Anoxic ammonia removal using granulated nanoscale oxyhydroxides of Fe (GNOF) in a SBR

Abstract Microbial mediated anoxic ammonia removal in the presence of granulated nanoscale oxyhydroxides of Fe (GNOF) was investigated in a SBR, as a novel alternative to conventional nitrification and denitrification. Activated sludge flocs collected from a SBR treating sewage was used as seed biomass to develop the process. After confirming the feasibility of anoxic ammonia removal, SBR operations were carried out for 267 days in 9 phases by varying the initial NH 4 + -N concentrations from 100 to 500 mg/L and cycle time from 2 to 0.5 day. Effective anoxic ammonia removal was achieved in 0.5 day cycle time with the removal rates of NH 4 + -N and TN as 130 mg/L/d and 115 mg/L/d, respectively. Batch studies showed that the optimum COD/NH 4 + -N ratio for effective NH 4 + -N removal was less than or equal to 2. The kinetics of NH 4 + -N removal, confirmation studies for GNOF coupled nitrification-denitrification and Fe redox cycling involved in the process were also performed and discussed. The developed process is economical as there is no need for aeration and alkalinity.