All you really can do is keep banning his IP, email address, and name he uses each time he does this.
Eventually he will get bored with it and go away.
I'ld suggest you do not add fuel to the fire - in other words if he makes it on, posts anything inflamatory - delete the posts - dont reply to them. You only continue this further by doing so as he wants to aggravate you. If you let him - he wins.
-sibyls tip for the day