[Effect of temperature on the Pb2+ biosorption with aerobic granules]

Experimental studies were conducted on the effect of temperature on the Pb2+ biosorption with aerobic granules seeding with floccular activated sludge. The results showed that the aerobic granules manly comprised the elements of C, H, N, O and P. According to the elemental compositions of the microbial granules, the corresponding empirical formula of the granules can be determined as C5.7 H10.9 O3.9 NS0.04. ESEM results showed many coccoid bacteria were visiable on the granule surface with porous structure. Both Freundlich and Langmuir isotherm equations could describe the biosorption process well (R2 > 0.914)under various temperature (20-40 degrees C). The maximum biosorption capacity (Q(max)) increased from 80.65 mg x g(-1) (20 degrees C) to 97.09 mg x g(-1) (40 degrees C). The values of thermodynamic parameters (deltaG < 0, deltaH > 0, deltaS > 0) indicated the biosorption process was spontaneous and endothermic in nature. Moreover, the Fourier transform infrared spectroscopy (FTIR) results demonstrated that such active groups as -OH, -COOH and P = O were involved in Pb2+ biosorption but nothing to do with nitrogen-containing groups.