I assume the sink is currently plumbed so that both sides drain into your waste line? If so, just re-plumb it so only the one side goes to the waste line. On the parts washer side, plumb it straight down (assuming there’s room to have it go straight down) into a bucket with a lid. Put a rubber grommet into the lid to fit tightly around the drain pipe. Grommets for the discharge from the pump and power cord too. Google parts washer spout and buy one of those, along with a pump obviously. Drill a hole in the rim of the sink to mount the spout, plumb it to the pump and voila, you’ve got a parts washer. Keep a stopper in the drain when not in use to keep water or other contaminants from getting into your PW solution. Maybe cut a board or piece of sheet metal to sit on top of the sink to keep stuff out too. Add a couple blocks to the underside of it to keep the sheet from wanting to slide sideways.
