UTILIZATION OF DRINKING WATER TREATMENT SLUDGE TO PRODUCE ALUMINUM SULFATE

In Egypt, the water treatment industry consumes about 365,000 tons of aluminum sulfate as coagulant and produces more than 100 million tons of semidried sludge per year. The common disposal system of alum sludge in Egypt involves discharging it into natural water bodies, which poses risks due to the toxic nature of aluminum species to aquatic life, strict environmental regulations, and high costs of chemicals used in the treatment process. The objective of this study was to evaluate the recovery and subsequent reuse of aluminum metal from sludge obtained from the El-Shiekh Zayd water treatment plant through an acidification method aimed at producing aluminum sulfate coagulant. The study involved the characterization of sludge from drying beds, utilizing sulfuric acid as the acidic leaching medium, and testing the effects of variables including acid concentration, sludge weight, mixing speed, temperature, and leaching time. The results demonstrated that the maximum recovery of aluminum sulfate reached 94.2% under optimized conditions of 1.5 N acid concentration, 5 g sludge weight, 60 rpm mixing speed, 60°C temperature, and 40 minutes leaching time. This research presents an effective method for aluminum recovery that could contribute to sustainable practices in water treatment industries.