富氧生物膜法修复微污染水源的机理研究

采用弹性立体填料、微孔曝气富氧生物接触氧化法修复上海市受污染的川杨河水，生物填料在进水氨氮浓度2.6～3.1 mg/L和水温20℃～22℃下,7 d自然挂膜培养成功, 氨氮去除率达90%以上。 生化池运行一段时间后，必须根据生物膜厚度和其除污染效率，适时适度冲洗填料和排除池底积泥，以防止好氧生物膜出现厌氧运行状况和影响除污染效果。在川杨河水源水质浊度90～300 NTU、 NH+4-N 0.5～10.0 mg/L、CODMn4.0～10.8 mg/L、污染指数为2～8及生物修复工艺HRT为1.3 h、DO为7.5～10.2 mg/L、g/w为0.5/1的正常运行条件下，观察到膜上的生物相丰富, 微生物种类繁多, 主要是好氧的异养菌和自养菌。生物膜较薄，一般厚度为0.09～0.13 mm，在原水污染物氨氮浓度较低，曝气充足，水中溶解氧浓度高，好氧生物膜传质阻力小、速度快，污染物氨氮的生物降解速率很快，只需较短的水力停留时间，就能达到很高的氨氮去除率。微孔曝气气液传质充分,水中溶解氧充足，膜内无厌氧层存在。好氧生物膜内处于完全的好氧状态，硝化反应比较完全。污染的去除主要是填料上的好氧生物膜在起作用。

REHABILITATION MECHANISM OF SLIGHTLY POLLUTED WATER BY OXYGEN ENRICHMENT AND BIOFILM DEVICE

The authors used the elastic packing for biofilm and fine bubble aeration for oxygen enrichment in the system of biological contact oxidation to rehabilitate the slightly polluted Chuanyang River in Shanghai. Parameters of water quality in Chuanyang River were as follows: turbidity 90～300 NTU, NH+4-N 0.5～10.0 mg/L, CODMn 4.0～10.8 mg/L, and pollution index 2～8. Establishment of biofilm was successful within seven days with the influent water having a concentration of NH+4-N 2.6～3.1 mg/L and temperature 20℃～22℃. The removal rates of NH+4-N was more than 90％. The authors washed the packing and removed the sludge periodically in order to avoid the occurrence of anaerobic condition in biofilm that would decrease the removal rate of the pollutants. Under the normal condition of bio rehabilitation,i.e. HRT 1.3 h, DO 7.5～10.2 mg/L, the ratio of gas to water 0.5, The authors observed a biophase enriched with the bacterial species of various physiological characteristics (aerobic, heterotrophic, and autotrophic). The biofilm thickness was in the range of 0.09 to 0.13 mm and increased with decreasing NH+4-N of raw water. Due to the adequate concentration of dissolved oxygen, the rates of mass transportation and thus NH+4-N degradation were rapid. So,about 90% removal of NH+4-N was achieved within an hour.