Woranart Jonglertjunya and Tidathip Lertchutimakul

pp. 669 - 677

Abstract

This research is concerned with the adsorption of humic acid by activated sludge obtained from an alcoholic beverage
plant and Bacillus subtilis (ATCC 6633). The effects of experimental factors such as initial pH, agitation speed, and types of
adsorbent have been studied to compare adsorption capacity. The characterisation of activated sludge and Bacillus subtilis
adsorption were examined by investigating the adsorption isotherm and kinetics. The results showed that the type of adsorbent had a significant relationship with adsorption capacity. In case of Bacillus subtilis, a maximum value of adsorption
capacity of 11.44 mg humic acid /g biomass was observed based on the Langmuir adsorption isotherm and K value of 3.17x
10^-2 ((mg/g)(mg/l)ⁿ) from the Freundlich adsorption isotherm. The kinetic studies indicated that a pseudo-second-order
equation fitted the data remarkably well resulting in a rate constant (k₂) of about 0.019 g·mg^-1min^-1 for the adsorption onto
Bacillus subtilis.