Zjawiska fizyczno-chemiczne towarzyszące koagulacji zanieczyszczeń wód powierzchniowych solami glinu i żelaza

Alum coagulation and ferric coagulation involve direct reactions with humic substances, yielding effective destabilization and consequently a high efficiency of organic matter removal. But there are also a number of competitive reactions (associated with the hydrolysis of the coagulant), which produce positively charged complexes. The efficiency of organic matter removal via competitive reactions is much lower because of the indirect destabilization of colloids. The proportion of the two groups of reactions depends on the Ca/Mg ratio. The adverse effect of the competitive reactions can be eliminated or at least reduced by selective treatment with inert calcium salt (e.g. CaCl2) or magnesium salt (e.g. MgS04). Similar improvement can be achieved via selective application of two coagulants - alum and iron salt.