Well a popular one is the dishwasher sans soap.
Another option is a bathtub or a rubbermaid tote of some sort.
Some people use saltwater to kill the baddies and some use bleach water. The key is to scrub all of the dirt off, peel any loose debris off and get it as clean as you can.
An alternative to scrubbing is to use a pressure washer or a coin fed car wash with the high pressure spray.
To "plant" it, screw it to a piece of slate or weigh it down with rocks until it stays at the bottom. Usually it'll take a few weeks.
Good luck and take pics!
If you know someone with a sandblaster you can have them blast it which will clean and sand the wood.