الفهرس 
IntrodutctionOnly 14 pages are availabe for public view
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Abstract
Although surface water treatment presents a good solution for pollutants in rivers and freshwater lakes, the purification process (coagulation / flocculation) presents a great threat to the aquatic environment through generation of large volume of waste or residue, known as water treatment sludge (WTS). As produced sludge contains high concentration of precipitated aluminum hydroxide that can pose severe environmental issues. Therefore, this study investigated the potential to recover aluminum coagulant from sludge using acid leaching process as a green solution for waste handling and cost reduction. However, there are some factors that affect efficiency in recovering aluminum, such as mixing time during acidification, pH, and sludge characteristic. WTS produced with the optimum alum dose of 30 ml/L at a petrochemical company water treatment plant in Alexandria was characterized, then acidified to bring forth a product known as recovered coagulant (RC), results of the parametric investigation reveal that the mixing time of 30 minutes, sulfuric acid dosing are the optimum conditions for alum recovery. The optimum pH level is 2 as indicated by maximum aluminum releasing, maximum reduction of sludge volume, and reasonable dosages of added sulfuric acid. The performance of RC is evaluated for its efficiency in removing the colloidal suspensions from intake water and compared to fresh coagulant (FC) performance, the result showed that RC has the potential to substitute the conventional FC partially or completely in the water treatment process, although some substances will be enriched during recycle, they have little effect on the quality of treated water.