| The main source of chemical wastewater,its complex pollutant composition,originated from industrial production,and its direct discharge is extremely harmful to the environment.The biological treatment is one of the most promising wastewater treatment methods due to its low cost,high efficiency,and sustainability advantages.However,when facing different types of industrial wastewater,the high salt,high organic matter,and complex composition environment make the bio-based treatment inefficient.Therefore,how discovering microorganisms with high environmental tolerance is the key to improving the efficiency of biological treatment.Based on this,in this study using enrichment culture and plate separation,the ammonia-degrading strain with strong adaptability to the wastewater environment was screened from the high-salt wastewater of pharma the ceutical chemical industry,the nitrogen removal conditions of the strain was optimized,and its treatment ability for actual pharmaceutical wastewater was explored.Second,to solve the problem of microbial inhibition in high-salt chemical wastewater,the salt-tolerant yeast discovered in the previous stage of the research group was used as a biofortifying agent for large-scale high-salt wastewater treatment,and the metagenomic analysis based on high-throughput sequencing was used to reveal the change rule of pollution indicators and the succession rule of microbial communities in the bioaugmentation process.This provides a theoretical basis for the promotion and application of biological treatment of high-salt pharmaceutical and chemical wastewater.Specific research and results are as follows:（1）Research on the structure-activity mechanism of microbial diversity and environmental factors:In order to reveal the internal mechanism of microbial flora and pollutants removal in high-salt pharmaceutical and chemical wastewater,Meyerozyma guilliermondii W2,which has been highly salt-tolerant in the laboratory,was used as a biological fortifying agent to treat high-salt cotton production wastewater.The microbiota and environmental factors were also characterized and studied.The results showed that compared with before biological fortification,The removal rates of COD,NH3-N,and TN in the sewage treatment station increased from 33.2%±1.6%,21.7%±1.0%,7.2%±0.2%to 92.5%±1.4%,95.1%±2.5%,76.4%±1.5,respectively.The results of high-throughput sequencing showed that the abundance of dominant bacterial genera Paracoccus（39.5%）and Truepera（7.4%）increased to 36.4%and 5.8%,respectively,after bioaugmentation.The relative abundance of dominant fungal genera Meyerozyma,Cladosporium,and Aspergillus changed from 2.2%,1.2%,and 1.1%to29.4%,9.0%,and 8.4%,respectively.This indicated that bioaugmentation had a significant effect on the structure of the microbiota.The correlation between microbial community and environmental factors showed that p H value and dissolved oxygen（DO）were the key factors affecting the succession of the microbial community in the process of bioaugmentation,and the pollutant concentration of cotton wastewater had no significant effect on the intensification strain W2.In conclusion,W2 successfully colonized and played a key role in the treatment of high-salinity organic wastewater,which was the main reason for the improved pollutant removal efficiency.This study systematically revealed the dynamic changes and functional prediction of microorganisms in the process of bioaugmentation,as well as the relationship between microorganisms and environmental factors,which laid a solid theoretical foundation for the subsequent large-scale treatment of high-salinity wastewater.（2）Validation of universality of bioaugmentation strain W2 for wastewater treatment:To explore the universality of salt-tolerant yeast W2 for the treatment of different types of wastewater.we took high-salt antibiotic pharmaceutical wastewater as the research object to explore the bioaugmentation effect of W2 on high-salt pharmaceutical wastewater and studied the internal succession mechanism of wastewater microbial community in the process of bioaugmentation.The results showed that the removal rates of COD and NH3-N were increased from 54.3±0.5%and 53.4±1.8%to 88.7±0.9%and 90.9±0.3%,respectively.Saccharimonadales,Paracoccus,and Meyerozyma were the dominant genera during the intensification period,but the abundance of bacteria did not change much before and after the intensification.The abundance of Aspergillus and Candida decreased from 36.2%and12.6%to 1.2%and 5.6%,respectively.The relationship between environmental factors and microbial characteristics showed that Meyerozyma,Desulfuromonas,and Thauera were highly abundant and negatively correlated with antibiotic wastewater pollutants during the intensification period,indicating that these strains played a crucial role in improving the efficiency of pollutant removal treatment.W2 is the main reason antibiotics wastewater pollutants have improved removal efficiency.The application of W2 laid a theoretical foundation for exploring the dynamic changes of microorganisms in sewage,and provided a case study for the future bioaugmentation treatment of pharmaceutical wastewater.（3）Exploration and characterization of high-efficiency wastewater tolerant functional bacteria:In order to explore more high-tolerance functional bacteria of pharmaceutical and chemical wastewater,to relieve the restriction of low efficiency of wastewater treatment under extreme environment by the biological method.In this study,the activated sludge in pharmaceutical wastewater was used as the research object,and the HN-AD strain X4 with strong tolerance to wastewater was screened by enrichment culture and plate separation.Acinetobacter haemolyticus was identified on the basis of its phylogenetic and phenotypic inheritance.The nitrification characteristics of the strain were explored,and the cultivation conditions were further optimized.The results showed that the best nitrogen removal effect of X4 was achieved when the carbon source was sodium succinate,the C/N ratio was 12,the temperature was 30℃,the p H was 9,and the speed was 170 r/min,and the ammonia nitrogen removal rate reached 99.29%within 24 h.In the actual medical wastewater treatment,the removal rate of ammonia nitrogen reached 52.62%,and the chemical oxygen demand（COD）degradation rate of wastewater reached 93.33 mg/（L·h）within 36 h.In summary,strain X4 shows a wide range of temperature and p H stability,and has a low C/N requirement,which has a certain application value in the treatment of high-salt pharmaceutical and chemical wastewater,and provides a new strain source for the biological treatment of chemical wastewater in the future. |
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