Water Quality Monitoring Of Tianfumiao Reservoir In Huangbai River Basin And Study On New Methods For Removal Of Cyanobacteria

In recent years,with the increasing eutrophication of water bodies,the frequency of algal blooms has also increased significantly.The algal bloom phenomenon frequently occurs in reservoirs of drinking water sources.Among the algae species from algal blooms,the potential risk of cyanobacteria as a source of toxic algal species in drinking water sources cannot be ignored.Tianfumiao Reservoir is a medium-sized reservoir such as III,which is the main source of industrial and agricultural water as well as domestic water in Yichang City.The industrial pollution and domestic pollution brought by the developed phosphate ore enterprises in the basin and the dense population have released a lot of nitrogen and phosphoros into Tianfumiao Reservoir,resulting in deterioration of water quality,even algal blooms.Thus,it is necessary to improve water quality of Tianfumiao Reservoir and control algal blooms through the implementation of conservation projects.For this purpose,it is important to monitor the changes in water quality and algae in Tianfumiao Reservoir before and after the implementation of the project,and to develop novel and more effective environmental-friendly algal bloomcontrol methods and techniques.Therefore,this paper first provided the monitoring results of Water resources protection project for Tianfumiao reservoir,then selected the most toxic algae i.e.Microcystis aeruginosa as the objective to investigate its removal methods using the green,safe and non-toxic nanomaterials and natural minerals.The purpose of this paper was to provide insight into the influence of nanomaterials and natural minerals on the growth of Microcystis aeruginosa strains,and a scientific foundation for removal of Microcystis aeruginosa in eutrophic lakes and reservoirs.The specific research contents and main conclusions are as follows:1.Take Tianfumiao Reservoir as the research object,and monitor the changes in water quality and algae density both inside and outside the area before and after the implementation of the ISSA PGPR（in situ ecological restoration technology）and ecological floating island protection project of the Tianfumiao Reservoir.The results showed that during the operation of ISSA PGPR water treatment project,the difference in total phosphorus value was small,and the total nitrogen value in the treatment area was slightly larger than outside the area.After the construction of ecological floating island,the water density of total nitrogen,total phosphorus and algae outside the area was higher than that of the construction area.The highest removal rates of total nitrogen,total phosphorus and algae were 42.66%,29.41%and15.51%,respectively.In the monitoring of algae species Diatom,Chlorophyta,Pyrrophyta,Euglena and Cyanobacteria were found in the water of Tianfumiao.The representative species of algae in the reservoir area were diatoms and cyanobacteria and the ISSA PGPR and ecological floating islands.Under the treatment by the two projects,the algae density values decreased significantly.2.The nano-particles BiOBr were loaded on the fabric in order to solve the BiOBr recovery problem in the removal of Microcystis aeruginosa under visible light.Through single-factor experiment,it was found that the removal rate of chlorophyll a was best when the reaction concentration of BiOBr/fabric 0.09 mol/L,the algal are in the death period,visible light illumination,and the reaction p H was weakly acidic or weakly alkaline.In the BiOBr/fabric to remove microcystis aeruginosa in the process of monitoring the changes of dissolved oxygen in the reaction liquid,to explore the active species,observation of algal cell morphology changes after processing and the change of cell membrane integrity.The results showed that under the condition of illumination,BiOBr/fabric consumed O₂ to produce strong oxidizing free radicals on the surface of BiOBr,which can degrade and oxidize photosynthetic pigments,phycobili proteins and polyunsaturated fatty acids on cell membrane,leading to the collapse of photosynthetic function,inhibition of protein synthesis,and peroxidation of cell membrane lipid.Thus,destroy the algal cells were completely destroyed and their growth were inhibited.3.The optimum adsorbent was selected by comparing the removal rate of chlorophyll a from 11 natural ores,and it shown that olivine had the best performance for chlorophyll a removal.Results from the experiments of single factors indicated that the optimum conditions for chlorophyll a by olivine were as follows:olivine concentration 1.5 g/L,algal density<1.7×10⁶cells/m L,reaction temperature of 15°C or 35°C,and weak acidic or alkaline medium.Through monitoring the Zeta potential and nutrient salt during the reaction and observing the surface structure of the microcystis aeruginosa after the reaction,it can be concluded that the natural olivine was mainly adsorbed to the microcystis.The positive charge on the surface of the natural ore and the negative charge on the surface of the algae cells reduce the surface charge of algae cells,which made the cells lose their stability and form a precipitated aggregate.In addition,natural olivine adsorbed nutrients during the reaction process,resulting in nutrient depletion of algal cells,thus inhibiting the growth of algal cells.4.The removal of chlorophyll a from Microcystis aeruginosa was carried out using four kinds of surfactant-modified goethite,and the best removal effect of chlorophyll a was ODTMA（octadecyltrimethylammonium bromide）/goethite.By simulating water environmental factors,it was found that ODTMA/goethite had the best removal rate of chlorophyll a when the catalyst concentration was 50mg/L,the temperature was 35°C,light illumination,and the reaction p H was weakly acidic or neutral.Changes in TOC（Total Organic Carbon）in the reaction solution were monitored during the removal of Microcystis aeruginosa by ODTMA/goethite,and changes in surface structure and cell membrane integrity of the algal cells after reaction were observed.Combined with the changes in the physiological parameters of Microcystis aeruginosa cells,it can be seen that on the one hand positively charged carbon chains can trap and bind negatively charged algae cells.The alkyl chain penetrates the algal cell membrane,and changes the integrity of the phospholipid bilayer,causing the membrane to rupture,and reacts with proteins and nucleic acids in the algal cells,relaxes the bridges between cellulose molecules,or inhibits protein synthesis.Goethite,on the other hand,produces strong oxidizing free radicals that attack the algal cells under the illumination of light,leading to the exudation of organic matter in the algal cells,thereby suppressing the growth of algal cells.