Application of Immobilized Bacteria in Biodegradation of Oily Wastewater

The dynamic adsorbing capacity of petroleum hydrocarbon degradation bacterium (W-2) on active carbon was studied at 25 ℃ by measuring the biomass of W-2 before and after adsorption. The effects of different immobilization methods,pH of cross linker and the biomass of W-2 on microbial beads (MB) physical appearance and biodegradation were examined. The experimental results showed that the direct immobilization was better than immobilization after adsorption and the optimal pH of cross linker was 5-6,the volume ratio of immobilized bacterial to gels was 1∶5. Meanwhile,the speed of immobilized W-2 reactivation was accelerated by adding inorganic salt into MB,and the surface texture of MB before and after biodegradation was observed from SEM. The influence of pH and salinity to MB biodegradation was investigated in the mineral salt media(MSM)containing 0.3% standard oil. The results showed that the adaptable range of pH was 7-8,that of salinity was about 3% for free W-2,and the adaptable range of pH was 6-9,that of salinity was 2%-5% for immobilized W-2,which were more tolerant than free;the biodegradation rate of free W-2 reached about 40% and that of immobilized W-2 reached above 70%,which increased more than 30%.