Abstract
A sequencing batch reactor (SBR) seeded with methanogenic granular sludge was started up to enrich Anammox (Anaerobic Ammonium Oxidation) bacteria and to investigate the feasibility of granulation of Anammox biomass. Research results showed that hydraulic retention time (HRT) was an important factor to enrich Anammox bacteria. When the HRT was controlled at 30 days during the initial cultivation, the SBR reactor presented Anammox activity at t = 58 days. Simultaneously, the methanogenic granular sludge changed gradually from dust black to brown colour and its diameter became smaller. At t = 90 days, the Anammox activity was further improved. NH ^sub 4^ ^sup +^ -N and NO ^sub 2^ ^sup -^ N were removed simultaneously with higher speed and the maximum removal rates reached 14.6 g NH ^sub 4^ ^sup +^ -N /(m^sup 3^ ^sub reactor^·day) and 6.67 g NO ^sub 2^ ^sup -^ -N /(m^sup 3^ ^sub reactor^·day), respectively. Between t = 110 days and t = 161 days, the nitrogen load was increased to a HRT of 5 days (70 mg/l NH ^sub 4^ ^sup +^ and 70 mg/l NO^sub 2^), the removal rates of ammonium and nitrite were 60.6% and 62.5% respectively. The sludge changed to red and formed Anammox granulation with high nitrogen removal activity.[PUBLICATION ABSTRACT]