What are the differences between flocculation and coagulation in water purification procedures? Can spontaneous flocculation totally remove all colloidal in water? Since hydrophobic interaction and hydrogen bond are possible interactions in flocculation, why is it considered a physical process? Which one is the most effective method to treat water?

Both flocculation and coagulation have been extensively studied and used in the process of treating water from different sources. One of the pointed out differences is that flocculation is a physical method while coagulation is chemical. Books and literature have it that they both clarifying agents, and colloids settle to the bottom of the container.