Effect of preozonation on organics coagulation removal from water

The objective of this research was to study the effect of preozonation on a subsequent coagulation process when treating polluted surface waters. The results show for raw water containing only phenol, ozonation gives rise to more polar compounds, which are capable of forming hydrogen bonding or complexing among themselves or with hydrolytic products of the coagulants, so the organics removal may be enhanced. However, for raw water containing only humic acid, the effect of preozonation is insignificant. Furthermore, for the organic and clay mineral coexistence system, the hydrolytic products of co‐agulants may react preferentially with the ozonated organics; and turbidity removal is retarded. So, the effect of preozonation on coagulation depends on several factors, such as the type of dissolved organics, the existence of suspended solids, and the type and dosage of coagulants used.