THE RELATIONSHIP BETWEEN THE STRUCTURE OF ACTIVATED-SLUDGE FLOCS AND THE SORPTION OF HYDROPHOBIC POLLUTANTS

The relationships;between the structure of minimally perturbed activat ed sludge flocs and the sorption of organic contaminants were studied. Sorption,; settling velocity, size distributions, flee structure and EPS composition were all examined. The results show significant remova l of selected halogenated hydrocarbons and polycyclic aromatic hydroca rbons by biosorption to activated sludge flocs. However, statistically significant effects on the settling or size of the flocs caused by th is sorption were not observed. The addition of chromium (Cr(III)) meta l ions to the biomass caused observable changes in the flee structure and decreased ruthenium red binding to the acidic polysaccharides of t he floc matrix. At low concentrations (0.6 mg/l), chromium caused an i ncrease in the sorption of organic compounds to flees. suggesting that changes in the flee structure can be induced, which can have an impac t on the sorption of pollutants to the flocs. (C) 1998 IAWQ. Published by Elsevier Science Ltd.