Granular activated carbon as nucleus for formation of Anammox granules in an expanded granular-sludge-bed reactor

Granular activated carbon (GAC) was used in an Anammox process treating synthetic wastewater with the aim of evaluating its use as a growth nucleus to enhance granule formation. In an expanded granular-sludge-bed reactor, granules were formed demonstrating excellent retention characteristics with an average settling velocity of 200 m/h (5 cm/s) over a startup period of only 38 days. The time required for formation of Anammox granules under the experimental conditions in this study, was thus demonstrated to be much shorter than that of others. A genetic analysis of the organisms in the granular bed revealed an abundance of Paenisporosarcina uncultured bacterium similar to other known Anammox bacteria.