Effects Of Microcystis Aeruginosa On Fluoride Removal By Different Coagulants

Fluoride is a necessary element to the human body,and it is mainly intaked from drinking water.Long-term exposure to high-concentrated fluoride leads to dental and skeletal fluorosis.In our survey,fluoride contentration in surface water in a region of northern China exceeds the standard and is accompanied by eutrophication.The eutrophication of water will cause the massive growth of algae in the water.Microcystis aeruginosa,a typical cyanobacteria,was selected as the research object and explored from the aspects of the types of coagulants and the effects of the dosage of algae on the p H of organic matter.The aim is to explore the mechanism of coagulant-algae-fluoride and realize the efficient removal of fluoride in water containing algal cells.The conclusion can be drawn by experimental investigation:（1）The experimental results of algal cells cultured in fluorine medium showed that the assimilation and absorption of F^-by algal cells themselves was weak.（2）When the coagulant was AlCl₃,within a certain dosage range,algal cells promoted the production of flocs,and more Al was fixed in the loose and porous flocs,which had a significant promoting effect on the removal of fluoride.Excessive AlCl₃caused serious damage to algae cells and release of intracellular organic matter（IOM）,which interferes with the effect of fluoride removal.（3）The fluoride removal ability of FeCl₃ through coagulation was lower than that of AlCl₃,and Fe fixed in flocs containing algal had no obvious promoting effect on fluoride removal.FeCl₃ had a stronger affinity with HA in algal organic matter（AOM）than AlCl₃.The flocs formed by FeCl₃ and HA hadn’t good fluoride removal ability.The p H value of FeCl₃ decreased greatly due to hydrolysis,and high concentration of Fe³⁺interfered with the detection of 3D-EEM.（4）Al₁₃ achieved more than 90%fluoride removal rate,mainly through ion exchange,substitution and hydrogen bonding to achieve fluoride removal.Algal cells and AOM inhibited the reaction of Al with fluoride.At all the set dosage,the algal cells showed inhibitory effect on the removal of fluoride.Al₁₃ at high dosage not only maintained high fluoride removal performance,but also maintained the integrity of algal cells to a large extent.