Study On Algae And Humic Acid Removal By Enhanced Coagulation With Alternating Electromagnetic Field

A series of drinking water safety problem by algae, humic acid and other organicpollution cause widespread concern. Magnetic field has a character which can transferenergy and change the material microstructure, so their physical and chemical propertiesare affected. Magnetic technology has been widely applied to water treatment field.Magnetic field combined with coagulation achieves good results. PFS coagulant is easilymagnetized as a result of Fe3+. Improving electromagnetic flocculation performance isstudied by increasing the stability and utilization of PFS based on the theoretical research-applied research-validation studies technical route, when liquid PFS coagulant ismagnetized by self-made alternating electromagnetic device.Chlorella cultivated in the laboratoryare are adopted for electromagnetic flocculationexperiments, using the optical density to estimate biomass.The results show that theoptimal conditions are the dosage80mg/L, the current intensity1.0A, the frequency75Hz,the magnetization time3min, at pH8.0. Then the removal rate of algae is high, reaching90.7%. Compared with conventional flocculation, the removal rates under same dosage arehigher. the coagulant dosage saves12.5%, the algae removal rate improves5.7%. Chlorellais all wrapped in floc-compacting. The order of each factors which can influence theefficiency is that pH> magnetizing time> current intensity> dosage.In Tongyu River water electromagnetic flocculation experiments, The results showthat the optimal conditions are the current intensity0.6A, the frequency50Hz, themagnetization time4min, at pH8.0. Then the removal rates of algae and turbidity are high,reaching96.4%and92%. The removal rates of algae and turbidity improve6.8%and6.3%.The coagulant dosage saves20%. Algal cells are embedded flocs compactly. The pH inmagnetization group are higher than the pH of conventional flocculation, theelectromagnetic field may improve the stability of PFS. The order of each factors whichcan influence the algae removal is that pH> dosage> current intensity> magnetizing time; The order of each factors which can influence the turbidity removal is that pH>magnetizing time> dosage> current intensity.In Humic acid electromagnetic flocculation experiments, the coagulation performanceof PFS is compared under different current intensity, magnetization time and frequencyusing of UV290as an evaluation index of humic acid. When setting current intensity1.0A,the frequency75Hz, the magnetization time3min, humic acid removal rate reaches62%;when setting current intensity0.6A, the frequency50Hz, the magnetization time4min,humic acid removal rate reaches62.1%.Electromagnetic flocculation process takes the advantages in having higher removalefficiency, less dosage using, better sludge performance, economy and environmentprotecting. It provides a promising future that algae and humic acid removal byelectromagnetic flocculation.