Posts Tagged ‘sewage’

The Sewers of Mactown

December 16, 2009

One of the notable things about McMurdo is the fact that, unlike most cities, it doesn’t have dumps or landfills. Everything that comes in, must go out. This includes discarded candy wrappers, soiled paper towels, discarded aluminum cans, old clothes, defunct equipment and—as you might have guessed from the title of this post—used food, or in other words, sewage.

This wasn’t always the case. Up until recently, McMurdo dumped its sewage into the sound, untreated. That mountain of human waste is still there below the water, incidentally providing a nutrient bonanza for the creatures living on the ocean bottom. There’s a poster or two in Crary Lab about the changes in the marine life communities of the sound since they stopped dumping waste and it began to return to its natural state.

Around 2002, however, the US Antarctic Program decided that this practice just wouldn’t do for a civilized member of the international Antarctic community, and so they set about installing a sewage plant. The plant was “test-built” in the US before being shipped down, just to make sure that they could get it set up smoothly during the brief Antarctic summer. It’s been up and running for a while now, and happily it is easy for the curious (such as myself!) to get a tour.

Here’s the holding tanks. The basic idea, as the plant manager explained it to me, is to set up the temperature, aeration, and so on to create a microbial paradise, so all the things already living in the waste can finish processing it. The foam is, evidently, created by a troublesome microbe that wouldn’t normally be there.

Roiling lakes of waste. There are three, of which you can see two in this picture.

I believe the orange thing is just a float to monitor the water levels.

Sewage comes in through pipes (which are heated, of course, so they don’t freeze) and then goes through two macerators–giant superpowered shredders–to break up anything that might clog the works. They’re just visible in the background here.

Evidently these are called 'Muffin Monster' grinders.

The sewage spends some time in the tanks, being merrily digested by enormous hordes of bacteria, before it’s decanted into the press room. Here, the sludge is loaded onto this belt to have more water pressed out of it. The water is filtered and goes back into the Sound–it’s actually more than clean enough to drink, by the time the plant is through with it, but they don’t use it for that purpose (it’s the squick factor, I guess.)

It's like a printing press, only different.

The pressed sewage–which is, somewhat misleadingly, called “cake” at this stage–is sent down a chute into enormous boxes that hold a quarter-ton each; they end up with 12-16 tons of processed sewage each season. The boxes get sealed up and shipped back to the States for disposal.

This tour brought to you by Aperture Science.

At this point it just looks like rich soil, and indeed if you look at a box that has been there for a few days you’ll find tiny sprouts growing–a result of seeds that have passed through the digestive tracts of McMurdo’s residents and come through the sewage-treatment process intact. The manager tells me these are tomato plants.

Aren't they cute?