When it comes to clean water, the enemy of my enemy is my frenemy

Wednesday, April 02, 2014

Colourful Moving Bed Biofilm Reactors

A little while ago I was working at an information table for sustainability and so I had to gather information about the cool research we do here on campus. I asked a whole lot of uOttawa professors about their research regarding sustainable development, and I thought that the coolest out of all of them was that of Professor Robert Delatolla’s. What is so incredibly neat about Professor Delatolla’s research is that he uses miniature spaceships. Sold yet?

These honeycomb pasta like plastic thingies are mini-houses for bacteria that clean waste water. MBBRs (Moving Bed Biofilm Reactors – BUT FEAR NOT: you won’t need to remember this) are little bits of plastic that are designed to allow bacteria to grow in a community called a biofilm. These biofilms, or bacterial communities, filter the sludge in water by removing ammonia and nitrates.

There are a couple of reasons why I think this particular project is brilliant.

  1. We are using what bacteria use against us against them – muahahah! 
  2. This system has some serious staying power – literally. You can blast it with a fair amount of force, and it will stay. 
  3. It can handle our frigid Canadian winters. 

Using our enemy’s weapons against itself: 

As with anything, bacteria too are stronger in numbers. Bacteria living in biofilms can handle quite a bit of drama: extreme temperatures, antibiotics, agitation…which they could not do if they were living alone.  The thing is that generally speaking, biofilms usually complicate our lives. They can be found in sinks, sponges, teeth and in the worst examples, in catheters and implanted heart valves.

Biofilms create a slimy mess that is hard to clean up. But here is the trick; biofilms are the reason MBBRs work as well as they do. The bacteria want to stay in this community. So, the biofilms keep the bacteria inside the tank while polluted water runs through it with force and speed. Essentially, we just need to give them their daily dose of dirty water, and the bacteria are as happy as they can be and so are we with our ammonia-free water.

Here to stay: 

Biofilms are robust. They can withstand shock loadings. As the effects of climate change become more and more apparent in our weather patterns (I don’t know about you, but back in my parents’ day, spring began in March!), periods of drought and heavy rainfall seriously mess with the sewage system. The water that enters the treatment plants, as with our weather, becomes very moody. It can have too much sludge, not enough, and can come all at once. Biofilms can handle these fluctuations in both pollutant concentration, and water flow rates.

Cold times:

Most bacteria, just like you, have a sweet spot for the temperature they like to work at. Maintaining this ideal temperature becomes a problem if you live in the frigid snowscape we call our home. MBBRs are able to fix the ammonia at temperatures as low as 1°C, which is impossible in conventional systems. We don’t have to invest as much money into keeping the tank warm; and no one needs to supervise the bacteria every day to make sure they are doing their work (once in a while is probably good though!). In the end, we are reducing our carbon footprint and using less energy with systems using biofilms than others.

This is all to say that I’m happy that uOttawa is paying attention to our little frenemies, and that bio-engineering is paving the way for these brilliant sustainable practices!

~ rochelle - sustainability outreach coordinator

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