The adsorption and biodegradation mechanisms overlap in the
biological activated carbon bed, and it is difficult to recognize the
predominant mechanism in removing contaminants [33]. Through
model simulation, the ratios of H2S removal by the adsorption and
biodegradation in the biofiltration operation could be obtained,
respectively (Fig. 3). The simulation results suggest that the ratios
of H2S removal by the adsorption decreased gradually with operation
time in the two columns. The adsorption ratios in Column
A decreased much more quickly than those in Column B for the
first 20 days. It might be inferred that the removal of H2S could be
attributed to the adsorption mechanism much less in Column A.