Humus coagulation

Humic substances occurring in natural waters in the form of stable negatively charged sols exhibit shielding aetion with respect to colloidal solutions of Si02, Fe(OH)j and Al(OH)3 (Kul skiy, 1960). Colloids shielded by humus do not coagulate and, remaining in the state of sols, can be transported by the waters of rivers, seas, and oceans (Kuznetsov, 1964) for considerable distances, and the Schultz-Hardy rule becomes inapplieable to shielded colloids. 

Adsorption complexes — these are formed by a reaction of humic acids and their salts with the surface of mineral particles, thus yielding complex microaggregates of different degrees of dispersion. They are most frequently formed by coagulation, involving precipitation of humus substances on the surface of clay minerals by means of exchangeable cations ... 

This can be colored, as turbid surface water may contain humus as well as iron and manganese, either in the oxidized form or bound to organic matter. Water of this type is treated by aeration + coagulation + addition of alkali + clarification + sand filtration. The removal of color and organic compounds usually requires a method based on chemical precipitation. Some reduction in organic matter content, of course, can be achieved by simple filtration. The removal of iron and manganese, on the other hand, usually requires ... 

The coloring of natural water varying from pale yellow to brown is due to the presence of humus substances. Their decolorization is carried out by adsorption on coagulated Al(OH)j or Fe(OH)j. The increasing demand for fresh water requires the use of more colored water, which however is pre-chlorinated, and then subject to adsorption up to their complete decolorization. 

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