EVALUATION OF A PHYSICOCHEMICAL POST-TREATMENT FOR REMOVAL OF TURBIDITY FROM TANNERY WASTEWATER

A physico-chemical post-treatment of coagulation-flocculation was carried out at laboratory scale, applying the jar test to tannery effluents from a biological treatment. Chemical coagulants (ferric chloride) and natural coagulants (seawater) were used with a fixed dose of 30 mL / L of Nalco brand polychloride aluminum flocculant (10 g / 1000 mL). The objective was to evaluate the behavior of these individually tested coagulants in turbidity removal efficiency. Posttreatment was performed in two stages, the first one corresponded to the selection of optimal pH. The pH 11 allowed the coagulants to act effectively. Subsequently, in the second stage, the ideal dose of each coagulant was determined. The optimal dose for ferric chloride was 10 mL / L, while for seawater the ideal dose was 20 mL / L, in both cases removing percentages close to 100% turbidity. In this second stage both coagulants were able to remove the turbidity to non-detectable levels. It was concluded that the application of a physicochemical post-treatment based on the coagulation-flocculation process allowed the generation of an effluent whose turbidity complies with that specified in the Venezuelan environmental regulations for a type water 1, subtype 1A.