Sequential process of coagulation/flocculation/sedimentation- adsorption - microfiltration for laundry effluent treatment

Abstract

Laundries use in their washing process various chemical inputs, which give to their effluents alkalinity, organic load, color, suspended solids and surfactants, and these effluents cause damage to aquatic ecosystems if discarded without treatment. Hence, the effluent from this type of activity requires adequate treatment. Therefore, the aim of this work was to treat the effluent from an industrial laundry by a sequential process of coagulation/flocculation/sedimentation-adsorption-microfiltration (C/F/S-ADS-MF) and evaluate the final treated water quality. In the C/F/S stage, the statistical analysis (ANOVA, p-value<0.05; Fisher’s test, p-value > 0.05) indicated that 140 mg L−1 was the best natural coagulant concentration. To surfactants adsorption by activated carbon, the contact time required to establish the system equilibrium was 10 h, and the kinetic model of pseudo-second-order best represented the experimental data. The MF presented a permeate flux of 60.51 L h−1 m−2. The water quality parameters were improved with sequential process application, resulting in global removal efficiency of 99.9% for color, 80% for chemical oxygen demand, 92.9% for surfactants and 99.4% for turbidity. Therefore, the proposed sequential process showed to be a promising technique for industrial laundry wastewater treatment.