THE EFFECTS OF THE TERMINATION OF SLAKED LIME DOSAGE IN WASTEWATER PRECIPITATION PONDS
The stability of an accumulated lime sludge after termination of lime addition was investigated at the Funäsdalen wastewater pond system in Sweden. The lime addition was terminated for 53 h and then resumed. pH decreased from approximately 12.0 to a maximum of 7.0 at the inlet and 10.0 at the outlet end of the ponds. A local fall of the wastewater was shown to be important for the dissolution of alkali from the sludge. The soluble phosphorus content in the wastewater decreased by the dissolution of the sludge. The sludge was heterogenous with respect to colour. Only a minor fraction of the calcium added was necessary to form hydroxylapatite.