Natural coagulants replacing ferric chloride for wastewater slaughterhouses treatment

Abstract

This study purpose was to investigate the usage of two natural coagulants: Tanfloc SG® and chitosan, in order to replace the currently ferric chloride usage by the wastewater coagulation process from slaughterhouses subsequently initial treatment. Preliminary tests were accomplished to delimit the research groups of the operating parameters: pH and coagulant concentration, based on the wastewater COD diminution. Therefore, following these results, the tests were defined by a rotational central composite design (CCRD) with three central and four axial points, amounting eleven tests, demarcating the optimum operating parameters for each coagulant, which were, respectively, pH 7.0 and concentration of 200.0 mg.L-1 for Tanfloc SG®, pH 4.0 and concentration of 500.0 mg.L-1 for chitosan, and for ferric chloride, it was pH 4.5 and concentration of 100.0 mg.L-1. Tests were managed under optimal conditions and the results suggested that the Tanfloc SG® coagulant was expressively more efficient in the secondary wastewater treatment from slaughterhouse.