Decolorization of wastewater by adsorption on activated carbon in a liquid solid fluidized bed

Abstract

The competency of liquid-solid fluidized bed of granular activated carbon as the adsorbent in removing color from wastewater was studied. The present study dealt with experimental study of a tertiary stage waste water treatment process, focusing on decolorization. Experiments were undertaken to obtain breakthrough curves and compare different operating conditions of the system. The parameters altered were velocity of the wastewater, particle diameter and initial concentration. A Reactive Black dye solution was passed through a defmite size of activated carbon bed at a constant flow rate and the exit solution was collected at definite time intervals. Concentration of the samples was analyzed by spectrophotometer (UV-1201, UV-VIS spectrophotometer) and the concentration against time was plotted to get the breakthrough curve. The effects of change in particle sizes of adsorbent (1.3- 1.15mm, 1-0.84 mm, 0.84-0.71 mm), colored water velocity (0.034 mis, 0.0254 mls and 0.0170 mls), initial dye concentrations (29.45ppm, 23ppm, 18.45 ppm) on dye removal were investigated. Equilibrium adsorption isotherms and breakthrough curves were generated and used to determine adsorption characteristics of the activated carbon as well as mass transfer coefficients of the fluidized bed. The results of these experiments showed that an increase in velocity and decrease in particle size increased the color removal leading to improved mass transfer. Besides, increasing the initial concentration reduced the active time of the activated carbon. Finally, experiment was carried out with industrial effluent and the color removal achieved was satisfactory.