Experimental Research On Ballasted Coagulation For Treatment Of Polluted Landscape Water

As the main method of landscape water emergency treatment, coagulationsedimentation has the advantages of quick effect, low cost, simple operation and so on.This research take the removal rates of the turbidity, chromaticity, COD, TP, NH3-N andTN as study index, WeiJin river water in Tianjin was tested by ballasted coagulationtechnology. Determine the optimum combination of loading agent, coagulant, coagulantaids and mixing conditions. The effects of the factors on the coagulation and the removalmechanism were analyzed. The change of water sample’s acute toxicity before and aftertreatment was investigated by using photobacterium phosphoreum502.The treatment effectof ballasted coagulation was analyzed based on the physical and chemical indicators. thusproposed the city landscape water emergency treatment plan. Through the analysis of thedata, the emergency treatment plan of landscape water was put forward, it provides areference for the treatment of polluted landscape water.The coagulant PAC and PFS, loading agent magnetic powder and micro-sand werecompared, it determined the optimum combination is magnetic powder+PAC+PAM.Then the dosage of reagents, dosing sequence, stir conditions and time for sedimentationwere determined by a series of static tests and orthogonal tests. With the optimum condition,polluted WeiJin river water was processed by magnetic ballasted coagulation. The results ofexperiment indicated that the average removal rates of the turbidity, chromaticity, COD,NH3-N and TN were92.53%,84.12%,63.81%,88.38%,35.77%and33.05%,the effluentindices could reach the level Ⅴ of National Surface Water Standard. The raw water ofWeiJin river contain much nitrogen and phosphorus, the TLI greater than80, it belongs tosevere eutrophication. During rainy season, NH3-N and TN removal of severe polluted river water were poor, the removal rates were lower than20%.The biological toxicity of water samples before and after treatment was investigatedby using photobacterium phosphoreum. The result shows that the relative luminosity ofsamples above90%, biological toxicity is low and the relative luminosity of sample aftertreatment has no obvious change, so ballasted coagulation method will not affect thetoxicity of WeiJin river.Compared with the traditional coagulation, ballasted coagulation technology can raisethe efficiency of coagulation, reduce the dosage of coagulant, shorten the time forsedimentation and it don’t affect the toxicity of raw water, so it can be used as an effectiveemergency treatment of landscape water.