| Summary: | Aluminium sulphate (Al2SO4)3 or commonly known as alum has been used as a coagulation-flocculation agent by water treatment industries around the world, including Malaysia. Regardless of its effectiveness in purifying the raw water, it produces a large volume of alum sludge. In Malaysia, alum sludge is categorized as scheduled waste where it requires to be transported only to approved landfills and the costs could be high. Hence, reusing and recycling the alum sludge may be beneficial for water treatment industries in reducing the disposal cost. In this study, acidification method using nitric acid at a molarity of 0.5M – 2.0M is employed to recover a maximum percentage of aluminium from alum sludge. The findings showed that the difference in molarity of nitric acid is proportional to the recovery rate of aluminium up to 99% of the recovery. The performance of recovered coagulant in removing turbidity from raw water was evaluated at variations of dosage (0.5 – 12 mg/l) and pH (2 – 13). At an optimum dosage of 2 mg/l, the recovered coagulant efficiently removes the turbidity of raw water at 93.32% and achieved 99.47% at pH 7. Consequently, the use of recovered coagulant can promote a sustainable environmental approach to converting waterworks residuals into usable resources, particularly in water/wastewater treatment industries. ©2022 by authors, all rights reserved.
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