From Waste to Value: Recovery, Optimization, and Reuse of Magnesium Hydroxide from Zero Liquid Discharge Wastewater for Sustainable Industrial Applications

Zero Liquid Discharge (ZLD) systems are increasingly adopted to minimise industrial wastewater discharge; however, they generate concentrated brine streams rich in dissolved minerals. This study focuses on the recovery of magnesium hydroxide from ZLD wastewater using a controlled precipitation method and optimisation of key process parameters. The influence of pH (9–12), temperature (25–60°C), and reaction time (30–120 min) on recovery efficiency was systematically evaluated. Maximum recovery efficiency of approximately 91% was achieved at pH 11, 45°C, and 90 minutes reaction time. The recovered magnesium hydroxide exhibited satisfactory purity and demonstrated effective performance in neutralisation and contaminant removal tests. These findings are consistent with earlier studies on magnesium recovery from brine systems (Almousa et al., 2024; Yong et al., 2024).