DEWATERING OF ALUM SLUDGE USING FLOATABLE MEDIA REACTOR

Abstract

Conventional drinking water treatment plants passing several treatment processes. These processes include coagulation-flocculation, sedimentation, filtration and disinfection. The added dosage of coagulant aluminum sulfate (Alum) (Al2 (SO4)3. 18H2O) about 25 to 40 mg/l which reacts with water Alkalinity and produces a gelatinous precipitate (called flocs) which grow by gentle mixing of water (called flocculation) and then settle in the bottom of the sedimentation tank. These flocs remove most of colloidal and suspended particles from raw water. A pilot scale was fabricated from scheduled uPVC pipe. The reactor was filled with floatable media (polystyrene) working as filtration media with counter flow concept. The alum sludge was discharged in the pilot scale setup from the sludge holding tank in the WTP using submersible pump. The pilot scale filter was tested at different rate of filtration (ROF) ranged from 25 to 400 m3/m2/d. In addition, different media heights (100 – 800 mm) were investigated to study the efficiency of the sludge thickening. The filter washing rate (ROW) was tested to determine the optimum ROW that will clean the filter. ROW equal to one to four times the ROF were investigated. This thesis divided into four chapters:

Chapter (1); Introduction This chapter describes the different processes of the conventional drinking water treatment plant that involve a group of treatment