Comparison of adsorption performances of powdered activated sludge and powdered activated carbon for removal of turquoise blue dyestuff

Abstract

Effective treatment of dyestuff containing wastewaters require advanced treatment technologies such as adsorption for the removal of dyestuffs. Powdered activated carbon (PAC) has been the most widely used adsorbent for the removal of dyestuffs from wastewaters. As an alternative to PAC, powdered activated sludge (PAS) was used as adsorbent for dyestuff removal from synthetic wastewater in this study. The colour removal performance of PAS was compared with that of PAC under the same experimental conditions. Turquoise Blue-G was used as the dyestuff and the effects of adsorbent concentration on the rate and extent of colour removal were investigated for both adsorbents. The colour removal performance of PAS was comparable with that of PAC at high adsorbent concentrations above 4 g l −1, resulting in nearly 95% colour removal with 200 mg l −1 initial dyestuff concentration. The rates of dyestuff removal were comparable for both adsorbents when initial adsorbent concentration was larger then 4 g l −1. Maximum dyestuff removal rates obtained with 6 g l −1 adsorbent concentration were 85 and 80 mg l −1 h −1 for PAS and PAC, respectively. Three different isotherms were tested for correlation of the equilibrium adsorption data and the Langmuir isotherm was found to be the most suitable one. The maximum adsorption capacities of PAC and PAS were approximately 100 and 92 mg g −1, respectively.