Properties Characterization Of Living Cell Immobilization Carrier And Study On Its Biodegradation Property Of Quinoline

Quinoline is a nitrogen-containing heterocyclic compound which is difficult to biodegrade in wastewater.In many enhanced processing techniques for refractory organic matter,living cell immobilization technology has been widely concerned by researchers at home and abroad due to its high density of bacteria,strong resistance to impact load,strong adaptability to temperature and pH,and simple operation of solid-liquid separation.In this study,living cells were immobilized by different immobilization methods.The microstructure,pore size and specific surface area of the immobilized carriers were characterized by SEM and BET.The mechanical strength,mass transfer performance,and the degradation performance of quinoline in wastewater were investigated.The results were as follows:(1)8%~10%polyvinyl alcohol(PVA)and 1%sodium alginate(SA)were mixed as the cell immobilization carrier,and the quinoline-degrading bacteria(Achromobacter sp.L-1)were immobilized by repeated freezing and thawing three times.The SEM and BET analyses show that the immobilized carrier prepared by this method has well-developed surface pore structure and internal pore structure.The specific surface area is 1.158 m~2/g and the average pore size is 222.94 nm.The mass transfer performance is 62%and the mechanical strength is higher than 98%.When the concentration of quinoline was less than 500 mg/L,the degradation rate of quinoline was stable at more than 90%within 16 h after immobilization of immobilized L-1bacteria,and it was still well tolerated to 800 mg/L quinoline.,and repeated degradation using 30 times quinoline(300 mg/L)degradation rate is greater than 80%.(2)The L-1 strains were immobilized by gel beads and granular activated carbon.The SEM analysis showed that both had obvious pore structure.The L-1 bacteria immobilized by gel beads could degrade more than 95%of 300 mg/L quinoline within16 h~18 h,and after 30 cycles,the carrier did not dissolve and the mechanical strength was 100%.However,the activated carbon immobilized L-1 bacteria can degrade 300mg/L quinoline within 24 hours,but the bacteria lost a lot and the degradation rate was less than 50%after repeated use.(3)Activated carbon fiber(ACF)was added to the mixed solution of PVA and SA to form an adsorption-encapsulation composite immobilized L-1 strain.SEM and BET analyzer tests showed that the ACF has a long needle-like shape and is uniformLy interwoven with the embedding material.The specific surface area of the carrier is 1.736m~2/g and the average pore diameter is 201.37 nm.The mass transfer performance is78%,and the mechanical strength is 100%.The composite immobilized L-1 strain can degrade more than 95%of quinolone(300 mg/L)within 14h~16h.It has higher tolerance to quinoline(900 mg/L quinoline can be degraded within 32 hours).The carrier is complete after 30 times repeated use,and it has a lower comprehensive cost.(4)Adsorption-encapsulation composite method was used to immobilize mixed degrading bacteria.Experiments showed that the immobilized mixed degrading bacteria had higher degradation rate when quinoline concentration was lower than 300 mg/L,but the degradability was lower than that of immobilized L-1 bacteria as the concentration increased.Immobilized mixed bacteria can remove more than 85%TOC in a mixture of quinoline and phenol at a concentration of 100~300 mg/L within 16 h,and the luminescent bacteria acute toxicity test on the 300 mg/L mixed matrix solution showed that the toxicity was significantly reduced after 16 h degradation.In summary,by comparing various types of immobilization methods,adsorption-embedded composite immobilization method has better quinoline degradation ability and superior carrier performance,which can be reused for a long time,and can be used for actual wastewater treatment.