Synergistic Removal Of Sulfate And Hardness From Water By Double Precipitation Method

There are a lot of methods to remove the sulfate and hardness, but these methods can only remove sulphate alone or hardness. This experiment research goal is to remove sulphate and hardness at the same time, strive to provide feasible method for removing sulfate and hardness.In order to reduce the water cost, realize the engineering use, improve the quality of drinking water.The study found that under the condition of alkaline, Ca2+, SO42-, Al3+, OH-,etc can be combined to generate complex precipitation CamAln(SO4)x(OH)yzH2O, which can remove sulphate and hardness at the same time.This experiment study found, CaO or Ca(OH)2and AICl3·6H2O together is a kind of high efficient desulfurizer, can effectively remove the sulfate in the water.. Experimental results using CaO and AICl3·6H2O to remove sulfates show that,sulfate initial concentration of500mg·L-1,the removal rate as high as88.19%. The best test conditions for:0.70g·L-1CaO,0.60g·L-1AICl3·6H2O, the reaction time is40min, the stirring speed of50r·min-1, pH should be greater than11.0.In addition,when the use of Ca(OH)2and AICl3·6H2O test, the best test condition is:0.70g·L-1Ca(OH)2,0.60g·L-1AICl3·6H2O,40min reaction time, stirring speed100r·min-1, pH≥11.0.Experimental research also found that a small amount of CaO, AICl3·6H2O under a small amount of NaOH auxiliary can play the function of removing sulfate and hardness.According to the relevant data shows,the quality of drinking water sources in region of Ningxia is poor, and several indexes perennial exceed the limit, which sulphate is more pro minent. Due to the local water treatment technology behind, and can not effectively reduce the sulfate concentration.Through experiments of local actual raw water proofed that CaO or Ca(OH)2and AICl3·6H2O have the ability to significantly reduce the concentration of sulfate in water.For the initial sulfate concentration of about350mg·L-1of the Haizixia Reservoir water, after treatment, the residual sulphate content was below90mg·L-1. For the initial sulfate concentration of about470mg·L-1of the Hejiawan Reservoir water, after processing the residual sulphate content is about160mg·L-1. And the experimental results of grid flocculation-inclined plate sedimentation tank process combined with additive agent indicate that,process equipment can run stably for a long time,and the effluent water quality is good.Sulfate, hardness, turbidity, etc do not exceed standards.In addition, this process method, less dosage, easy operation, simple equipment, easy to implement engineering.