The Research On Impact Of Natural Organic Matter On The Biological Removal Of Iron From Drinking Water

On the basis of summarizing lots of the related references ,a great deal of experiments had been done to study natural organic matter on biological removal of iron. And the characteristics and mechanism of iron removal from drinking water were researched.The experiments showed that the iron removal in the filter was mainly depended on biological oxidation other than contact oxidation when the influent pH was about 6.5 and DO was 2.5mg/L and the water temperature was 20℃. The biological iron-removal had the advantages of quick oxidation velocity and good removal efficiency and the iron concentration of the effluent that could remain steadily below 0.1mg/L. The biological removal of iron could consist of three stages: firstly diffusion and secondly adsorption thirdly biological oxidation (regeneration), and the third was central. Removal rates of iron abided by first-order reaction kinetic when the influent pH was about 6.5 and water temperature was 20℃, the kinetic constant of the biological iron-removal was 0.81min-1. After adding humic acid, the kinetic constant was 0.8min-1. Various natural organic compound had negative impacts of different degree on the biological iron-removal. The greater the concentration of organic substance or the molecular weight was, and the higher the degree of negative impacts was. After adding FA, the filter period became short. The higher the concentration of FA was, the shorter the period became and the higher the iron concentration of the effluent at the same filter layer was. The greater the concentration of organic substance or the molecular weight was, and the less the removal ratio of ferrous and UV254 and DOC was. Soluble Fe(Ⅱ) complexed by natural organic matter with molecular weight less than 1000 was removed by the biological removal of iron filter. The concentration of organic substance or the molecular weight impacted on the length of the filter period. The greater the molecular weight or the concentration of organic substance was, the longer the length of the filter period was. The test indicated that 12-24 hours provided ample time for iron complexation to occur and that soluble Fe(Ⅱ) complexed by lower molecular weight DOC was more readily removed by biological oxidation.Soluble Fe(Ⅱ)was complexed with lower molecular weight ,especially...