So I decided to test the NoSql Cassandra database. But to install was a non-trivial proccess on Ubuntu 16 release.
After some googling I found this link inside the Download area of the oficial Cassandra site. And then it works!
It was necessary to change the first key number for the one that is showing on the error after the apt-get update. I skipped the add of the other two keys and it works.
Hope this can help…