| Groundwater with its features of widely distributed high quality and not easy polluted, is being developed and applied more and more extensively. But for the destruction of nature, groundwater has been polluted by Fe2+and Mn2+, so the study of reducing concentration of Fe2+ and Mn2+ to the standards has became the hotspots. Main methods of Fe2+ and Mn2+ removal in groundwater included alkalinization, oxidation, ionic exchange, ozonation and magnetic separation et al. in our country, researchers focus the attention on the study of Fe2+ removal in early times, but few on Mn2+ removal because of lots difficulties, like high expense, complicated method et al. Courses of Fe2+ and Mn2+ removal in theory and application are natural oxidation, contact oxidation and biological oxidation, in which biological oxidation performed better.Two bacteria strains named 4-05 and 11-02 which has high ability of removing iron and manganese has been isolated in our previous works. In this study, they were identified as Pseudomonas sp. and Acinetobacter sp. respectively by traditional identification methods and molecular biology methods. Both 16S rDNA sequences of the' strains have been included in GenBank Database, with accession number of FJ805431 and FJ8054322 respectively.Filtering layer of biological iron and manganese removal is a complex micro-ecosystem; complex inter-relationship existed between bacteria, including synergy effect. The effect of iron and manganese removal by mixed bacteria has been researched in this study. Results showed that the effect of mixed bacteria is better than the effect of only by one bacterium. The effect of iron removal is better when the proportion of 4-05 strain is higher, but the effect of manganese removal is better when the proportion of 11-02 strain is higher. Combined the two solutions, the best combination of the two strains is 25% 4-05 strain and 75% 11-02 strain.Initial iron concentration will affect the removal of manganese, and vice versa. This interrelation has also been researched in this study. Results show that:when the initial concentration of iron is lower to 39 mg/L, the results turned well.the effect of manganese removal is influenced not only by the initial concentration of manganese, but also by the initial concentration of iron. On the contrary, exist of manganese has no influence on iron removal. The strain of 4-05 has better effect of iron removal, and the strain of 11-02 has better effect of manganese removal.Organic material A and organic material B can be the adsorbent of heavy metal ion in water treatment, for its surface properties. They can also provide nutrient for bacterial. This study mixed the bacterial and organic material A or organic material B, researched the growth of bacterial and the removal of heavy metal ion under this condition, the optimum material and its additive amount was defined. The results showed that organic material A and organic material B can absorb iron and manganese in waste water treatment. The performance of iron absorption by organic material A is not good enough as its absorption of manganese, and the iron liberation is too high. However, organic material B can act well in absorption of metals and its liberation of iron and manganese is lower. Except that, the study also defined the optimum recruitment of organic material B is lOg/L. In order to prepare a combined microbe particle with characteristics of easy storage and transportation, non-toxic harmless and convenient operation, organic material B and bacterial were mixed to produce a composite micro-organisms particle. The processes of making this particle are as follows:cultivating the strains, then injects matetrals into the mixture, make granules.Small-scale simulation of filtration column was established, the column is made by PMMA, with inner diameter of 9 cm and height 100 cm,with river sand as the filter and cobbles as the under layer. The depth of river sand and cobbles are 50 cm and 10 cm respectively. The filtration rate maintained in 110 ml/h, and with waterfall aeration as the aeration mode. Organic material B and the strain of 4-05 were added in the column. The results showed that rival sand and organic material B can be the good absorption, except that, organic material B can also promote the growth of microorganism. Living bacteria can reduce the concentration of manganese and iron concentration effectively; the dead bacteria can also absorb the heavy metals. Besides, it is improved that the initial concentration of heavy metals can influence the effect of bio-filter layer, high concentrations of metal ions in solution will destroy the whole bio-filter layer.
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