REMOVAL OF DYES FROM TEXTILE EFFLUENT BY ADSORPTION ONTO OVEN DRIED ALUM SLUDGE

Abstract

The present study deals with the removal of dyes from the effluent of the state company for cotton textile industries located at Al-Khadmya by using oven dried alum sludge (ODS) as adsorbent. Two different dyes; Direct black and solar brown are studied. Alum sludge was collected from Al-Qadisiya water treatment plant; it was heated in an oven at 105°C for 24 hours, then cooled at room temperature and crushed to produce particle sizes of 1.18-2.36 and 4-4.75 mm. Batch and fixed bed mode were used. In batch experiments the effect of oven dried alum sludge weight on adsorption process and equilibrium isotherm were studied by using 15-125 g/l of oven dried alum sludge for direct black and 15-175 g/l for solar brown, with constant initial dyes concentration of 10 mg/l and constant particle size of 4-4.75 mm. Batch kinetics experiments showed that equilibrium time was about 12-14 days. The three models Freundlich, Langmuir and Freundlich-Langmuir gave good fitting for the adsorption capacity. In the fixed bed isothermal adsorption column, the effect of initial dye concentration (Co), particle size, influent flow rate (Q) and bed depth (H) were studied. The results showed that the oven dried alum sludge was effective in adsorbing dyes with removal efficiency ranged between 90% to 92%.