It’s a sticky, rubbery, tar-like material known officially as “black goo” — and it’s showing up in landfills across the country including at the Greater Lebanon Refuse Authority.
“It clogs up the screens and filters used to catch particles going into our pipes from leachate lines,” said GLRA staff engineer Jim Zendek. “We have to do a physical cleaning of the lines in order to get rid of it, and it’s not a trivial process.”
Not visible on the surface, the goo is within the landfill’s system of lines, pipes and pumps that remove the leachate or liquids created as part of the decomposition process. Zendek is quick to caution that the goo is not released into the environment but stays in GLRA’s leachate system.
Zendek first noticed the goo in pipes about five years ago. Initially, it occurred sporadically. Now it appears more frequently. This month, GLRA will try a new tactic to deal with the goo — having the leachate lines jet cleaned with water to break up and remove the goo before it gums up filters.
“It’s absolutely become more and more common — maybe 100-fold in the last five years,” said Ryan March, partner vice president for Leachate Management Specialists and founder of FlowScience, in an email about the goo. March presented on black goo at Keystone Solid Waste Association of North America’s annual Joint Fall Conference in September in Harrisburg.
“About nine years ago, it was only a problem at a very few landfills,” he added.
The Chester County Solid Waste Authority began contending with the goo about three years ago, said Bob Watts, executive director, in an email. So far, only two of the authority’s 10 landfill cells are having issues with the goo, he added.
Besides modifying strainers so they don’t clog as quickly, the Chester County authority pulls pumps quarterly to clean them, Watts said.
Like Chester County, GLRA is fortunate to be dealing with limited quantities of the goo. Some landfills have reported pumps clogged by black goo in as few as six hours, according to industry reports.
Since it appeared in the early 2010s, university researchers have been studying the black goo using samples sent by landfills — including GLRA — to determine both what it is and how best to get rid of it.
They have found that despite variation in landfill locations, the goo has a similar physical appearance and a similar chemical structure. Chemical analyses indicate that the goo’s molecular structure is similar to that of sodium polyacrylate, a synthetic polymer common in a broad range of manufactured products including diapers, pet pads, meat pads and hygienic pads.
Super absorbent polymers (SAPs) also are used in personal care products such as nail polish, sunscreen, freezer gel packs, laundry detergents, packaging for eggs, and soil conditioner for retaining water.
As many as 12.2 billion tons of SAPs were produced in 2020, although March said the amount could be higher depending upon how polymers are categorized under commercial plastics production.
Goo also has been found to contain a high organic or biological content — between 45 to 80 percent, according to university researchers. That, in combination with a landfill’s anaerobic or oxygen-free environment, may be what turns the polymers in products such as diapers, meat pads and pet pads into goo.
“It has a great deal to do with where the discarded waste ends up in the anaerobic environment and the microbes that are present and constantly evolving to degrade matter,” March said.
While there is growing consensus on what black goo is, less is known about how to deal with it.
GLRA has conducted in-house experiments to break it down, Zendek told the authority board in September. Dousing the goo with hot water was successful, as was using hydrogen peroxide. Neither, however, is practical on a large scale.
“We want a solution,” Zendek said. “The more you analyze it, the more you know where it comes from so you can attack the source or eliminate it.”
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