Role of phosphorus in activated sludge.
Monod's kinetic model was used to correlate the specific growth rate of mixed activated sludge with the limiting substrate of phosphorus for both batch and continuous-flow culture systems. In the batch reactor system, the specific growth rate varied from 0.092 to 0.617 h(-1) and the saturation constant changed from 25.5 to 117.5 when the COD: P ratio was controlled within the range of 10 to 788 and at the temperature 25+/- 0.5 degrees C. An inverse relationship between specific growth rate and cell yield was found. the maximum specific growth rate and the saturation constant obtained from this study were equal to 0.64 h(-1) and 0.378mg/L, respectively. In the completely mixed continuous-flow culture system, it was found that the substrate utilization, biological solids production, and sludge composition were markedly affected by the source of phosphorus available in the wastewater. The phosphorus-limited activated sludge is normally high in carbohydrate content and low in protein content. Also, sludge organisms growth under the severely restricted phosphorus condition usually possess a large capsule. These capsulated carbohydrate-like substances can be converted to cellular protein if the source of phosphorus is added. The values of cell yield in the continuous-flow activated sludge system are predictable by the use of kinetic constants that are generated from batch culture studies.
Department of Civil Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Y C
YC
Wu
M S
MS
Okrutny