Study On Magnetic Flocculation Technology In Emergency Drinking Water Treatment Of High-turbidity Raw Water And Technological Design

When earthquakes,debris flow,flash floods,and other sudden natural disasters occured,the incompact substances would be washed by heavy rain.The water turbidity increased significantly in a very short period of time and drinking water sources were seriously polluted.coagulation sedimentation method was the most effective treatment of high turbidity water.However,the conventional coagulation sedimentation technology can't meet the requirements of emergency water treatment.The magnetic loading coagulation technology was widely used in the field of emergency drinking water treatment by the advantages of large processing capacity,high efficiency,safe and reliable water quality source.First of all,the water quality of earthquake,floods,typhoons and other typical natural disasters in the case of emergency were studied.The result showed that particle pollutants were washed by the repid water and heavy rain,which leaded to the turbidity increased sharply to about 200-500 NTU.Secondly,the effects of coagulant,coagulant and flux addition on the magnetic coagulation process were investigated and the mechanism of the magnetic powder was investigated.The results showed that,for magnetic coagulation,when the turbidity of raw water was below 200 NTU,the optimum dosages of PAC,PAM and magnetic powder were 10 mg/L?0.2 mg/L and 75 mg/L respectively which gave a turbidity removal rate over 97%and a turbidity of effluent below 3 NTU.Especially,the usage of PAC was reduced over 50%when compared to the conventional coagulation;when turbidity of raw water was 200?500 NTU,the optimum dosages of magnetic powder increased to 150 mg/L,and the turbidity removal rate was over 98.5%.By measuring the Zeta potentail and observing the floc structure,it was found that the mechanism of the magnetic coagulation.The magnetic powder could promotes the coagulation reaction by reducing the Zeta potential in the coagulation reaction system.The floc stucture formed in the magnetic coagulation was more compact.The sedimentation rate was 16 times faster than conventional floc,which facilitated rapid precipitation and separation.Then,based on the experiment,a 5 m3/h magnetic coagulation devise was designed for testing and the result showed that when the surface load was 10 m3/(m2·h)and the turbidity of raw water was 0?100 NTU,100?200 NTU and 200?500 NTU,the turbidity of effluent was below 3 NTU and the removal rate reached 95%,98%and 99.4%respectively,which met the standard of "Sanitary standard for drinking water"(GB5749-2006).When the control voltage was 36 V,the working way of the power pulsation controller was 1 second off after 10 seconds on.Under the circumstance,the magnetic swirl device was separated and recovered with the highest efficiency of 93%.Finally,the preliminary design of the 360 m3/d mobile magnetic loading coagulation emergency water treatment system was finished based on the experimental results of the magnetic test.Magnetic coagulation was suitable for the emergency drinking water treatment of high-turbidity raw water with the advantages of light weights,small size and guaranty of high-quality effluent.This study supported for the design and engineering practice of the magnetic loading coagulation emergency drinking water equipment.