This is a little hard to understand out of the context of the whole text this paragraph comes from. 'To render', in this case, means to offer a service. Rendering facilities throughout the U.S. offer varied services including pick-up services for animal carcasses and onsite euthanasia. So it's guy who picks up deceased animals and transforms them in to different things. The process produces a variety of products including tallow, lard, animal feed, protein meal, cosmetics, and mechanical lubricants. Interesting! Thanks for sharing.