Enrichment of Anammox Biomass from Different Seeding Sludge: Process Strategy and Microbial Diversity

The current study aims to tackle one of the main obstacles in the application of anaerobic ammonium oxidation (Anammox) technology, i.e., the extreme slow growth of the Anammox bacteria. Three conventional sludge has been tested in sequencing batch reactor for Anammox enrichment, including conventional aerobic sludge, denitrification sludge, and anaerobic sludge. With a high selection stress and insufficient oxygen control, the reactor seeded with aerobic sludge reached 50–60% total nitrogen removal after 240 days whereas that seeded with anaerobic sludge failed to establish Anammox activity. Anammox process was successfully established in the reactor seeded with denitrification sludge with a total nitrogen removal of approximately 80% after 150 days under strict oxygen control (DO