The CC0 license is intended to be a "Public Domain Dedication". In jurisdictions where the public domain is non-existent: it attempts to waive all rights in order to be as close to the public domain as possible. However, be wary of how you use CC0. In some jurisdictions, there is the concept of "Moral Rights", which includes attribution, which can not be revoked by the licensor. In those cases, attribution is required.
The CC-BY license is a general, permissive license, requiring only attribution. With CC-BY licensed content, you are able to modify, re-distribute and even make commercial usage of it.
If you want to take CC0 licensed content, you can re-license it under CC-BY. Therefore, to answer your question, they are compatible.