Recent advancement in the application of hybrid coagulants in coagulation-flocculation of wastewater: A review

Hybrid coagulants have recently received attention in water and wastewater treatment technologies mainly due to their cost-efficiency and exceptional performance. As such, this study highlights the recent advanced appli-cations of hybrid coagulants in wastewater treatment. The materials used for hybrid coagulants, such as those hybridised in chemical bond, structurally-hybridised, and functionally-hybridised under certain combination techniques (e.g., organic/inorganic, organic/organic, inorganic/inorganic, organic/natural polymer, inorganic/ natural polymer, organic/biopolymer, & inorganic/biopolymer), were evaluated and compared based on their applications on different type of wastewaters, experimental conditions, and treatment efficiency. The perfor-mance of inorganic/inorganic hybrid coagulation demonstrated high removal of turbidity (98.5%), chemical oxygen demand (COD) (73.3%), heavy metals (99.2%), and colour (98%) -seemingly better than organic removal efficiency. The optimum operational conditions for inorganic/organic coagulants at varied pH levels (6-12) lowered the cost for chemicals used for pH adjustment in treating industrial wastewater. Referring to the review outcomes, hybrid coagulation applications are indeed efficient for treatment of highly concentrated in-dustrial wastewater, such as oily wastewater.