Puppy won't stop biting!!

Okay, first off, this isn't my puppy. I volunteer at a no kill animal shelter with my mom. All the dogs are great....then there's Daisy. She's a 10 week old Rottie/Shepherd mix, and she won't stop biting! She constantly lunges for our pants, the grass, the poop bag, our hands, basically everything. She has chew toys, but she seems to think humans make better chew toys! I'm pretty sure she got adopted once, and then was brought back, which is sad. I'm wondering if the biting was the issue. There's an elderly lady who won't even walk her because she's so grabby. Sunday she bit my mom's pants, and her teeth went through to the skin and made her bleed. She got her pretty good too. I'd like to teach Daisy it is not acceptable to bite humans, but I've never met a puppy like her. I've had two dogs, and neither of them bit at people this much when they were puppies. No other puppy who's come through the shelter has been so nippy. I'd like to help her learn, so that she can go to her forever home. Any tips?