REMOVAL OF DYE FROM WATER BY COAGULATION USING ALUMINIUM SULFATE AND LIME

Abstract

Wastewaters from textile industries represent a source of water contamination, and
should be treateq in some way' so as to reduce the concentration of the polluting ayes, prioI' to
discharge of the wastewater to the receiving envirorunent. In this study the dye . removal capacity of
locally produced alum was investigated; The efficiency of the process wa~ investigated in series of batch
experiments using simulated textile dye solutions to assess the effects of various process parameters:
conlftct time, alum-lime weight ratio, coagulanl: dosage, dye's initial concentration. pH and reaction
kinetics of coagulation. The result of the study showed that an increase in both coagulant dosage and
dye initial concentration increases the percentage of dye removal. In all cases the percentage of dye
removal at optimized conditions is nearly or above 90%. Most of the reactions are completed in less
than 20 minutes. The highest percentage of the dye removal was observed at pH around neutrality for
all the dyes indicating that addition of lime is indispensable to maintain efficient floc formation. The
reaction ~etics 9f Indantrene Brown and Imperon Orange was observed to obey pseudo first order
kinetics, with rate constants kl = 0.055 min-i and k2 '" 0.114 min-1 for Indantrene Brown and Imperon
Orange, respectively. It was found that alum combined with lime is suitable material for removing dyes
from wastewaters.