Treatment Of Strontium-Containing Wastewater By Combined Process Of Mechanical Mixing And Microfiltration

In combination with the advantages of chemical precipitation and membrane, themechanical mixing-microfiltration combined process solved the problem insolid-liqiud seperation. The process produced small volume of sludge with a highconcentration factor, and removed efficently the strontium element from thewastewater with a high decontamination factor. The operation of process was stable. Ithas high reliability and a good application potential.The treatment effect wasinvestigated by the mixing-microfiltration combined process when the strontiumconcentration of the raw water or the dose of ferric chloride was different in the earlyinvestigation of our research group.In this paper, the strontium-containing wastewater treatment effect wasinvestigated by the mixing-microfiltration combined process when the temperature orthe dose of sodium carbonate was different. Through the comparison of test indexesand parameters in the process, the performance of the process operation and treatmenteffect of strontium were analyzed and evaluated comprehensively.Firstly, the strontium-containing wastewater treatment effect was investigated bythe mixing-microfiltration combined process when the temperature was6.5℃,17.2℃and26.5℃, respectively. The results showed that the growth of crystal seeds wasinfluenced greatly by temperature in mixing reactor. Under the condition of lowtemperature, the crystal seeds grow slowly. The crystal seeds had small particle sizeand poor sedimentation performance. The effluent from mixing reactor containedmany tiny particles. The membrane pores were quickly blocked, the membraneresistance was increased, the membrane flux was decreased quickly, the amount ofwater treated was affected when the tiny particles from mixing reactor entering themembrane separator. By the end of three tests, the amount of treated water was887L,1992L and1781L, respectively. The treatment effect was impacted by temperaturegreatly. The mean DFs of three tests were9.19,456and686, respectively. The rise oftemperature was advantageous to strontium removal from the raw water, andespecially the change of temperature between6.5℃to17.2℃.As precipitant, sodium carbonate had certain influence on strontium removal inthe process. The treatment effect was investigated by the mixing-microfiltrationcombined process when the dose of sodium carbonate was0.5g/L,0.7g/L,1g/Land2g/L, respectively. The results showed that the crystal seeds had bigger particle size and better sedimentation performance when the dose of sodium carbonate washigher. The effluent turbidity was low and the removal efficiency of strontium waspreferable. By the end of four tests, the mean sizes of crystal particles in the mixingreactor were6.837μm,10.72μm,59.56μm and65.86μm, respectively. The meanDFs of four tests were182,362,537and728, respectively. The increase of pH valuemade subsequent process more difficult when the dose of sodium carbonate increased.