Abstract: Take the cation starches as the flocculant, adds PAC (polyaluminium) as the assistance flocculant, in factor under and so on consideration temperature, pH value influences, studies its effect on the printing waste water processing. This article matches the 7 mg PAC with the 90 mg cation amount of starch the 6 mg PAC to handle the 50 ml to printing waste water respectively with the 94 mg corn starch, its percent of decolorization and the turbidity elimination rate all may reach 100%. The result of the experiment showed that the match of that flocculant to the printing waste water processing effect is more ideal.

Key words: cation starch, flocculant, printing waste water