| Abstract |
| The recycled water with high NH3-N concentration, which was returned to activated sludge from anaerobic digester, was oxidized under the oxic condition and also were investigated on the behaviors of NO2--N and NO3--N in the biological nitrification process. The nitrification rate of NH3-N depends on alkalinity in water and the consumed alkalinity for nitrification of NH3-N was 6-8 mg CaCO3/mg NH3-N. In nitrification of recycled water conducted with no injection of activated sludge NO3--N not exist but NO2--N was detected to the high concentration of 140 mg/L. It was considered to why high alkalinity in recycled water was acclerated the growth of nitrosomonas but inhibit the growth of nitrobacter, oxidizing NO2--N to NO3--N. Therefore, to decrease NH3-N loading rate for aerobic basin of activated sludge process issued from recycle water of anaerobic digester, the optimal process for removal of NH3-N in recycle water was considered the anammox process using NO2- as electron acceptor. |
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| Key Words |
| Biological nitrification, anaerobic digester, recycled water, anammox |
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