Treatment of ink-containing wastewater by coagulation/flocculation using biopolymers

A coagulation/flocculation process using a selection of biopolymers (chitosan and tannin) was used to treat an ink-containingeffluent generated in the processing of packaging. The efficiency of the process was investigated in terms of the influenceof pH, coagulant and flocculant concentrations, as well as chitosan characteristics (especially the molecular weight). Theprocess was particularly efficient under acidic solutions: the amount of coagulant and flocculant to be used were significantlyreduced by limiting the pH to 5. Optimum conditions for colour abatement (measured at 528 nm) were obtained at pH 5 usingthe most viscous chitosan (highest molecular weight) at a concentration close to 20 mg·ℓ-1 and a concentration of tannin closeto 70-100 mg·ℓ-1.