<?php
$arr=array(
array("title"=>"viens", "project_id"=>6),
array("title"=>"divi", "project_id"=>8),
array("title"=>"tris", "project_id"=>3),
array("title"=>"cetri", "project_id"=>4),
array("title"=>"pieci", "project_id"=>5)
);
$arr2=array();
foreach($arr as $val) $arr2[$val['title']]=$val;
foreach($arr2 as $key=>$val){
echo $key." ".$val['project_id']."\n";
}