We used a biochemical reactor ...

We used a biochemical reactor (BCR) to reduce hex chrome to tri-chrome and precipitate it as Cr(OH)3.  See the abstract attached; we didn't submit a manuscript for this paper.  The BCR was not "powered" by detrose per se but the organic substrate we used probably produced similar compounds to create a reducing environment.  To learn more about BCRs, see http://itrcweb.org/bcr-1/.