type "e" does not exist , Redshift through Postgresql connector in php codeigniter

i'm using Redshift through Postgresql connector i got the following error while querying in php codeigniter 3.x, php version 7.0 the model is as follows

$subQuery = "select max(button_history_id) as button_history_id  from button_history
        where site_id =".$site_id." group by button_history_id ";

        $this->another->select('cms_group_id');
        $this->another->from('button_history');
        $this->another->where('button_history_id IN ('.$subQuery.")");
        $this->another->where('cms_group_id !=', '');
        $queryGrp = $this->another->get();
        $grpIds = array();
        foreach($queryGrp->result_array() as $grps){
            if($grps['cms_group_id'])
            $grpIds = array_merge($grpIds,explode(',', $grps['cms_group_id']));
        }
        if($grpIds){
            $grpIds = array_unique($grpIds);
            $this->another->select('content_history_id, (content_id),content_name,content_type');
            $this->another->from('content_history');
            $this->another->where_in('content_id',$grpIds);
            $this->another->group_by('content_history_id,content_id,content_name,content_type');
            $this->another->order_by('content_id ,content_history_id',"desc");
            $queryG = $this->another->get();
            $result1 = $queryG->result_array();
        }

but an unwanted E' is appending before the values as follows

ERROR: type "e" does not exist

SELECT "content_history_id", (content_id), "content_name", "content_type" FROM "content_history" WHERE "content_id" IN( E'358', E'357', E'359', E'361', E'408', E'398', E'362', E'366', E'363') GROUP BY "content_history_id", "content_id", "content_name", "content_type" ORDER BY "content_id" DESC, "content_history_id" DESC

this E'358' "E" is causing all the trouble , could anyone has any suggestions please respond. i'm new to this, and hv no idea what is the reson, i have added th info below.

php version :7.0 codeigniter :3.x OS: Centos 6.9

This E is for escaping character in PostgreSQL. See here.

Try to adding a third parameter to where_in, which avoid escaping.

$this->another->where_in('content_id',$grpIds, false);