Performance of cross flow trickling filter for H₂S gas treatment

A grading cross bio-trickling filter was designed for H₂S removal. Mixed microorganisms domesticated from the former experiment were immobilized to start up the trickling filter. Removal performances during starting up period and different loadings were investigated. Results showed that the immobilization of the trickling filter was completed within 3 d. The removal efficiency was higher than 99% when the inlet concentration was in the range of 110 mg·m^-3 to 230 mg·m^-3 (EBRT 30 s). At low inlet loadings, the front part of the trickling filter played a major role in H₂S degradation, accounting for about 85%. Microbial diversity and population of the front part were superior to the tail one. At higher loadings, microbial diversity and population of the tail part increased significantly, from 4.5×10⁷ cells·g^-1 to 5.17×10⁸ cells·g^-1, and the elimination capacity was also improved, from 0.04 g·h^-1 to 0.67 g·h^-1. Rod-shaped bacteria were the dominant microorganisms on the surface of ceramics in the steady state as observed by SEM.The surfaces of ceramics were covered by a lot of microbial metabolites at high loadings. Analysis of the metabolites indicated that the majority of H₂S was oxidized to sulfur and only a small portion was converted to sulfate.