未经许可的uri删除char后，CodeIgniter重定向URL

I'm working in a CodeIgnitier project. We have many data with a wrong configuration so many URL contains unicode chars and others undesirables chars. Clean all data will take several months and I want to avoid 400 errors due to permitted_uri_chars. The ressources are accessibles if I remove undesirables chars. I would like automatically remove these chars. I try to put the following code in application/config/routes.php :

if ($this->uri->total_segments()) {
  foreach (range(1, $this->uri->total_segments()) as $i) {
      if ($this->uri->segment($i)) {
          $this->uri->segments[$i] = preg_replace("#[^".$this->config->item('permitted_uri_chars')."]#i", "", $this->uri->segments[$i]);
      }
  }
}

But I get the 400 error. CodeIgniter controls URLs before passing in routes.php. Where can I put my code to avoid 400 error ? Can I do that in pre_system hook ?

Please understand this code and put on top into your header file. You can manage your url as you want.

$id = $this->uri->segment(3);

if($id)
{
    $url = str_replace('/'.$id,"",$_SERVER['REQUEST_URI']);
} else {
    $url = $_SERVER['REQUEST_URI'];
}

$pattern = '/([A-Z]+)/';
if(preg_match($pattern, $url))
{
    $new_url = strtolower($url);
    Header( 'HTTP/1.1 301 Moved Permanently' );
    if($id){
        Header( 'Location: ' . $new_url.'/'.$id );
    } else {
        Header( 'Location: ' . $new_url );
    }
    exit;
}

I use a solution to avoid 301 redirections. I don't want Google hate me because I send sitemaps with several 301 redirections. I allow certains chars but remove these in routes file.

In my config.php file :

$config['permitted_removed_uri_chars'] = '\',ß';
$config['permitted_uri_chars'] = 'a-z 0-9%.:_\-+&'.$config['permitted_removed_uri_chars'];

In my routes.php files :

if ($this->uri->total_segments()) {
    foreach (range(1, $this->uri->total_segments()) as $i) {
        if ($this->uri->segment($i)) {
            $this->uri->segments[$i] = preg_replace("#[".$this->config->item('permitted_removed_uri_chars')."]#i", "", $this->uri->segments[$i]);
        }
    }
}