AJAX button on table rows to delete rows
I found the answer using drupal_render(). The buttons are now generated in each row, havin their own ids, so that I can read the triggering element in the callback function.
Now I only have the problem whe I click one of the buttons, the complete form is submitted. There seems to be no ajax callback. I will search further an will the edit the answer...

  foreach (aPersons as $key =&gt; $value) {
    $form_button['button'] = array(
      '#id' =&gt; 'del_'.$key,
      '#type' =&gt; 'button',
      '#value' =&gt; 'Delete',
      '#ajax' =&gt; array(
        'callback' =&gt; 'delete_person_ajax_callback',
      )
    );
    $deleteButton = drupal_render($form_button['button']);
    $row = array($value['dname'],$deleteButton);
    $aPersonsTable[]=$row;
  }