Cannot extract BLOB from the database

I am using wamp server and phpmyadmin and php for implementing my database application. I have stored BLOB files in the database. But I am not able to extract the blob file in the original format and allow the user download it in the original format. Can somebody please help me? The screenshotenter image description here of the format of the blob when I extract it from the database is attached. The code for extracting from the database is also attached. The code extracts everything properly except BLOBS. Please someone help me.

foreach($_POST['passport'] as $entry) 
{
    $sql = "SELECT $entry FROM passport WHERE UID = '$j'";
    $a = mysqli_query($conn,$sql);
    $b = mysqli_fetch_array($a);
    $c = $b[0];
    echo "<tr><td>{$entry}</td><td>$c</td></tr>";
}