| Drinking water disinfection by-products, mostly caused by adding chlorine and ozone, are of public concern. In this study, a novel technique of composite Fe-Si+Mg-Al alloy filtration material was used both in lab and pilot device in waterworks to remove disinfection by-products, e.g. chloroform, trichloroacetic acid, bromide and so on. The removal rate of disinfection by-products by Fe-Si+Mg-Al filtration material was determined by gas chromatography (GC). The factors of the composition of filtration material, the initial target concentration, input water flow velocity and material height effect on the dehalogenation were also studied. The concentration of ions, color and other quality index of treated water were all tested. The corrosion rate of main depleting Mg-Al alloy in water was studied by methods of extrapolating the Tafel polarization curve, coulometry and linear polarization. The dechlorination effect, potential testing, water resistance and technical parameters of backwashing of Fe-Si+Mg-Al filtration material were researched on the pilot device in waterworks.Owing to the strong electric couple interaction between Fe-Si alloy with more active Mg-Al alloy, the electrode potential of Fe-Si alloy was negatively shifted. As a result, the reductive system was greatly activated. By using Fe-Si alloy in stead of Fe powder, the turbidity in treated water caused by the oxidation of Fe powder in water could be restrained. The continuous working life of the Fe-Si+Mg-Al filtration material was extended by adding consumed Mg-Al alloy particles. Typically, more than50%chloroform could be removed when water flew in velocity of lOm/h through Fe-Si+Mg-Al filtration systems in the thickness of20to30cm. The backwashing period was6days and potential of filtration layer was-700mV～-635mV. The water quality all met Chinese criterions. In the electrochemical experiments, the corrosion rate of Mg-Al alloy in Fe-Si+Mg-Al was0.07～0.3mm/a and its working life was mare than3years. |
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