LAUSR

Abstract Autotrophic denitrification and the simultaneous NH4+-N and total phosphate (TP) removal performance of elemental sulfur/lime (S/L) biofilter were investigated for the tertiary treatment of secondary effluent. Removed NO3−-N loading rate increased with the influent NO3−-N loading rate and complete denitrification was obtained at loading rates <0.298 kg/(m3·d). Half-order constants were 2.359, 3.314, 3.437, and 4.288 mgNO3−-N1/2/L1/2·h, respectively, for Empty Bed Residence Time (EBRT) of 2, 1, 0.75, and 0.5 h. Moreover, NH4+-N and TP removal performance was studied for the first time, and results indicated that NH4+-N and TP could be simultaneously removed in the S/L biofilter for tertiary denitrification. Approximately 0.081 mg/L NH4+-N was removed per mass of nitrate denitrified under condition where no nitrite was accumulated. About 0.103 mg/L TP could be removed under different EBRTs and pH was a limiting factor for phosphorus removal performance. NH4+-N and TP removal characteristics were re...