固定化微生物-纳米铁的制备及对高氯酸盐的降解

Preparing immobilized microbe-nanometer zero-valent iron and the degradation ability of perchlorate

应用琼脂制备包覆型微生物-纳米零价铁复合物,并进行干燥处理,研究该复合物降解高氯酸盐的性能及活化、海藻糖、保存时间对降解性能的影响。微生物采自污水处理厂二沉池的活性污泥并驯化4个月。采用液相还原法制备纳米铁。纳米铁为直径约80 nm的球形颗粒物。复合物表面呈非晶型的疏松结构,其中直径5μm左右的球形团块是活性污泥的颗粒结构。活性污泥微生物可在12 d内将初始质量浓度50.0 mg/L的高氯酸降解至检测限以下,反应拐点出现在第8 d,显示其具有高氯酸盐自养性能。制备时添加海藻糖并经活化、保存7 d的复合物可在18 d内将初始质量浓度50.0 mg/L的高氯酸降解至检测限以下,反应拐点出现在第9 d。未活化组在18 d内将高氯酸盐质量浓度降低了8%,说明活化对复合材料降解高氯盐的性能有重要作用。未添加海藻糖的复合物反应拐点为第12 d,比添加海藻糖的迟了3 d,表明海藻糖在一定程度上可保护其微生物活性。保存30 d和保存7 d的复合物的降解性能没有显著区别,表明复合材料可长期保存而不失生物活性。

This paper is aimed at reporting the study of the preparation method of immobilized microbe-nanometer zero-valent iron and its degradation ability of perchlorate. In our experiments, we have studied the composite＇s percholrate degradation ability, trying to make clear the factors affecting its degradation ability, including adding trehalose, activation, and the preservation period. Microbes come from the second clarifier of Tianjin rural sewage treatment plant and has been acclimated for 4 months. The method of making NZVI is liquid-phase reduction. The pictures of NZVI via transmission electronic microscope indicate that it is a round-like particulate with a diameter of 80 nm. The pictures of the composite via scanning of electronic microscope indicate that it is in an amorphous state with 5 μm round masses on its surface. The microbes of the sludge degrade 50.0 mg/L perchlorate in 12 d with a reflection point on the 8th day,which appears to be the autotrophic ability of perchlorate. By adding trehalose to its formation and the composite was activated and preserved in the air for 7 days, perchlorate was degraded in 18 d with a reflection point gained on the 9th day. Its degradation ability proves to be a bit lower than that of the control group. 50.0 mg/L perchlorate is degraded by 8% in 18 d by the composite without being activated. This suggests that the activation plays an important role in promoting its degradation ability. However, when trehalose was not added, the composite degraded perchlorate totally in 18 d with a reflection point on the 12nd day. This implies that the microbial activity of the composite has been protected by trehalose to some extent. Therefore, comparing the degradation ability of the composite preserved for 30 days with 7 days, no significant difference can be found between the two methods. The result has thus shown that the composite can be preserved for a long time without losing its degradation ability. This particular feature we have discovered can provide a basis for its industrial production and practical application.