Biosorption of nitrophenols on anaerobic granular sludge

The sorption and desorption of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) on live anaerobic granular sludge was studied at five different sorbate (nitrophenols) concentrations between 10 x 10(3) - 90 x 10(3) microg l(-1). Experiments were conducted at room temperature (29 +/- 2 degrees C) and at an initial pH of 7.5. The maximum uptake capacity of live anaerobic granular sludge was found to b e 1,427, 1,511 and 1,865 microg g(-1) VSS for 2-NP, 4-NP and 2,4-DNP, respectively. The equilibrium data of three nitrophenols obeyed both Freundlich and linear isotherm models. Sorption was observed to be partially reversible. About 20-89%, 36-90% and 29-80% desorption was observed for 10 x 10(3) - 90 x 10(3) microg l(-1) sorbate concentrations of 2-NP, 4-NP and 2,4-DNP, respectively.