Study On Removal Of Microcystis Aeruginosa(MA) By Enhanced Coagulation-dissolved Air Flotation Process

Microcystis aeruginosa(MA) is the main algae in entrophication water, which produces harmful pollutants like Microcystins. The paper is based on the pollutant problem of drinking water and research the effect factor and process parameter of enhanced coagulation- dissolved air flotation process by inorganic polymer flocculant. test the effect of the dosage of inorganic polymer, pH, ion strength, mixing intensity and time, flocculation intensity and time, dissolved air ratio and dissolved air ration in flocculation, and confirm the best range of different factor, the research result shows:Polyaluminum Chloride(PAC) is better to keep removal efficiency than ALS, especially above 0.087mmol/l, as low dosage, and PAC have a wide range of dosage and high stability. Polyferric Chloride (PFC) has a better removal efficiency than FCL, while high dosage, PFC and FCL has almost the same removal efficiency, so confirm the PAC and PFC as the best flocculants. The best dosage (by Al3+) of PAC is 1.39mmol/l, The best dosage(by Fe3+)of PFC is 0.56mmol/l, The best dosage (by Al3+) of ALS is 0.087mmol/l, The best dosage (byFe3+) of FCL is 0.74 mmol/1.For the best dosage of flocculants, As for PAC, confirm the best pH is about 6.06-8.38; As for PFC, confirm the best pH is about 6.46-8.73; As for ALS, confirm the best pH is about 5.85; As for FCL, confirm the best pH is about 8.35.As PAC for flocculant, lower ion strength is better for removal; As PFC for flocculant, higher ion strength is better for removal; As for ALS, higher ion strength is better for removal of turbidity and chroma, while medium ion strength is efficient for removal of organic substance; As for FCL lower ion strength is better for removal.As for PAC, the mixing intensity G=500s-1, mixing time(t)is 60s, the flocculation intensity is 50s-1, flocculation time is 5 min; as for PFC, the mixing intensity G=750s-1, mixing time(t) is 90s, the flocculation intensity is 50s-1, flocculation time is 5 min.The best dissolved air ratio research shows: As PAC for flocculant, 10% dissolved air ratio is efficient to keep good removal efficiency; As PFC for flocculant, 10%-12% dissolved air ratio is efficient to keep good removal efficiency.The best dissolved air ratio in flocculation shows: As for PAC, dissolved air proportion 3/7 is good to keep removal efficiency; As for PFC, dissolved air proportion 5/5 is good for PFC to keep removal efficiency, and better than the traditional effect.