Use of Natural Coagulants in the Removal of Color and Turbidity from Laundry Wastewater

Laundry wastewater has a high amount of dirt from the washed items and chemical additives used in washing process. Aiming the primary treatment of this type of wastewater, three different natural coagulants (Tanfloc POP, Tanfloc SL, and Tanfloc SG) were evaluated in the removal of color and turbidity by the coagulation/flocculation/sedimentation process (C/F/S). The results showed that the time between 5 and 10 min was sufficient for the sedimentation of the flakes, with a time of 10 min being adopted for further studies. The statistical analysis and the cost of acquiring the coagulant were decisive in the selection of the best natural coagulant. The maximum values of color (88.7%) and turbidity (92.8%) removal efficiency occurred at a concentration of 120 mg L −1 (concentration determined by the Fischer LSD test) and the lowest cost (0.75$) obtained for the Tanfloc POP coagulant. The volume of sludge generated was higher in the treated effluent sample compared to the control sample, which proves the removal of total solids present in the effluent. The Tanfloc POP coagulant showed a high performance in removing color and turbidity from industrial laundry wastewater; it has been as a promising coagulant in the primary treatment of wastewater in this service sector.