Study On Removing Oscillatoria And Humic Acid By Potassium Ferrate(Ⅵ) Pre-Oxidation With Coagulation

The difficult problem of troubling water treatment field at home and abroad was that the algae and organic micro-pollutants effect drinking water. Water safety had been seriously influenced by the bloom events in world scope, especially the filters congestion problems and the threat of cyanobacterial toxins on health had aroused great attention. Humic acid (HA) not only affected the color, odour of the water, but is also the main precursor of THMs. In the natural water body, the humic acid and the algae accompany frequently existed, Therefore, it was great significant that we researched the purification method of including the algae and the humic acid mixture of water. For nearly a decade, the domestic and foreign water treatment workers had done massive research work for separately removing the algae and the humic acid, they proposed some new technical methods. However the research of using K₂FeO₄ preoxidation with coagulation had rarely seen until now.This paper studied the process conditions and mechanism of K₂FeO₄ preoxidating separately including the algae and the humic acid waste water. On this basis, it studied on removing Oscillatoria and humic acid by potassium ferrate (VI) pre-oxidation with coagulation. Studing the settlement time, the dosage of PAC and Kaolin, the concentration of K₂FeO₄ and pH value . Conclusions were as follows:1. The coagulation condition was optimized by orthogonal experiments. The best removal result was achieved using 5mg/L of PAC,24mg/L of kaolin and 2.4mg/L of Potassium Ferrate (VI) with 10 min of holding time and pH value of 6.5. Residual aluminum concentration was 0.125mg/L.The removal rate of turbidity and chlorophyll a was 95.03% and 95.44%. The results showed that along with the quantity increasing, the time of algae's growth inhibition activity was extended. It is a kind of effective method of treating of algae water.2. Studied on removing humic acid by potassium ferrate (VI) pre-oxidation with coagulation. The best removal result was achieved using 10mg/L of PAC,12mg/L of kaolin and 10mg/L of Potassium Ferrate (VI) with 30 min of holding time and pH value of 6.5.3. The containing Oscillatoria and humic acid mixed water was disposed by using potassium ferrate (VI) as the pre-oxidation agent and PAC and kaolin as the co-coagulation agents. The consequence was that the ferrate concentration,PAC and Kaolin respectively being 4mg/L,20mg/L and 8mg/L could improve the removal rate of HA and algae,which value was 91.67% and 90.78% respectively, and the effect was much better than PAC singly. Potassium ferrate(VI) pre-oxidation affected the content and form of residual aluminum. In the best condition the total aluminium concentration reduced by 51.8%, and especially the dissolved aluminum which poisoned human body decreased by 43.9%.