Using php to return GROUP_CONCAT('column x') values

Answer 1

Use an alias for the column.

GROUP_CONCAT( provision_id ) as pids
...
echo $content->pids

Answer 2

If you are fetching into objects, you should give your columns names that are legal class member identifiers in PHP (I'll link to the manual, although their description of valid variable names is horrible):

SELECT ... GROUP_CONCAT(provision_id) AS provisions