Replace %20% with dash in url

Question

hello, i am working on ecommerce project. please sugges me how i replace %20% from url with dash to make my site seo frndly. 

 

my exiting url - http://XXXX.com/xx-xx-details.aspx?product_id=Balaji%20Creation%20Bed%20Sheet%20PURPLE

 url format that i want -  http://XXXX.com/xx-xx-details.aspx?product_id=Balaji-Creation-Bed-Sheet-PURPLE