Yvonne Carts-Powell

Hilarious and useful: Poo-Gloos eat sewage — interview

In hilarious, Science on January 12, 2011 at 1:00 am

They look like igloos and they eat poo. Poo-gloos sit in an unfilled sewage lagoon in Plain City, Utah, before the lagoon is filled. A new study shows the devices can clean up sewage as effectively as multimillion-dollar treatment plants, and thus can help small, growing towns and cities save money. Credit: Waste Compliance Systems Inc.

Monday’s post was about happy children and flowers. Today’s is about poop.

I interviewed Taylor Reynolds of Wastewater Compliance Systems, Inc., about the company’s “Poo-Gloos”. (Okay, they’re actually being sold as “Bio-Domes” but they look like igloos and they eat poop. Take a look at the second figure.)

The inner workings of a poo-gloo. Each poo-gloo includes four nested domes with plastic packing (wagon wheel shapes) between them to provide a large surface area on which sewage-eating bacteria grow. A hose (red) sends bubbles (gray circles) upward through the poo-gloo, and the air helps pull wastewater up through the device (blue arrows). Credit: Waste Compliance Systems Inc.

ScienceofHeroes: How heavy is a bio-dome? Do they need to be anchored to stay down?

Taylor Reynolds: The standard bio-dome weighs just under 900 lbs. They do need to be anchored so we mount them on concrete bases that provide enough weight to keep them from floating.

ScienceofHeroes: Why this size? Is there some sweet spot to the 28 square feet size? Could smaller/larger versions be used?

Taylor Reynolds: The size is a function of industry standards. Most wastewater lagoons are between 6 and 8 feet deep. The poo-gloos are 5 feet tall and 6 ft in diameter, so that once installed they will have a minimum of 1 foot of water covering them. In other applications we can and do manufacture other sizes to meet the needs of the system. There is nothing magical about our “standard” size other than to ensure it remains underwater.

[Poo-gloos are useful because they can be used in open sewage lagoons  to process  waste water. The intended users are small communities that are outgrowing the capacity of their sewage lagoons. Until now, the only alternative for these communities was to replace lagoons with expensive mechanical treatment plants.]

ScienceofHeroes: What is the bio-dome’s expected lifetime?

Taylor Reynolds: The expected life of a bio-dome is 20 years, although with proper maintenance they could last much longer.

ScienceofHeroes: How do they fail? Do they get fouled (so to speak) to the point where air can’t get through?

Taylor Reynolds: How do they fail? To date, the only failures we’ve had have been air distribution hose failures. Our first poo-gloos utilized a sponge rubber hose that had tendency to foul with mineral deposits and bio-film. We’ve since switched to a flexible PVC hose with micro-slits down both sides to allow bubbles out and we haven’t had fouling issues with it. The other major concern most engineers have is bio-fouling. When essentially the bio-film gets so thick, it plugs the poo-gloos. While theoretically possible we haven’t had an issue with it. Our theory is that the air bubbles create a micro scouring effect that knocks old growth off, which eventually falls out the bottom. We only install poo-gloos in “secondary” ponds where suspended solids are not an issue. We have another model that goes in primary ponds where suspended solids are present, but it doesn’t have packing, instead we increase the number of shells from 4 to 7.

ScienceofHeroes: What does one do with a “dead” one? Ship it off with the sludge?

Taylor Reynolds: If it does experience some sort of failure due to plugging, or air distribution hoses then we can replace / clean it and put it back into operation. The only time we have to completely dispose of a poo-gloo is when it is “broken” due to falling during maintenance, being run over by a boat or some other issue where the domes are compromised. Disposal then becomes the responsibility of the community, but they can safely be disposed of at a landfill or possibly even recycled.

ScienceofHeroes: Back at the visceral end of the story: What sort of gasses are emitted?

Taylor Reynolds: When treating the water for nitrogen based compounds the two primary gas products are N2, and CO2. The N2 generally escapes into the atmosphere, but the CO2 is consumed again as some of the bacteria need a source of carbon. I’ve attached few pages that show the reactions for both nitrifying (ammonia into Nitrate) and denitrifying (nitrates into N2) bacteria.

ScienceofHeroes: Do they stink?

Taylor Reynolds: No. Any time you add aeration to a wastewater lagoon that significantly reduces the amount of H2S escaping into the atmosphere and by consuming the ammonia we’re eliminating the other major contributor to wastewater lagoon odor issues. A properly operated lagoon should not be distinguishable from a pond to the lay person.

Copyright 2011, Yvonne Carts-Powell

Wastewater Compliance Systems, Inc.,
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  1. These things look like where Dufflepuds live.

  2. lol “poo-gloo”

    But these are really neat!

  3. […] subject, one that is always with us, and as close to our hearts as our large intestines. Like the PooGloo before it, this technology tackles our […]

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