For pre anodize we deburr in ceramic triangles too worn for steel then into a second tumbler with 3mm ceramic balls, they come out bright and shiny, almost polished. the waste water from each machine runs through a 5 gallon bucket for settling tank and the water comes out clear with soap bubbles and into the septic. We use about a gallon of scalding hot water per cycle and 3 gallons at the end of the day to rinse the machine. The water that comes out of our tumblers is quite a bit cleaner than what comes out of clothes washing machine. I typically rinse the parts that are going to be tumbled when they come out of the machine to remove the coolant residue and small chips, I dump the rinse water back into the machine. If you start with clean parts, use clean hot water and minimal soap there isn't much of anything in the water that comes out of the tumblers, however if you put dirty chip/coolant covered parts in then you need more soap as the soap and oil cancel each other and create black goo that sticks to the media and slows down the de-burring compounded by the use of cold water. We have a 1.5 gallon 120v water heater mounted to the wall between 2 tumblers. We had a lot of problems with the process when we had employees as they would claim they followed these steps when in reality they put dirty, oily, chippy, parts in with cold water and complained about the results, grayish ugly parts and having to use too much soap and clean the media too often.
Great info! Thank you!