is due to the wax moth larva, or to the microbes within its gut.”  I went to Google Scholar to find, despite being a faithful reader of Engineering Science & Technology, I had missed an article back in November 2014 (Evidence of polyethylene biodegradation by bacterial strains from the guts of plastic-eating waxworms) announcing “the results demonstrated the presence of PE-degrading bacteria in the guts of waxworms and provided promising evidence for the biodegradation of PE in the environment.”

I should have known, gut bacteria are the heroes; they even eat plastic. Maybe humanity is not doomed, not yet at least, by plastic.

All of this “news” had distracted me from my own biosolids investigation of the bizarre. I had been uncovering a wholly unexpected adverse environmental effect of biosolids.  Let me hasten to say, there is NO FIRM EVIDENCE, not yet at least, that biosolids is responsible for this: Elevated Temperature Landfills.  

For the better part of 30 years I have held the firm conviction that biosolids co-disposal with municipal solid waste (MSW) is a win-win, filling in space-wasting voids in the emplaced trash, hastening biogas production and accelerating settling. Biosolids co-disposal is so beneficial for MSW landfills that it warrants a discounted tipping fee, I would argue (unsuccessfully so with landfill companies).

What I know is true, like plastic is forever and animal fat ruins hearts, may not be true!

Eminent emeritus Virginia Tech professor John Novak had first planted the doubt, which I mostly ignored. In his keynote presentation to the 2015 WEF biosolids conference, Dr. Novak darkly warned, almost off-handedly, against over reliance on co-disposal at landfills, as disposal challenges go beyond odors. In a casual follow-up conversation with Dr. Novak I first heard the phrase “elevated temperatures.”

There the matter lay, until the recent 2017 WEF Conference in Seattle. From another industry insider, I learned a research project had been launched to study Elevated Temperature Landfills (ETLF). This was no small investigation. Major companies had gotten together to fund it. A highly-credentialed team had been assembled. Some extraordinary situations had been reported by the press. 

I did some Internet sleuthing and followed with interviewing. The Environmental Research and Education Foundation, formed as a research arm of the solid waste industry in 1998, requested proposal to study ETLF in 2015, resulting in CCL receives Environmental Research & Education Foundation (EREF) funds research grant on elevated landfill temperatures.  This team is led by Dr. Marco J. Castaldi, an engineering professor at the City University of New York (CUNY) and includes Dr. Morton A. Barlaz, professor at North Carolina State University.  A PowerPoint presentation posted by Dr. Barlaz, Heat Generation and Accumulation at Municipal Solid Waste Landfills Experiencing Elevated Temperatures, provides eye-popping descriptions of ETLF at work and the importance of the new study.

A Google search points to at least one shocking situation. The online waste industry publication Waste360 has tackled this topic, first with a March 2016 overview ( Elevated Landfill Temperatures a Concern for Operators ) and then with a three-part series of articles on elevated temperature landfills ( Diagnosing and Understanding Elevated Temperature Landfills ).  In November 2016, Waste360 provided  The Bridgeton Landfill "Fire" Explained (Updated), in which the story of the St. Louis, Missouri, landfill owned by Republic Services, is described.  This is already national news, albeit National Public Radio:  Landfill Fire Threatens Nuclear Waste Site Outside St. Louis.  According to the NPR article, “Specifically, Acting EPA Regional Administrator Mark Hague says there is "no imminent threat" of the underground fire in what's known as the Bridgeton Landfill reaching the radioactive waste at the adjacent West Lake Landfill.”

Do you feel reassured?

Another research team in Louisiana is “hot” on the trail of symptoms and causes of elevated temperature landfills. Navid H. Jafari is the lead author of Spatial and temporal characteristics of elevated temperatures in municipal solid waste landfills. The authors state: “In particular, MSW landfills undergo changes in behavior that typically follow a progression of indicators, e.g., elevated temperatures, changes in gas composition, elevated gas pressures, increased leachate migration, slope movement, and unusual and rapid surface settlement.”

So far, no mention of biosolids in on-line PowerPoints or by the media.

Nevertheless, the hallway conversation in Seattle turned to a recent tragedy at Greentree Landfill in Kersey, PA, this past February.  One article among many is Worker’s Body Found After Being Buried In Trash At Pa. Landfill.  The speculation heard in Seattle is that the surface instability at Greentree arose from a “hot spot” associated with a high proportion of biosolids disposal accepted at this landfill. 

When Waste Management, Inc., (WM) took steps in February 2015 to change its policies on biosolids acceptance, the principal assumption was its impetus was odor complaints.  That this step should apply to WM’s Pennsylvania facilities seemed to be reasonable (Pennsylvania Orders Waste Management to Close Tullytown Landfill by 2017). After all, NYC DEP, a major customer at the time, does not certify its biosolids as compliant with Class B pathogen standards or with Vector Attraction Reduction standards, and Pennsylvania regulations seem to require this level of stabilization for landfill acceptance.

But WM’s policy on biosolids co-disposal may include other considerations – for instance a risk of elevated temperature.  A recently retired WM engineer explained in a recent interview that no WM landfills receiving a proportion of biosolids lower than 10 percent of daily trash acceptance had displayed problems with elevated temperatures. While this is not a basis for a cause/effect relationship, if you are a landfill operator a reasonable course of action is to impose a 10% maximum acceptance rate for biosolids. That is what WM did in 2015.  Other landfill owners, including Greentree’s, did not.

But how could biosolids be involved with elevated temperatures?  In Waste360’s  Diagnosing and Understanding Elevated Temperature Landfills (Part 3), the authors suggest the reaction is  “Pyrolysis… the thermochemical decomposition of organic matter at elevated temperature in the absence of oxygen.”  As a follower of the WE&RF LIFT program, I recalled the proposal from a start-up enterprise, HydroTORR’s ZIP-Carb (Zero Input Process Carbonization), deploying hydrothermal carbonization (HTC), a wet-state thermal decomposition under elevated temperature and pressure in an oxygen starved environment, very pyrolysis-like.  That modern landfills are hundreds of feet thick, totally insulated, oxygen-free and wet with recirculating leachate, internal conditions are seemingly consonant with HTC.

One researcher involved with HydroTORR is Dr. M Toufiq Reza, formerly of University of Nevada, now at Ohio University, Athens. He has a specialization in “applied bioenergy.” When I put my hypothesis to him, Dr. Reza gave it a few hours consideration and in an email back to me suggested that high strength leachate combined with biosolids sealed in waste cells under pressure “might go for an exothermic decarboxilation reaction resulting in CO₂ and heat.” These are the two key indicators of elevated temperature landfills.  

The science is still not there to link biosolids and elevated temperatures, at least not yet. But, if science can surprise me with contrary conclusions on plastic and lard, it can surprise me with contrary conclusions on biosolids in landfills.

I participated in the March for Science in Philadelphia on Earth Day. It was a perfect venue for me to recommit to keeping science front and center with biosolids. Dr. Reza wrote: “To test the hypothesis, I may need to test the leachate sludge and aged-sludge.”  He stands ready to do some research, and I invite you to join me in elevating the SCIENCE OF HOT BIOSOLIDS.