I use these lines of code to remove all punctuation marks, symbols, etc as you can see them in the array,
$pattern_page = array(\"+\",\",\",\".\",\"-\",\"\'\
Depending on how greedy you'd like to be, you could do something like:
$pg_url = preg_replace("/[^a-zA-Z 0-9]+/", " ", $pg_url);
This will replace anything that isn't a letter, number or space.