The Process Of Remediating Nitrogen Polluted Water By Combining Aquatic Plants And Microorganisms

Bioaugmentation with plants and microorganisms as the core is a key technology widely used in the in-situ treatment and ecological restoration of polluted water bodies.The combined application of the two technologies in water restoration effectively solves the deficiency existing in the application of single technology.However,the research on the process and effect of plant-microorganisms combined in water restoration still needs to be further studied.In this study,highly efficient composite water purification bacteria were constructed and immobilized,and the complex of bitter grass ecological interface was prepared to study the purification effect and microecological process of the remediation of nitrogen-polluted water by combining microorganisms emergent plants and bitter grass ecological interface were studied.The main research results are as follows:（1）Through the mixed culture and PCR-DGGE monitoring analysis of water purification functional strains,it was determined that strain ZH14（Pseudomonas）could be mixed with ammonia oxidizing bacteria AZH15（Delfordii）,AOZ1（Pseudomonas）and COD-degrading bacteria BSK9（Bacillus）to form complex bacterial combinations M1,M2,M3 and M5.The removal rates of ammonia nitrogen,total nitrogen and COD at 48h were 83.6%（M5）-86.3%（M3）,29.8%（M5）-39.7%（M1）,and 82.0%（M5）-89.2%（M1）.All the functional strains that could be mixed culture had good nitrogen removal ability.（2）Using natural palm silk carpet as growth substrate,the bitter grass ecological interface was prepared,which could effectively inhibit sediment release.Simulated polluted water purification experiments showed that the amount of NH₄⁺-N removed from the ecological interface of Vallisneria to ammonia nitrogen concentration of 2-2.5mg/L and 4-5 mg/L was about 46.85-65.15 mg·m^-2·d^-1,TN removal was about 29.13-41.8 mg·m^-2·d^-1.（3）The process of ammonia nitrogen wastewater treatment with concentration 2-2.5 mg/L and 4-5 mg/L by combinating bitter grass ecological interface with immobilized compound bacteria was studied.After 8 days of treatment,the removal rates of ammonia nitrogen and total nitrogen increased by 51.5%,82.6%and 54.6%,58.8%,respectively,compared with the control.The immobilized bacteria enhanced the ability of total nitrogen removal.The high-throughput sequencing analysis of bacteria in the treated water showed that the association of the ecological interface and immobilized bacteria significantly increased the diversity of bacteria and denitrifying bacteria,and the bacterial community structure changed significantly.The interaction between the ecological interface and immobilized bacteria changed the bacterial community structure of the polluted water,increased the abundance of Pseudorhodoferax bacteria,and promoted the removal of ammonia nitrogen and total nitrogen.In this process,Vallisneria played a leading role.（4）The process of ammonia nitrogen wastewater treatment with concentration 2-2.5 mg/L and 4-5 mg/L by combining immobilized compound bacteria with Thalia dealbata、Canna indica and Iris tectorum Maxim was studied.After 8 days of treatment,The removal rates of medium concentration ammonia nitrogen and total nitrogen increased by 32.0%,39.2%,25.9%and 36.8%,37.6%,26.0%compared with the control group,respectively.The removal rates of high concentration ammonia nitrogen and total nitrogen increased by 25.3%,20.5%,21.5%and 42.9%,27.6%,20.7%,respectively.The combined application of emergent plants and immobilized compound bacteria only significantly enhanced the removal effect of total nitrogen.High-throughput sequencing analysis of bacteria in the treatment process showed that combined remediation reduces bacterial diversity in water bodies,but significantly increased the relative abundance and diversity of denitrifying microorganisms,thus promoting the removal of total nitrogen,and plants played a leading role in this process.In this study,it was determined that there was a significant plant-led interaction in the treatment of nitrogen-polluted water by plants and immobilized microorganisms.The effects of the ecological interface on bacterial community structure and diversity in water were stronger than those in emergent water,and the removal efficiency of ammonia nitrogen and total nitrogen was higher.The results of this study will provide theoretical basis and technical support for the construction of three-dimensional ecological floating island and the application model of plant-microbial combined remediation technology for nitrogen polluted water in situ bioremediation and ecological restoration.