Research On Denitrification Enhance By Typical Filamentous Algae In Constructed Wetland System And Resource Utilization

In this experiment,c was used to replace the traditional wetland plants,and the filamentous algae type constructed wetland system was constructed to explore the nitrogen removal ability of filamentous algae type constructed wetland system when treating different nitrogen.The influence of environmental factors on the nitrogen removal of filamentous algae was explored,and the resource reuse of filamentous algae was explored.The main experimental contents and results are as follows.1.Three factors and three levels orthogonal experiment was set up to explore the nitrogen removal and water purification capacity of filamentous algae under different light intensity,hydraulic retention time and environment temperature conditions,and to analyze the physiological and biochemical changes of filamentous algae after low temperature.（1）The removal of NH₄⁺-N is greatly affected by environmental factors.In a certain range,improving the light intensity and appropriately increasing the environment temperature are beneficial to improve the removal rate of NH₄⁺-N,and the removal rate of NH₄⁺-N is significantly related to the environment temperature.In this experiment,compared with the hydraulic retention time,the removal of nitrate nitrogen is more affected by the environment temperature.（2）After management with low temperature treatment,the morphology of Cladophora showed some changes,and some of the algae cells died.In this experiment,the recovery rate of Cladophora after low temperature treatment was 62.13%.After a winter,SOD activity decreased,MDA content increased,all of that indicated that the resistance of Cladophora decreased.In conclusion,the ability of nitrogen removal and water purification of Cladophora is greatly affected by environmental factors.Low temperature stress will have a certain impact on Cladophora but most of Cladophora can still survive.2.The filamentous algae type constructed wetland was set up to explore the ability of simulated polluted river water treatment,and to investigate the physiological and biochemical responses of filamentous algae and the changes of microbial community in the wetland system after the constructed wetland treated the simulated polluted river water with different nitrogen under the same carbon nitrogen ratio.And the results are as follows.（1）According to the APHA standard,the water quality of the filamentous algae constructed wetland system was monitored.It was found that the filamentous algae constructed wetland system could effectively purify the simulated polluted river water,especially the NH₄⁺-N.The removal rate of NH₄⁺-N in the control group（CG）and ammonia nitrogen group（AG）reached more than 90%,while the removal effect of NO₃^--N was relatively poor.The TN removal rate of NG group was higher than that of NG was 21.80±9.67%,which was related to the different metabolic pathways of filamentous algae to different nitrogen.（2）16S rRNA targeting microorganisms V3-v4 high-throughput sequencing was used to analyze the effect of different nitrogen on the microbial community in the filamentous algae type constructed wetland.The results showed that the microbial community in the filamentous algae type constructed wetland had different responses to different nitrogen.After 12 cycles,the microbial community in the filamentous algae type constructed wetland system had obvious changes,and the microbial community attached to algae had a high correlation similarity.（3）Through microscopic examination,MDA and SOD detection,chlorophyll content determination,the physiological and biochemical effects of different nitrogen on filamentous algae were analyzed.It was found that the response of filamentous algae to different nitrogen was different.Even at the same C/N ratio,different nitrogen still led to different morphological changes of filamentous algae.There was no significant difference in morphology,chlorophyll content,MDA and SOD activity between NG group and CG group,while the somatic cells of AG group were significantly smaller,chlorophyll content increased and SOD activity was stronger.In conclusion,the filamentous algae constructed wetland can effectively purify the simulated polluted river water.The response of filamentous algae to different nitrogen is different,which leads to different total nitrogen removal rates and different microbial communities when filamentous algae constructed wetland system treats different nitrogen wastewater with the same carbon nitrogen ratio.3.Using different methods to prepare algae-based biochar,to explore the differences of physical and chemical properties of different algae-based biochar.Two kinds of algae-based biochar were used for PPCPs and heavy metal ions adsorption,respectively,to analyze the adsorption process of PPCPs and heavy metal ions.The main results are as follows.（1）Different preparation methods lead to different microstructure,specific surface area and pore size distribution of the two biochar（ZCG and ZCM）.The main crystal in ZCG is Ca CO₃,while the main crystal in ZCM is Ca（PO₃）₂.The difference of crystal is mainly related to different preparation methods of the two biochar.（2）According to the fitting results,the adsorption process of ZCG for ibuprofen and ofloxacin and the adsorption process of ZCM for Pb²⁺are similar to the pseudo second-order kinetic model.The adsorption process of ZCG for ibuprofen and ofloxacin and the adsorption process of ZCM for Pb²⁺are mainly controlled by the chemical adsorption mechanism.The adsorption isotherms of ZCG for ofloxacin and ibuprofen can be described by Freundlich model and Dubinin-Radushkevich model,respectively.The adsorption isotherms of ZCM for Pb²⁺can be fitted by Freundlich model with the highest fitting degree.