QString Test = textEditDescricao->text();
textEditDescricao->setText(QString::fromUtf8(Test));
You shouldn't do this, except for that everything looks OK.

Does your application update records from "bairros" table? Maybe you should check whether data in the database is correctly encoded? Do you see correct characters if you start psql, issue "SET client_encoding TO '<encoding_used_by_your_system>';" and select something from that table?