Study On Pre-oxidation And Enhanced Coagulation Of Source Water In South-to-North Water Transfer Project(Handan Section)

The South-to-North Water Transfer Middle Line Project uses open channel water conveyance.The length of the water conveyance line is shallow and the depth is shallow.In addition,the pollutants input by atmospheric subsidence along the way have led to a major change in the quality of the water taken from downstream cities compared to the water source.In this paper,the source water of the center line project?Handan section?is taken as the research object.Aiming at the limitation of seasonal increase of algae content in conventional water treatment processes,a chemical pre-oxidation-enhanced coagulation test study is conducted.The process parameters are optimized,and the decontamination effect of the simulated dynamic process is investigated on this basis,with a view to providing data support for the process operation of the relevant water plant in Handan City.An enhanced coagulation test of the source water from the South-to-North Water Transfer Project?Handan Section?is conducted through a beaker test.The static test parameters are determined as follows:the optimal dosage of coagulant PAC is 20 mg/L,the mixing and stirring speed is 400 r/min,and the stirring time 2min,reaction stirring speed is 60 r/min,stirring time is 15min,after 30 min precipitation,the average removal rates of turbidity in the source water,chlorophyll a,UV₂₅₄54 and COD_Mnn are 85.29%,86.30%,35.71%and 25%.Pre-oxidation enhanced coagulation test using potassium permanganate,sodium hypochlorite and hydrogen peroxide as oxidants.The results show that sodium hypochlorite is economically feasible as a pre-oxidant.The optimal dosage of sodium hypochlorite is 0.5 mg/L,and the optimal oxidation time is 30 minutes.Under these conditions,the removal rate of turbidity in the source water,chlorophyll a,UV₂₅₄54 and COD_Mnn are 94.19%,97.02%,55.32%and 42.31%.Based on the static test,the conventional coagulation and pre-oxidation-enhanced coagulation dynamic tests are performed to simulate the treatment process of the water plant to investigate the purification effect of the dynamic process on the source water.The results show that when the dynamic test device runs stably,the average removal rate of turbidity,chlorophyll a,UV₂₅₄54 and COD_Mnn by the conventional coagulation process is 20 mg/L,the coagulation time is 20 min,and the precipitation time is 120min.They are 92.09%,90.96%,34.87%and 28.86%,and the average residual aluminum content in the effluent is 0.131 mg/L.After the sodium hypochlorite pre-oxidation enhanced coagulation,the dosage of sodium hypochlorite is 0.5 mg/L,the pre-oxidation time is 40 min,the dosage of PAC is 10 mg/L,the coagulation time is 20min,and the precipitation time is 120 min.Turbidity,chlorophyll a,UV₂₅₄54 and COD_Mnn are 0.145NTU,0.24mg/m³,0.030cm^-1,and 1.18mg/L.The average removal rates are96.71%,94.97%,52.6%and 42.30%,and the average residual aluminum content is only0.079 mg/L,the above water quality indicators in the effluent are better than the limit requirements of the"Sanitary Standard for Drinking Water"?GB5749-2006?.