$check_arr = Array('action,adventure,triller,scifiction','action,drama,adventure','action,adventure,triller,scifiction');
$new_arr = Array();

foreach($check_arr as $val){
	$genres = explode(',', $val);
	foreach($genres as $ganre)
		if(!array_search($ganre, $new_arr))
			$new_arr[] = $ganre;
}

	echo '<pre>';
	print_r($new_arr);
	echo '</pre>';