In natural and wastewaters frequently there are suspended and coloid dispesions that require cleaning by technological processes of coagulation and ultrafiltration. Electrokinetic properties of suspended and coloid particles, e.g. isoelectic points and electrokinetic (zeta) potential, are important for understanding of the mechanisms and prediction of the effectiveness of the technological procedure of sedimentation. Properties of the coloid (pigments) and rough (auxiliary pigments) suspensions and coloid (dyestaff, polymer molecules) and solid solutions (solvents) are important for analizing the wastewaters of graphic industry. In this work the effectiveness of the classic sedimentation procedure was investigated – coagulation of the wastewaters with the anorganic coagulant ferro iron (III) chloride and H3O+ ions in the printing color factory Chromos, Samobor. The results have shown that the Fe3+ ions are effective coagulants for neutralization of the negative charge of the pigments, auxiliary pigments (CaCO3) and binders (acrylic polymers), while H3O+ ions (pH=3) neutralized charges of the acrylic polimers, CaCO3, and, partly, pigments. Non-coagulated pigments, solvent molecules and non-polar polimer molecules have to be removed by adsorption on hydrophobic adsorbents, membranic processes or their combination (so called complex hybrid processes).