Modeling effect of remaining nitrate on phosphorus removal in SBR.
Nitrate shock loading experiments were conducted in a bench scale SBR to investigate the effect of nitrate on phosphorus removal. After achieving satisfactory phosphorus removal under steady state operation, initial NO3-N concentration amounting to 10 and 20 mg/L was fed at the beginning of the cycle. It was observed that, 10 mg/L of NO3-N suppressed phosphorus release during the feed and mix phases. Organic consumption for denitrification lead to limited PHA storage by phosphorus removing bacteria, resulting in less PO4-P removal. For 20 mg/L, influent organic substrate was not sufficient even for complete denitrification, thus leading to the presence of higher NO3-N and PO4-P in effluent. To explain the dynamics of the nutrient removal system under the transient loading, a SBR model based on IAWQ ASM2 was implemented. After adjusting PHA contents, model simulations well predicted dynamic changes of nitrate and phosphate concentrations during a cycle. Based on the model simulations, competition of COD substrate among denitrification, fermentation and oxygen respiration were investigated by calculating their consumption rates during mixing phase. In addition, a nitrate disappearance model was proposed and implemented in conjunction with a settling model to predict remaining and effluent nitrate in a cycle of SBR. Furthermore, integrated model simulations highlighted the effect of remaining nitrate on phosphorus release considering different options of reactions in settling phase.
Kazmi
A A
AA
Department of Urban Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8656, Japan.
Fujita
M
M
Furumai
H
H
D019149:Bioreactors; D008962:Models, Theoretical; D009566:Nitrates / Q000302:isolation & purification*; D010758:Phosphorus / Q000302:isolation & purification*; D014865:Waste Disposal, Fluid / Q000379:methods*
D009566:Nitrates; D010758:Phosphorus