REMOVAL OF HYDROGEN-SULFIDE BY IMMOBILIZED THIOBACILLUS SP STRAIN CH11 IN A BIOFILTER

An autotropic Thiobacillus sp. CH11 was isolated from piggery wastewat er containing hydrogen sulphide. The removal characteristics of hydrog en sulphide by Thiobacillus sp. CH11 were examined in the continuous s ystem. The hydrogen sulphide removal capacity was elevated by the BDST (Bed Depth Service Time) method (physical adsorption) and an immobili zed cell biofilter (biological conversion). The optimum pH to remove h ydrogen sulphide ranged from 6 to 8. The average specific uptake rate of hydrogen sulphide was as 1.02 x 10(-13) mol-S cell(-1) h(-1) in con tinuous systems. The maximum removal rate and saturation constant for hydrogen sulphide were calculated to be V-m = 30.1 mmol-S day(-1) (kg- dry bead)(-1) and K-s = 1.28 mu mol dm(-3), respectively. A criterion to design a scale-up biofilter was also studied. The maximum inlet loa ding in the linear region (95% removal) was 47 mmol-S day(-1) (kg-dry bead)(-1). Additionally, the biofilter exhibited high efficiency (>98. 5%) in the removal of hydrogen sulphide at both low (<0.026 mg dm(-3)) and high (0.078 mg dm(-3)) concentrations. The results suggested that the Thiobacillus sp. CH11 immobilized with Ca-alginate is a potential method for the removal of hydrogen sulphide.