The role of coagulation in water treatment

• Coagulation plays primary and important roles in water and wastewater treatment.
• Researches are needed for novel coagulants, hybrid processes and control schemes.
• Study of floc properties is essential to enhance the coagulation efficiency.
• The performance of coagulation is the major factor in improving water treatment efficiency.

Water industries globally consider coagulation/flocculation is one of the major treatment units used to improve overall treatment efficiency and cost effectiveness for water and wastewater treatment. And then fundamental and applied studies have never been ceased although the modern coagulation has been applied for water treatment since the early 1900s. This review paper then outlines recent development of novel composite coagulants and hybrid processes combining the coagulation with other treatment units, explores the properties of flocculation flocs, and introduces practical schemes for the coagulant dose control. Possible future work in the area is suggested.