| Air pollution of SO2 caused by coal burning is one of the hottest issues concerned by all over the world. In recent years, with the increasing discharge of SO2 . air pollution caused by SO2 has become the main factor which limits the development of national economy and society. Successful experiences abroad indicate that the removal SO2 from flue gas is an effective method to decrease the SO; pollution. The immobilized microbial biomass technology has been discussed in this thesis to treat SO2-contamined flue gas, which managed to hunt a new method to this issue.This project is a subproject financed by Nature Science Fund of Yunnan Province, which concludes the following attempts:1. To screen a type of bacteria which have the most strong degrading capability;2. To study and contrast three immobilized technologies in common use so as to determine the optimal conditions of the single operation;3. To improve single immobilized technology with combined processing, which can further improve mechanical strength and acid resistance of immobilized microbial biomass; to determine the most optimal operation conditions;4. To research the SO2 removal capacity of the biochemical reaction system. Domesticating and screening research of biomass indicated that the bacteriawith strong SO32- degradation capacity can be cultivated in the waste water, using induced domesticating method. The SO32- resistance of the bacteria is up to 1095g/m . with its degradation rate being up to 2400g/m3.h. Moreover, this type of bacteria can utilize SO2 directly, which establishes the basis of the biochemical reactor research treating low-fraction SO2 waste gas.Immobilized technology research proved that three technology in common use have their disadvantages: biosorption has a high bacteria activity and meets with low spatial resistance, but its immobilized biomass is prone to be washing out; the immobilized biomass of crosslinking technology is stable, but its biomass has a low activity and has no defending capacity without a carrier; encapsulating technology meets with high spatial resistance, but it is stable and economical, and itsimmobilized biomass has a high activity and a defending capacity. Calcium alginate encapsulation technology is determined to be the main method, with the target of relative activity, whose optimal operation conditions are as following: bacteria solution dosage 10mL. 5% sodium alginate solution. 4% calcium chloride solution, immobilized time 14h.Research results of combined immobilization technologies suggested that the biosorption-cncapsulating method can raise the acid resistance of immobilized spherules. but can't obviously improve their mechanical strength; the encapsulating-crosslinking method can improve the mechanical strength of immobilized spherules but decrease their acid resistance: the biosorption-encapsulat -ing-crosslinking method is the best combined immobilization method, which can not only raise the acid resistance but also improve the mechanical strength greatly The most optimal immobilization conditions of the biosorption-encapsulating -crosslinking method are as following: 10ml spawn solution and 0.3 gram activated carbon is encapsulated with 5% sodium alginate solution so as to get immobilized spherules, then the immobilized spherules are immerged in 4% calcium chloride solution for 14 hours and. henceforth, crosslinked in 0.06mol/L hexane diamine solution for some time.A series of experiments had been done to remove SO2 with the biochemical reaction system. Several factors had been studied such as solution sprinkling, gas retention time and gas original fraction. The research suggested that the removal efficiency of the system can be up to above 98% in the absence of sprinkling system, with the gas retention time 5s and original fraction of SO2 below 5g/m3. The biochemical reaction system was proved to have strong biosorption capacity to treat SO2-contamined gas. which can be up to 8.19mg/g. Additionally, the biosorption capacity of the system c... |
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