Bio oxidation of Sulphur: Effect of Microbial Species on Oxidation Kinetics

Abstract

The use of elemental sulphur (S0) to alleviate widespread S deficiencies in agricultural soil is limited by the unpredictability of its oxidation to plant available sulphate. Because Sulphur oxidation is a biological process, it is strongly influenced by microbial activity including soil temperature, water potential, aeration & effective surface area of S exposed to microbial community. Thiobacillus thiooxidans ,a acidophilic chemoautotrophs known as potential sulphur oxidizer taken here as reference bacteria to study the growth & sulphur oxidizing ability along with the pure cultures of five isolates designated as S1,S2,S3,S4 & S5 . S1, S2, S3 are heterotrophic bacterial cultures isolated from garden compost soil while S4 & S5 from petrochemical ETP site. S1, S2 & S3 cultures studied for sulphur oxidizing potential by monitoring the pH reduction profile, growth pattern & sulphate concentration. The results of experiments & kinetic constant calculation for each showed first order reaction. The free, adsorbed & total cell growth measured as a function of time of contact between the cells & sulphur particles. The free cell concentration rapidly decreased with increasing contact time. However the total cell growth increase is little in all cases so it is difficult to calculate growth kinetics. Sulphate productivity calculated for all above listed isolates indicates the superiority of S-3 culture [6.51*10-4 (g/L/h)] & the order of sulphate productivity as S-3>S-2>S-1.