A novel type of nitrate removal process was investigated in this study, which coupled nitrate reduction by zero-valent iron(ZVI) with anaerobic ammonia oxidation(AMAMMOX). The zero-valent iron dosage was 71 g·L-1. The inoculation volume of ANAMMOX granular sludge was 200 mg·L-1. The agitation rate and environment reaction temperature of the CSTR was set up to 150 r·min-1 and 33℃±0.5℃, respectively. The pH of influent was maintained at 7.0-8.0.The result indicated that ANAMMOX bacteria could survive in nitrate and ZVI supplied system under neutral condition. The reactor was set up quickly with the nitrogen removal rate of 0.12 kg·(m3·d)-1 on the first 5 days, and maintained over 0.1 kg·(m3·d)-1 nitrogen removal ability with the effluent nitrite and ammonia concentrations below 2.0 mg·L-1 and pH value higher than 8.0. The nitrogen loss was up to 89% under the condition of 30-40℃, pH 4-6.Too extreme pH and temperature conditions were not favorable for the coupling reactions.
Keywords: ANAMMOX; coupling; nitrate reduction; nitrogen gas; zero-valent iron.