固体碳源填料床生物反应器去除水中硝酸盐的研究

Nitrate removal of water using solid carbon source packed-bed bioreactor

采用室内试验装置,研究了以可生物降解聚合物材料(BDPs)变性淀粉为碳源和生物膜载体的填料床反应器对水体中硝酸盐的去除效果及其影响因素。结果表明,反应器能有效去除水中的硝酸盐目.试验过程中未发现亚硝酸盐积累;温度对反应器的反硝化速率有很大的影响,在14～30℃范围内,反硝化温度常数K=0.03;水力停留时间对反硝化反应起重要作用,硝酸盐去除率随水力停留时间的延长而提高,但反硝化速率则随水力停留时间的延长而降低。变性淀粉扫描电子显微镜的观察结果表明,变性淀粉表面形成许多空洞结构,扩大了微生物附着生长的表面积,有利于微生物的生长。

The modified starch that in the form of biodegradable polymers pellets was investigated as the sole carbon source and the only bioflim carrier for the microorganisms to remove 0itrate from wastewater in packed-bed laboratory reactors. The reactors routinely used were cylindrical PVC columns, 60 cm high and 10 em inner diameter, packed with modified starch up to 35 cm high and with a thin layer of glass wool placed at each end. The experimental results indicated that the modified starch served as carbon source started up fast, and nitrate was effectively removed and the accumulation of nitrite was not observed in the biological denitrification continuous reactor. When the water temperature was （ 29 ± 1 ）℃ and the HRT was 6 h, the nitrate removal efficiency was higher than 90%. The temperature markedly affected the denitrification process. High temperature helped to stimulate the denitrification. The denitrification rate at 30 ℃ was more than twice as that observed at 14 ℃, which could be explained by the bacteria increasing at high temperature. The temperature constant of denitrification was 0.03 when the temperature was in the range of 14 - 30 ℃. The hydraulic retention time （HRT） played an important role which influences the denitrification process. When the HRT was increased, the nitrate removal efficiency was increased and the nitrate removal rate was declined, respectively. The HRT had little on nitrite concentration in effluent. When the influent nitrate concentration was 150 mg/L and the temperature was （29 ± 1 ） ℃ , the nitrite accumulation occurred in effluent below 1 mg/L at the HRT ranged from 0.8 h to 9.2 h. The experiment result indicated that pH in the effluent water was stable. During the continuous study, pH in the effluent water increased and ranged from 7.39 to 8.12. The SEM observation indicated that biofilm was formed on the modified starch and consumed the starch surface. In addition, lots of cavity could be formed on the modified starch surface, which increased the area and be propitious to the growth of the microorganism.