Research And Application Of Supersaturated Dissolved Oxygen Technology Combined With Magnetization Technology In The Improvement Of Water Quality ——Taking The South-to-North Water Diversion Project Of China As A Pilot Project

Water resources are the basis of the natural environment and an important organic component of comprehensive national strength.The total amount of water resources per capita in China is low,and the uneven distribution of water resources is higher in the south than in the north.However,with rapid economic growth and a sharp increase in water consumption,the problem of water resources has become an important factor restricting economic development.To alleviate this contradiction,the state spent considerable manpower and material resources planning and implementing the south-to-north water diversion project.The three sides of the middle route project are hard,the flow field is single,the climate along the way is changeable,the atmospheric dry and wet deposition and the internal discharge of groundwater and other factors lead to changes in water quality during long-distance transportation.Although traditional water quality improvement technology has been relatively mature in the treatment of rivers,lakes,and other water bodies,the existing water quality improvement technology can not meet the special requirements of the middle route project.Therefore,in view of the hidden dangers existing in the change in water quality in the South-to-North Water Transfer Project,the development of water quality improvement technology in the process of water transportation is of great significance to ensure the water quality safety of the national strategic project.In this study,a new composite technology-supersaturated dissolved oxygen magnetization（SDOXM）was developed based on the theory of supersaturated dissolved oxygen technology and magnetization technology.Taking the Middle Route of the South-to-North Water Transfer Project as a pilot project,the effects of SDOXM compound technology on microbial activity,phytoplankton community structure,and removal of the main nutritional indices in the Middle Route of the South-to-North Water Transfer Project were studied at the hub of the Baihe sluice gate in Henan Province.For static and flowing water bodies,this study was divided into two parts:static and dynamic experiments（artificial aquatic plant group and no artificial aquatic plant group）.The main results are as follows.1.The SDOXM technology combines supersaturated dissolved oxygen technology with water magnetization technology,which can effectively increase the concentration of DO in water.The experimental results show that after SDOXM treatment,the highest value of DO in static experiment is 38.7 mg/L,and the highest value of DO in downstream connection section and delay flume in dynamic experiment is 19.12 and 18.33 mg/L respectively.The system can not only improve the oxygen transfer rate and efficiency in water,but also maintain the supersaturated state of DO concentration for a long time（more than three days）.2.The SDOXM technology can effectively remove the main nutritional indices in water:NH₄-N,NO₃-N,COD_Mn,TN,and TP.The highest removal rates for each index in the static experiment were 48.11%,30.40%,20%,28.65%,and 27.96%,respectively.The highest removal rates of each index in the dynamic experiment were 57.22%,11.47%,22.86%,13.15%,and 100%.3.During the course of the study,the introduction of artificial aquatic plants improved the removal rate of the main detection indicators,and the sediment beds and aquatic plants in natural watersheds and lakes could provide carriers for microbial proliferation,indicating that SDOXM composite technology can play a better role in natural watersheds.4.The SDOXM technology enhanced microbial activity by providing a good environment for water bodies,and the highest growth rate of relative light units（RLU）of ATP was 265%during the experiment.In addition,the SDOXM system can improve the phytoplankton community structure,and the phytoplankton community structure changes from diatom cyanobacteria to diatom cyanobacteria.5.Based on the removal effect of the nutrition index under various operating conditions during the study period,the optimal operating conditions of the SDOXM system we evaluated,and the operation cost of this technology in the practical application of the middle route of the South-to-North Water Transfer Project was estimated.The results show that the operating cost of this technology is low,and the annual operating cost is 0.03 yuan per ton of water.