PHP: Dynamic slug function with SEO improvements

seo_slug.php

<?php
/**
 * Used to give the full hyperlink for dynamic items
 *
 * @param $type string - events/news
 * @param $id int - ID of item for link 
 * @param $title string - item title for link to strip bad chars
 **/
function seo_slug ( $type, $id, $title ) 
{
	// strip bad chars
	$slug = trim(strtolower(preg_replace("/[^a-zA-Z0-9\s]/", "", $title)));
	$slug = str_replace('  ','-', $slug);
	$slug = str_replace(' ','-', $slug);
	
	return '/'.$type.'/'.$id.'/'.$slug.'/';
}