From farm to table and back again

When you flush your toilet, you probably don’t think about the lab-grown bug in a vat of toxic sludge waiting to devour whatever you send its way.

It sounds like something out of an alien movie, and to those on this side of the toilet, it might as well be due to how disconnected we tend to be from the process, but it all happens just a few miles away at Morganton’s Wastewater Treatment Plant.

Eli Self, the plant superintendent, loves his job. In fact, morale and job retention at the plant are high across the board, he said, and workers often stay for decades

Self attributed this to the work being mostly outside and entailing light maintenance tasks.

“There’s always something to do out here,” he said. “always washing something down … keeping things repaired … mowing and weed eating … there’s a lot to do.”

But let’s get back to the bug.

The moment a toilet is flushed in Morganton, it goes underground into Morganton’s collection pipe system, Self said, which represents about 300 miles of piping.

Whether by gravity or strategically placed “lift stations” where the sewage is pumped out of low-lying areas, the contents of the flush eventually make their way to the treatment plant at the dead end of Vine Arden Road north of downtown Morganton.

First, Self said, the sewage hits a preliminary “bar screen,” a heavy filter that sifts out large debris like trash or rags. It is filtered again for rocks and sandy materials that are heavier than water.

After preliminary screening, the waste enters a huge holding tank with a metal drive that stirs the waste, using gravity to separate out the solids, he said.

The next step is to oxygenate the mixture and introduce a naturally occurring, microscopic bacteria — aerobic protozoa — that separates the sludge from the water, he said.

The protozoa, or “bug” as Self referred to it, uses static electricity to envelop the solids, creating a microscopic filter and squeezing the water through that membrane as it feeds on the bacteria in the waste.

“Given enough time in mixing, that bacteria creates a media that sticks to itself,” said Self. “When they settle, it creates a blanket that basically filters out all the suspended solids that can be in water … What you’re left with is clear water that you can disinfect really easily.”

During an onsite interview with The Paper, Self walked out on a gangplank above a huge vat of liquid — crystal clear water on top, and green-gray sludge on the bottom. He then produced a 15-foot-long clear tube with a stopper on one end, dipped it into the water, and using the suction from the stopper, retrieved a 10-foot sample of the contents of the vat.

Clear as day, the sludge took up a couple feet at the bottom, and everything above it was clear water.

“We call it a ‘sludge judge,’” he said.

Throughout the entire process, each step is subject to rigorous testing in the plant’s onsite lab, said Self. Workers could be seen in the lab with microscopes, droppers and test tubes ensuring the appropriate level of microbes in the mixture.

With sludge and water separated, the water is directed to another station where it is chlorinated and disinfected, then dechlorinated, then dumped into the Catawba River, according to Self. It’s not up to drinking standards, Self said, but it’s clean enough to be reintroduced to the river without harm.

But what about the sludge?

At this point in the process, Self said, the sludge has lost much of its stench and has an “earthy” smell, he said.

The sludge is then removed from the tank, compressed, mixed with woodchips, and stored with fresh air being forced through the pile with a blower, he said.

As the bacteria and other organisms begin to feed on that oxygen and the carbon in the woodchips, the pile gets incredibly hot, Self said, sometimes reaching up to 150 degrees Fahrenheit. This kills pathogens and keeps “good bacteria” alive, according to Self.

After about 90 days of this microbial war, workers screen the material to get heavy chunks out of the woodchips, and the lighter material is given to the public, free of charge, to be used as compost, said Self. They call it “Morganite.”

So that one flush, after journeying for miles through a pipe, is eaten by a bug, filtered, squished, superheated, and given back to you so you can spread it in your garden.

You might have just lost your appetite, but the bug never does.