At its height, 45 firefighters tackled the incident at Siteserv, Llandow Industrial Estate, near Cowbridge, which started on Tuesday at 19:20 GMT.
Now, crews are removing refuse and continuing to damp down the site, said South Wales Fire and Rescue Service.
It is thought they could remain at the scene for about a week.
Siteserv, which employs around 200 people, was set up more than 16 years ago by brothers Nigel and Philip England.
Earlier this week the company said it was working with investigators to help identify the cause of the fire.
The fire involved about 1,000 tonnes of mixed household waste.
Crews using two fire engines and a specialist aerial ladder are working at the site.
Firefighters remain at the scene of a Vale of Glamorgan recycling plant four days after it was devastated by a large blaze.