replacement

<?php

function replace_content($content){
    $content = str_replace('&#8220;' , '&laquo;',$content);
    $content = str_replace('&#8221;' , '&raquo;',$content);
    $content = str_replace('&szlig;', 'ss',$content);
    $content = str_replace('&#7838;', 'SS',$content);
  return $content;
}
add_filter('the_content','replace_content');