Decolourization of the reconstituted textile effluent by different process treatments: Enzymatic catalysis, coagulation/flocculation and nanofiltration processes

摘要

The objective of the present paper is to examine the decolourization efficiency of textile effluent using different processes: coagulation/flocculation, enzymatic catalysis by commercial laccase and nanofiltration. A series of experiments are conducted on laboratory-prepared wastewaters combining chemically two reactive dyes (Blue Bezaktiv S-GLD 150 and Black Novacron R), auxiliaries and chemicals. To optimise coagulation/ flocculation and enzymatic treatment, response surface methodology is applied. Coagulation/flocculation leads to a maximum percent of colour removal of about 93% at 593 nm and 94% at 620 nm. Whereas, applied commercial laccase catalysis reduces colour by up to 99%. Nevertheless, these two processes have not the same behaviour on chemical oxygen demand (COD) and salinity removal since the obtained results show that applied coagulation/flocculation permits a partial removal of COD without effect on salinity. However, laccase treatment has no effect on COD and on salinity retention. The application of the nanofiltration shows excellent performances in term of decolourization (superior to 99%). In the same time, a partial retention of COD and salinity respectively of about 56% and 35% is obtained. Thus, nanofiltration seems to be an efficient process in colour removal of textile wastewater. The obtained permeate can be reused in the dyeing process in the textile industry.