Regular articleRapid start-up of the anammox process by denitrifying granular sludge and the mechanism of the anammox electron transport chain

•The denitrifying granular sludge mixed with anammox bacteria was inoculated sludge.•The biomass ratio of denitrifying granular sludge and anammox bacteria was 50:1.•Starting the anammox process was shortened to 28 day.•The anammox electron transport chain's mechanism was explored by inhibitors.

This study investigated the rapid start-up of an anaerobic ammonium oxidation (anammox) reactor by inoculating denitrifying granular sludge mixed anammox bacteria. The mechanism of the anammox electron transport chain (AETC) was also studied using nine different inhibitors in batch tests. This is the first study that shortened the start-up anammox reactor time to 28 days. Nitrogen removal rates (NRRs) up to 0.72 kg/(m3 d) on day 28 were achieved. Each studied inhibitor had a different binding site in the AETC. The effect of each inhibitor was determined by comparing the total nitrogen removal efficiency between the presence of an inhibitor and an appropriate control. The results confirmed that each inhibitor had various inhibition degrees that distinctly affected the AETC. Finally, the AETC mechanism was explored in detail. These findings are important for developing fast start-up processes for anammox reactors.

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