Abstract
Adsorption of linear alkylbenzene sulfonate (LAS) by activated sludge has been studied, and the following results are obtained;
(1) The adsorption of LAS attained equilibrium in 1 hour.
(2) No effect of temperature on the adsorption of LAS was observed.
(3) The adsorption of LAS took place according to Freundlich's isotherm.
(4) The adsorption of LAS homologues isomers depended on the structure of hydrophobic group of LAS. That is, the longer the alkyl chain length and the shorter the distance of phenyl group from the far end of alkyl chain, the adsorption of these surfactants became increasing. This tendency was consistent with the biodedgradability of LAS homologues/isomers.
(5) The minus charge of activated sludge decreased with lowering of pH, and its isoelectric point was observed at pH 3.0.
(6) Furthermore, the adsorption of LAS increased with decreasing of minus charge of activated sludge, and then became constant below isoelectric point.
From these results, it was concluded that the adsorption of LAS by activated sludge depended on the structure of hydrophobic group of LAS.
