SQLAlchemy convert field using utf8

How do I get the equivalent SQLAlchemy statement for this SQL query?

select CONVERT(blobby USING utf8) as blobby from myTable where CONVERT(blobby USING utf8)="Hello";

Where blobby is a blob type field that has to be unblobbed to a string.

I tried this

DBSession.query(myTable).filter(myTable.blobby.encode(utf-8)="Hello").first()

But doesn't work. Gives out a queer error

AttributeError: Neither 'InstrumentedAttribute' object nor 'Comparator' object associated with myTable.blobby has an attribute 'encode'

Moreover, I tried inserting into the database as follows:

que=myTable(blobby=str(x.blobby))
DBSession.add(que)

This also returns an error that says

(ProgrammingError) You must not use 8-bit bytestrings unless you use a text_factory that can interpret 8-bit bytestrings (like text_factory = str). It is highly recommended that you instead just switch your application to Unicode strings.

This error goes away if I insert like

que=myTable(blobby=str(x))

But the inserted entries look like ('hello',),('hi',) and so on..

 EDIT:-

This is what I am trying to do :

I have a list of utf-8 strings. The sqlalchemy column which I am
trying to insert my string has the property "convert_unicode" set to
true. Now, I have to insert these strings into my database without
loss of data. I need to preserve my multilingual characters which
worked fine when I fetched them as utf-8 from my Mysql database.
Trouble here is inserting them into SQLite using SQLalchemy.

Please help. Thanks and Regards.