The Optimization Of Efficient Desulfurization Bacteria Degradation Conditions And Study Of Immobilization

This paper used dibenzothiophene as the model compound, obtained four desulfurization bacteria from Qingdao Petrochemical aeration tank sludge, Qingdao Petrochemica settling tank sludge, Qilu Petrochemical sulfur sludge, Finally selects an efficient desulfurization strain after the detetermination of desulfurization effect and Strains’ s carbon source utilization, named QLSH-2. It was identified as Rhodococcus bacteria. The sulfur source adaptive experimental results show that QLSH-2 have the ability to Degradate thiophene, propyl mercaptan, dibenzothiophene. Single factor experiment was carried out on bacteria, and significant factor screening experiments was made based on this. The results show: pH, temperature, the amount of carbon added was the key factors influencing the desulfurization efficiency. Response surface optimization experiments show that, when temperature was 27.4, the amount of carbon added was 11.6g/L, pH was 7.4, substrate concentration was 70mg/L, carbon source was glycerol, inoculum was 4%, rotation speed was 160 rpm, theoretical maximum degradation rate could reach 79.2%, the actual degradation rate of 78.0%. The interaction between the three key factors was significantly, the influence degree was temperature> pH> carbon amount. Volcanic particles after treatment was slected as the optimal immobilization carrier material from Volcanic particles, Diatomite, Na-Y zeolite. Using adsorption method to Preparated immobilized bacteria desulfurization. Single factor experiment was carried out on immobilized bacteria, and significant factor screening experiments was made based on this. The results show that temperature, Shaker speed and carbon amount was the key factors influencing the desulfurization efficiency. Response surface optimization experiments show that, when temperature was 25, shaking speed was 163 rpm, the amount of carbon added to was 11.3g/L, the amount of immobilized bacteria added to was 12 mL, substrate concentration was 80mg/L, pH was 7, theoretical maximum degradation rate could reach 81.6%, the actual degradation rate of 80.1%. The interaction between the three key factors was significantly, and the influence degree was temperature> Shaker speed>carbon amount. With the oil system simulated by dissolving dibenzothiophene in petroleum ether, the desulfurization experiment shows that, degradation ratio of dibenzothiophene of free bacteria and immobilized bacteria are 33.31% and 38.25% in the condition of volume ratio of oil and water is 1:9, inoculum of free bacteria is 6%, inoculum of immobilized bacteria is 14 mL and degradation time is 3 days. All of above shows that the effect of immobilized bacteria is better than free bacteria.