Natural organic matter and cationic interaction effecting water treatment process- A review

One of the significant challenges faced by water treatment plants is the transformation of natural organic matter with reference to their quality and quantity owing to the changing climatic conditions. The natural organic matter consists of heterogeneous functionalized groups among which phenolic and carboxyl groups are the dominant groups that are pH-dependent and shows a stronger affinity towards the metals. Properties of natural organic matter and trace elements govern the binding kinetics influencing binding of cations to functionalized groups at lower pH; precisely, Ca2+ ions form strong bonds with carboxylic groups and Zn2+ ions bond with the amine groups. The water treatment process mechanisms like adsorption, coagulation, membrane filtration, and ion exchange efficiencies are strongly affected by the presence of natural organic matter with cations complex/cations and /or by the natural organic matter alone. The complexation among the natural organic matter and coagulants enhances the natural organic matter removal from the coagulation processes’; further, Ca2+ ions addition enhances the process positively. The current review illustrates detailed interactions between natural organic matter and cationic interactions in the environment, cations’ preference and competition for the functionalized groups, and the potential impacts of cations on natural organic matter in the treatment facilities.