Effect of blending process on retention time for sludge thickening

The objective of this paper is to study the effect of blending process as a method for increasing the efficiency of the gravity thickener on its retention time. The problem is that in Egypt in many wastewater treatment plants, the gravity thickener efficiency is lower than expected, the solids outlet is lower than expected especially when the primary and secondary sludge mixed. In this paper, we study the effect of using dilution water (effluent water from Al Gabal Al Asfar wastewater treatment plant) on the retention time of the gravity thickener. The results explained that it is not suitable to increase the retention time in the gravity thickener when mixing the primary and secondary sludge and when adding the dilution water.