M.J.
I can tell you from personal experience it's next to impossible to stop a biter. I was sitting right next to my daughter on the floor when a friend bit her. Looked at her owie, sat down again and chomp, yet again! I couldn't react fast enough to stop it, even being right there looking at everything going on. I know it's easy to blame the teachers or want them to do more, but there truly is only so much they can do.
Biting is super common at this stage. I know from experience it's not fun having it happen to my child (one time she had a mark for a full week from a child at daycare biting her), but also know that it's not the sign that this other child is evil or that my child will get some strange infection or be scarred for life. It's just one of those things that happens at this age, whether in daycare or at the park or at a friend's house.
Once kids are more verbal and can express their feelings better, you'll see far less biting, I promise. But changing daycares or asking the other child to do that won't eliminate the situation. You may just end up around another biter or a kicker, hitter, pincher or spitter in the room instead. This is a tough age group, but again, it gets better once they're talking.
Hang in there!