| This article,the microflora obtained from domestication in the activated sludge of the coking wastewater plant was taken as the research object,and a group of microbial flora that can efficiently degrade thiosulfate was obtained by comparing the degradation effect of the microflora and the single bacteria in the separation and screening process.The influence of external factors（cultivation temperature,pH,dissolved oxygen,carbon and nitrogen sources,etc.）on the degradation of thiosulfate by bacteria was explored,and the response surface of the factors with greater influence（temperature,pH,bacterial solution inoculum）was carried out.Optimized and explored the most suitable degradation conditions for the flora.By examining the broad spectrum of substrates of the microflora,the degradation effects of different pollutants（phenol,quinoline,naphthalene）under the action of the microflora were explored;The rate change and its overall dynamic law during the degradation of thiosulfate with different initial concentrations were explored,and the kinetics of the degradation was analyzed;The bacterial community diversity and community changes before and after microflora domestication were analyzed by high-throughput sequencing technology,and the reasons for the differences were explored;In addition,the bio-enhanced degradation effect of microflora in the coking wastewater industrial system was also explored,and the difference between the bio-enhancement of microflora and the degradation effect of original sludge was analyzed and compared.In addition,in order to reduce the loss of compound bacteria in industrial applications such as coking wastewater,Using microbial immobilization techniques,the immobilization effect,continuous usability and degradation of different carriers（vermiculite,diatomaceous earth;agar,alginate;polyvinyl alcohol,polystyrene;gel pellets,activated carbon gel pellets）on the microflora were initially investigated.The comparison of the degradation effect of the immobilized bacterial agent and the microflora over time was further explored,and the stress resistance performance of the immobilized bacterial agent was discussed;By comparing and observing the SEM morphology characteristics of the microflora before and after immobilization,the degradation effects of the microflora and the immobilized bacteria agent and the differences caused by the surrounding environment were analyzed.The main research results are as follows:（1）The comparison of the degradation effect of the microflora and the single bacteria showed that:when the concentration of thiosulfate was 3000 mg/L,the degradation rate of the microflora was 78.4%at 24 h,and the degradation rate of the mixed bacteria（the mixture of strains 2,5,and 6）was 53.4%.When the degradation is complete,the time used by the microflora is 12 h shorter than that of the mixed bacteria;At 36 h,the degradation rate of thiosulfate by microflora was as high as100%,and the degradation rate of single bacteria was up to 65.8%.It can be seen that the degradation effect of microflora was much higher than that of single bacteria and mixed bacteria.The effect of the microflora greatly enhanced the degradation rate of thiosulfate.（2）The results of the study on the degradation conditions of the thiosulfate microflora showed that:under the conditions that the nitrogen source was ammonium chloride,pH 6.0,temperature was 30℃,rotation speed was 180 r/min,and the bacterial solution inoculum size was 10%,the bacterial The group has the best degradation effect on thiosulfate.When the thiosulfate concentration was 6000 mg/L,the degradation rate was as high as 100%after culturing for 48 h;and the microflora had a strong tolerance to high concentrations of thiosulfate,and when the thiosulfate concentration at 12000 mg/L,the degradation rate was still higher than 60%at 48 h.In addition,the microflora has a broad spectrum of substrates and can degrade different pollutants（phenol,naphthalene,quinoline,etc.）,when the substrate concentration is 1000 mg/L,the degradation rate after 48 hours of culture respectively reached 100%,76.6%,45.8%,it can be seen that the microflora also has strong degradation performance when removing other pollutants.The results of response surface optimization experiments and degradation kinetics showed that the degradation rate of thiosulfate reached the maximum value of86.51%when the temperature,pH and inoculum amount were theoretically 31.24℃,6.16 and 10.25%,respectively.At the same time,the optimized degradation rate was verified to increase by 23.4%;The kinetic equation showed that the optimal decolorization rate and optimal thiosulfate concentration of the microflora for the degradation of thiosulfate were 0.137945 g g-1h-1,10.09243 g/L.（3）High-throughput sequencing results showed that after microbial domestication,at the phylum classification level,Proteobacteria changed most significantly,increasing from 61.5%in the environment to 91.4%after domestication.The biological community also mainly includes:Bacteroidetes（6.5%）,Firmicutes（1.5%）,Acidobacteria（0.5%）;Thiomonas.sp increased significantly at the genus taxonomic level.7.9%in the enrichment increased to 44.8%after enrichment.In addition to Thiomonas.sp,the domesticated microflora mainly included Metallibacterium.sp（11.1%）,Acinetobacter.sp（26.2%）,Sphingobacterium.sp（4.7%）.According to taxonomic analysis of species,Alpha and Beta diversity analysis and significant differences between groups,it was found that the microbial diversity of the microflora decreased after domestication,but the relative abundance of species increased.（4）Research on the application of microflora biofortification shows that when the concentration of thiosulfate is 1500 mg/L,the time required for the complete degradation of thiosulfate in the enhanced system is 8 h,the degradation rate of the original sludge degradation system in 8 h was only 3.13%.Comparing the degradation of other pollutants,it was found that the phenol in the enhanced system was completely degraded at 6 h,and there was a small amount of ammonia nitrogen and COD remaining.However,all kinds of pollutants in the original sludge degradation system have a large amount of residual,the degradation rate of the former is 39.4times and 34.3 times that of the latter,respectively;When the thiosulfate was 3000mg/L,it only took 16 hours for the intensified system to completely degrade the thiosulfate.At the same time,the phenol content in the wastewater was also reduced to zero,while the content of ammonia nitrogen and COD remained slightly;At the same time,the degradation rate of thiosulfate by the original sludge system was 6.6%,and a large amount of other pollutants remained.Finally,when the two systems were completely degraded,the liquid solutions were taken out from the two systems for comparison,and it was found that the water quality of the enhanced system was much clearer and more transparent than that of the original sludge degradation.（5）The microbial immobilization study showed that the immobilized inoculum had a good degradation effect.At 36 h,the degradation rate of thiosulfate by the inoculum with diatomite as a carrier was as high as 100%.The degradation rates of thiosulfate with ethylene and gel beads as carriers were 88.4%,75.2%,and 70.2%,respectively,and the degradation rates were all higher than 70%.The continuous use of the carrier shows that when the thiosulfate is degraded continuously for 5 times,the thiosulfate can be completely degraded within 36-48 h,and it has a high continuous use performance.The degradation effect of the microflora before and after immobilization and the anti-stress effect:when the temperature is 15,20,and 50℃,the degradation performance of the immobilized bacterial agent is better than that of the microflora,and the degradation rate is the largest at 15℃,was 12.2%.In other temperature ranges,the degradation effect of microbial inoculants was better,and the degradation rate of microflora was 10.47%higher than that of immobilized inoculants at 30℃.When the pH is 4.0-6.0,the degradation rate of the microflora is higher,and the difference reaches the maximum at pH 6.0,which is 8.58%.When the pH is 3.5 and7.0-9.5,the degradation rate of the immobilized bacterial agent is always at the peak,at pH 9.5,the difference between the two degradation rates is the highest,which is10.08%. |
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