Performance of Pumice Stone as a Packing in Fixed-bed Aerobic Bioreactor

Abstract

In this research, the performance of pumice stone as a fixed bed support in the biological treatment of the synthetic wastewater of sugar beet factory was evaluated. Pumice is a volcanic rock having high porosity and specific surface. and in comparison with other supports, pumice has a very low price. The experiments were done on an up-flow biofilm reactor, the effective volume of which was 14.2 L, with pumice fixed bed supports. After the starting period, the reactor was operated in steady-state mode, which lasted 222 days, at hydraulic retention time of 12, 16 and 24 hours and influent COD concentration of 750, 1500 and 2250 mg/L. During the operation, the contamination removal efficiencies from 89 to 97 percent were achieved in 9 experimental runs. The results demonstrate that in organic loading rate from 750 to 4500 gr.COD/m3/day in the mentioned status the reactor's efficiency is satisfactory. In addition, some kinetic prevalent models were tested with the experimental data. Results show that according to the regression coefficients, Grau second order kinetic model and modified Stover-Kincannon model are appropriate for predicting similar reactors situations and designing new reactors, and the related equations were derived