This work by Zachau is intriguing. The bass line bears remarkable similarity to that in the 2nd movement of Mendelssohn's Organ Sonata No 6 (based upon another chorale - Vater Unser im Himmelriech). Since the Zachau work clearly precedes Mendelssohn's composition, one wonders if the former influenced the latter.
Registration involves principal choruses to 2-foot on all manuals coupled, with the addition of the soft 8-foot reed on the Recit for added colour and to help define the bass line.
This is a replacement upload due to poor audio quality of the first.