Effect Study On Enhanced Coagulation Of Low Turbidity And Micro-Polluted Water By Recycling Filter Backwash Water

As a typical low turbidity drinking water sources, the water of lakes and reservoirs has characteristics of low particulate concentration, small particle size, r strong hydrophilic organic matte, low collision and gathered efficiency,so it gives waterorks a great trouble.The backflow technology of filter backwash water for its own characteristics of high aluminum, ferrous metal hydroxide and suspension colloid particle concentration, so filter backwash water has good processing effect on low turbidity micro-polluted water.It is the research of enhanced coagulation experiment on low turbidity micro-polluted water. The hydrolysis form and coagulationt of aluminium sulfate, three aluminium chloride and aluminium polychlorid was contrast further investigation of the aluminum system coagulating agent and the coagulant aid of potassium permanganate,hydrated manganese dioxide was combined for turbidity removal and decontamination ability. Then this paper studies the aluminium polychlorid and filter backwash water combined to Zeta potential,turbidity, organic matter and water residual aluminum coagulation effect.In addition, through the miniature online reflux device inspected the potassium permanganate/manganese dioxide/filter backwash water combination for low turbidity micro-pollution of coagulation characteristics (turbidity, particles,organic matter) and safety (residual aluminum and disinfection by-products).Test results show that:aluminium polychlorid had the highest levels of Alb, and show the best flocculation effect the in series aluminum salt coagulants potassium permanganate reduced the water residual turbidity and organic matter and residual aluminum, while the effect of manganese dioxide had the same functional characteristics and the turbidity removal and lower residual aluminum aspects was more outstanding.Only using the filter backwash water can’t reduce the raw water turbidity, and will lead to the rise of CODMn content, but it had a certain removal effect for UV254.Filter backwash water and aluminium polychlorid combined for low turbidity micro-polluted water has good processing effect, but for different Zeta potential its treatment effect had a very big difference.When Zeta potential was11mV, filter backwash water had a good removal efficiency on turbidity.Zeta potential close to0mV, filter backwash water have a good treatment effect on turbidity and CODMn, UV254, Alp and AlD.Zeta potential closed to+4mV, filter backwash water caused the turbidity and CODMn, AlP, AlD soared, but the removal rate of UV254was improved.Through the impact load contrast study found that the improvement of turbidity can improve the efficiency of coagulation, the turbidity of settled water was higher than filter backwash water reflux.The improvement of humic acid content significantly reduced the water Zeta potential and turbidity, but raised the content of.solubility of AlD.;pH has a important effect in the removal efficiency of FBWW was the highest for water soluble organic matter at the pH closed to6.The CODMn content of settled water reach the lowest at the pH closed to7.The minimum value of turbidity was at pH closed to8.In the potassium permanganate/manganese dioxide/filter backwash water and aluminium polychlorid combination batching processes, the settled water of manganese dioxide and aluminium polychlorid combination process reach the lowest content of turbidity and colloid aluminum, and the settled water of manganese dioxide/filter backwash water and aluminium polychlorid process was the lowest of CODMn, THMs, solubility aluminum.