Removal of H 2S in down-flow GAC biofiltration using sulfide oxidizing bacteria from concentrated latex wastewater

Abstract

A biofiltration system with sulfur oxidizing bacteria immobilized on granular activated carbon (GAC) as packing materials had a good potential when used to eliminate H 2S. The sulfur oxidizing bacteria were stimulated from concentrated latex wastewater with sulfur supplement under aerobic condition. Afterward, it was immobilized on GAC to test the performance of cell-immobilized GAC biofilter. In this study, the effect of inlet H 2S concentration, H 2S gas flow rate, air gas flow rate and long-term operation on the H 2S removal efficiency was investigated. In addition, the comparative performance of sulfide oxidizing bacterium immobilized on GAC (biofilter A) and GAC without cell immobilization (biofilter B) systems was studied. It was found that the efficiency of the H 2S removal was more than 98% even at high concentrations (200–4000 ppm) and the maximum elimination capacity was about 125 g H 2S/m 3of GAC/h in the biofilter A. However, the H 2S flow rate of 15–35 l/h into both biofilters had little influence on the efficiency of H 2S removal. Moreover, an air flow rate of 5.86 l/h gave complete removal of H 2S (100%) in biofilter A. During the long-term operation, the complete H 2S removal was achieved after 3-days operation in biofilter A and remained stable up to 60-days.