Influence Of Iron Form Distribution On Coagulation-ultrafiltration Process Under The Influence Of Magnetic Field

As a kind of enhanced coagulation technology,magnetic reinforced coagulation has been widely used in water treatment.As a compound coagulant,polyferric sulfate(PFS)has the characteristics of alum density,good precipitation separation and stable removal effect.This study is based on UV-vis spectroscopy characteristics of polymeric ferric sulfate,using impressed electromagnetic field on polymeric ferric sulfate for magnetic control,study the different magnetization time and the effect of magnetic field strength distributions of PFS railway form and in all kinds of iron content of Fe under different conditions the floc properties and slightly polluted water pollutants removal rate and its influence on membrane fouling.The magnetizer is designed and simulated to select the best form to achieve the best effect of pre-magnetization.The magnetizer was used to regulate the magnetization of PFS and observe the change of iron form distribution.Based on the cylindrical magnetizer,the optimal premagnetization effect can be achieved by adopting the helical pipe design as the best form.Under the action of the magnetizer,the ferric salts gradually combine with hydroxyl groups during the hydrolysis process of PFS,and there is a trend of transformation from low polymer state to relatively high polymer state.On the whole,increasing the magnetization time and magnetic field intensity can effectively promote the hydrolysis of flocculant.Under the same magnetic field intensity,the conversion rate from low polymer state to high polymer state is faster when the magnetic field is magnetized for 4-6min.When the magnetization time is controlled at the same time,the conversion rate of hydrolysates will be increased by 1.9%-12.3%with the increase of magnetic field intensity.By comparing the differences of iron morphology distribution in solution under different magnetization modes,the flocculation effect under different iron morphology distribution and the influence on membrane fouling under different conditions were studied.The results showed that under the optimum dosage of 30mg/L of coagulant,the content of Fe(a+b) in effective form was the largest in the solution of polyferric sulfate at 4min of magnetization.The size of flocs formed during flocculation was the largest,about 370?m,and the membrane flux at the stable stage was the largest,about 95L/h·m2.When not magnetized,Fe(a+b) has the smallest proportion.When the treated water samples are directly filtered,the flux is the smallest.Therefore,flocculation,as a pretreatment method,can effectively reduce membrane pollution,and the proportion of effective forms can be increased by adjusting iron shape distribution through external magnetic field to achieve the effect of strengthening flocculation.Improving filtration efficiency has certain guiding significance for practical application.Magnetic powder is stable and can be separated,recovered and reused.The experimental results showed that the best experimental conditions were 200r/min stirring speed and 3min stirring time.The recovery rate of magnetic powder can be as high as 85%,and the recovered magnetic powder will have certain loss in the process of water conservancy and magnetic adsorption,so the removal rate of COD and turbidity in wastewater treatment will be reduced in the process of recycling.