Immobilization Of Microorganisms On Cellulose Based Composite Microspheres And Their Applications

With the rapid development of economy,the problem of water pollution is becoming more and more serious.Phenol compounds which exists in coal chemical,petrochemical and pharmaceutical industry have a highly toxicity and make a great damage,especially.The low cost,high efficient and environmentally friendly water treatment technology is an urgent need in order to solve the current resources and environmental problems to our society.Green biocatalytic technology is based on renewable biomass resources as raw materials,microorganisms as the biocatalyst.In this thesis,cellulose-chitosan embedded microorganisms and cellulose-dopamine cross-linked microorganisms were synthesized by using cellulose as matrix material,then were studied for their capabilities on degrading phenol,2-naphthol and phenolic compounds from industrial coking water.Immobilized microorganisms CE-CS-E3 were prepared through a simple dripping method from cellulose and chitosan with the mass ratio of 1:1 and bacterial concentration 16%(v/v).The microspheres exhibited good spherical shape.When initial phenol concentration was 100 mg/L,the degradation rate of phenol with CE-CS-E3 was 97.3%,under the same condition with the free microorganisms,the degradation rate of phenol was only 76%.The effects of tempreture and pH on the degradation were studied.The results showed that the suitable temperature range of degrading was 20?40?,and the suitable pH range was 5.0?10.0.Treatment of phenol simulated water with 800 mg/L using CE-CS-E3 for 96 h,the degradation rate of phenol was 86.4%.The immobilized microorganisms CE-CS-E3 had better salt-tolerance property,saline wasterwater with phenol at 100 mg/L and NaCl at 40 g/L was treated for 96 h,84.8%degradation of phenol was achieved.CE-CS-E3 still worked after 21 cycling runs(7 h for each cycle),resulting in the degradation rate of phenol being more than 95%.Cellulose beads with uniform particle size and good mechanical strength were prepared through a dripping method.The resultant microspheres exhibited good spherical shape and maintained good mechanical strength.Cellulose beads was coated with dopamine to create a matrix for microorganisms immobilization.The optimum immobilization conditions of microbes were investigated.CE@PD-E were prepared crosslinking the microorganism for 24 h in 5 g/L dopamine solution,the degradation rate of 2-naphthol was 94.4%with CE@PD-E.The degradation rate of 35 mg/L 2-naphthol was 94.4%at 30? for 144 h,while the analogy experiment,the degradation rate of phenol with the free microorganisms was only 71.1%.The effects of temperature and pH on the degradation performance of immobilized microorganisms were investigated.The results showed that the degradation rate of 2-naphthol was the highest at 30? and pH 7.0.As compared with the free microorganisms,the immobilized microorganisms showed higher tolerance to changed in solution pH and temperature.The coking water from Ningxia Ningdong coal chemical industry base was treated with the immobilized microorganisms CE-CS-E3 to investigate the degradation activity.After 24 h,the phenol,o-cresol,m-cresol,p-cresol,3,5-dimethyl phenol and resorcinol,5-methyl resorcinol and 4-methylcatechol in the coking water could be completely degraded,meanwhile,the ammonia nitrogen concentration decreased from 149.3 mg/L to 87.4 mg/L,chemical oxygen demand decreased from 152.7 mg/L to 65.3 mg/L,biochemical oxygen demand total organic carbon and metal ions decreased dramatically.After the immobilized microorganisms were used 8 times,the degradation rate of total phenols was 84%,which indicated that immobilized microorganisms CE-CS-E3 were efficient for treating the coking water.The experimental results here provided the primary basis for the industrial waste water treatment with the immobilized microorganisms.