Therisa Timan from Pittmetals B.C. wants to know what to do with her old paint cans. How do you handle paint waste responsibly?
If you dump solvent wastes like paint and paint thinners down the street drains, they usually go straight into the lake or rivers. If you dump it down the household drain it first messes up the city water treatment plant, and then gets dumped into the lakes and rivers. Essentially you shouldn't dump paint down a drain and you shouldn't even clean the brushes in the sink letting paint and solvent flush away.
We visited the city of Toronto water treatment plant to find out just what happens when solvents are encountered. It was fascinating following the various steps of cleaning up waste water.
At the Ashbridges Bay Water Treatment Plant, they first have Bar Screens to remove large rags, even logs that head their way. Then there is a grit removal chamber where they catch grit and sand. The Primary Clarifier chamber removes floating scum and sludge that settles in the bottom. Then the water flows into the Aeration chamber, third photo above. The bubbles cause bacteria to grow and consume most of the waste, leaving pretty much clear water and an 'activated sludge', seen in the second photo. The activated sludge can actually be used to seed the process again, just like with yogurt. The clarified water is then chlorinated and sent out to the lake. But unfortunately, most of those solvents are still there, the bacteria can't handle solvents. So all the solvent you are pouring down the sink, you are feeding to the fish!
So, how do we clean up after painting without polluting? Latex paint is fairly easy. If you have a small quantity left, just let it dry and then throw the can into the metal recycling. If you have a lot left, either use a Jell Hardener which will solidify the paint as you can see in the last photo. You can simply put the paint into the garbage and the can into metal recycling.You could also take it to a recycling plant or transfer station, but latex paint is not considered hazardous waste.
For oil paints, wipe the brush as dry as possible to minimize the quantity of solvents you will need to use to clean the brush. Pour solvent into a can and clean in the can, not by pouring the solvent over the brush. You could even use two cans, the first for getting the worst off, the second for final cleaning. When finished, to recuperate the solvent, particularly easy with Lacquer thinner, simply close off the can, let the particles settle to the bottom and then pour off the clean re-usable solvent into a clean container. The sludge should be collected for the annual hazardous waste collection. If not recycling then pour all waste, mixed together into one can labelled 'Waste' and when full, take to a hazardous waste disposal centre or Transfer station.
Some municipalities are equipped to actually recycle some paints, producing a lower grade but useable base paint.
To get oil off the driveway without flushing solvents into the storm drains, use a bio-degradable de-greaser like Oil Lift. This amazing product will allow you to soak up the mess and dump it on the grass -- really! It breaks the hydrocarbon chains of the oil and makes it bio-degradable. The bacteria in the grass will eat it -- just like at the water treatment plant.