How to dispose of paint waste water...
We can all agree that protecting our water sources is vital to our health and that of the planet. Here are two easy ways you can keep those harmful chemicals and microplastics out of our waterways. Please keep in mind these are not perfect solutions (we’re still searching for those!), but they are best practices based on what we have available as of 2022.
Evaporation Method
Collect dirty paint water in a medium container at the end of each week or session (your preference). *Remember you don’t need as much water as you think! More on that later.
Let paint solids settle. Water will naturally separate from the plastics in the paint and rise to the top.
Gently skim clear(ish) water from the top and place in a second bucket. You can filter this water through an old bit of nylons or cheesecloth and then dump the remaining water.
Leave remaining dirty water in the medium container to evaporate until completely dry. Make sure this is in a safe spot away from children and animals. Or place an old nylon over a lid with a hole in it to keep unwanted people and animals out of the dirty water.
Once it’s dry you can peel the paint out of the container and either dispose of it or see alternate options below.
Flocculation Method
Check out this video for a detailed step by step process. I’ve also included a great how to graphic from Golden.
Instructions:
Start by assembling the supplies listed below. Decide on the process batch size. Using 5 gallon pails allows you to process up to 2½ gallons at a time. A 1 gallon pail and matching funnel allows for up to a ¾ gallon batch.
Add 10 grams of granular aluminum sulfate for each gallon of water. This is about ½ Tablespoon, well rounded. So, 2½ gallons would require about 25 grams, or 1¼ Tablespoons. Dissolve this material in a small jar with several ounces of water before adding to waste water. Then, add to waste water and stir vigorously.
Add 9 grams of powdered lime per gallon being processed (a scan ¾ Tablespoon). Stir in vigorously and observe. The flocculation of solids should start occurring within a couple of minutes. You should start to see a clear layer of water forming very quickly as the solids settle to the bottom. If, after several minutes, flocculation has not occurred, repeat steps 1 and 2.
Check the pH of clear water. It should be between 5 and 9. If lower, adjust by adding lime, If higher, adjust by adding aluminum sulfate.
Assemble the filtering equipment as shown. Use 2 coffee filters at a time. Pour the water through the filters after flocculation has occurred. The water will take several hours (over night) to completely pass through the filter. The resulting filtrate should be clear and should be flushed to a sanitary sewer. The solid filtered residue should be disposed of in a licensed landfill.
what do you do with the dried paint waste??
Dispose in the garbage
Check with local waste disposal facilities to see if they will accept it
Save it to use to make sculptures or mixed media designs