Field of Science

CSWA field trips: 1. Calgary's new sewage treatment plant!

(This post will be followed by two others, on the field trips to Banff and to the Alberta oil sands.)

A big part of the Canadian Science Writers Association meeting was its field trips.  The first one I went on was to Calgary's new Pine Creek water treatment plant.  (Yeah, I'm a microbiologist so I love this stuff.)

Calgary is very proud of this plant, but they haven't yet gotten around to making it easy to find.  Signage is almost non-existent and there's no website (just pages with planning docs), so our old yellow schoolbus drove back and forth for about an hour searching for it (many PhDs with many iPhones were pretty useless).

Calgary gets its water from its two big rivers, the Bow and the Elbow, and it puts all its treated wastewater into the Bow.  (The Historic Park where we'd had our banquet the night before included a short paddlewheel ride on the Elbow-fed Glenmore Reservoir.  Coming from Vancouver, I was first surprised that boats were allowed on the reservoir, and then shocked at the muddy (completely opaque) state of the water.  I guess they have a really good filtration system.)

The city's other water treatment plants leave a lot of nutrients (e.g. nitrogen, phosphorus) in the treated water; these can stimulate unwanted algal growth in the river downstream.  The goal of the new Pine Creek plant is to put water into the Bow that contains no more nutrients than the river water.  It does this by some clever microbiology that I didn't understand.  My lack of understanding isn't the fault of our guide, an engineer who gave up his Sunday afternoon to lead us around.

But the information we got was just enough to be tantalizing - bacteria in one fraction of the sewage ferment nutrients (?) to produce volatile fatty acids, which are passed over to another fraction where the bacteria do something else (maybe just multiply?), using the fatty acids as an energy source.  Then this fraction, with its bacteria (?), takes on the job of removing the phosphate and nitrogen from the water(?).  At the end of the line the remaining bacteria and other organisms (stalked ciliates, rotifers...) are killed with UV, so that the water being released into the Bow River has few nutrients and no more than 200 coliform bacteria per 100 ml.  I think that the bulk of the nutrient-gobbling bacteria were removed from the water by a filtration step that uses plushy white mats, and then sent to the tree farm that's associated with the treatment plant, where their nutrients provide fertilizer.

I think I need to do another tour, where I ask all the questions I didn't ask in Calgary.  But I don't think any of Vancouver's treatment plants are up to their standard.

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