臭氧预氧化/MBR工艺处理微污染原水的研究

Ozonation/MBR Process for Treatment of Micro-polluted Source Water

采用臭氧预氧化/膜生物反应器(O3/MBR)工艺处理微污染地表水,通过30 d的稳定运行考察了系统的除污效能,并通过观察膜表面的微观形态对膜污染的机理进行了初步探讨。初始阶段向MBR中一次性投加2 g/L的粉末活性炭(PAC)作为生物载体,并控制水力停留时间(HRT)为0.5 h、臭氧投量为1.5 mg/L。结果表明,O3/MBR系统由于超滤膜的截留作用对颗粒物的去除非常有效,对浊度的平均去除率达到99.3%;对CODMn、DOC、UV254也有一定的去除效果,平均去除率分别为32.6%、18.7%和30.1%。尽管臭氧氧化使水中的AOC浓度有所增加,但经MBR工艺处理后,整个系统对AOC的去除率为13.4%,生物稳定性得到了提高。运行结束后的扫描电镜观察显示,超滤膜的膜孔被污泥层覆盖;通过原子力显微镜观察发现污泥层的表面粗糙不平,这两者均表明污泥层造成了膜污染。尽管该污泥层导致了跨膜压差的增加,但同时也起到了预过滤作用。

The ozonation/membrane bioreactor （O3/MBR） process was used to treat micro-polluted surface water. The pollutant removal efficiency of the system was investigated within 30 days of stable operation. The mechanism of membrane fouling was studied by observing the microscopic morphology of membrane surface. At first, 2 g/L of powdered activated carbon （PAC） was added into MBR as the carrier for bacterial growth. The hydraulic retention time of MBR was 0.5 h, and ozone dosage was controlled at about 1.5 mg/L. The results show that the O3/MBR process has an effective removal of particles due to the interception of the ultrafihration membrane, and the turbidity removal rate is 99.3%. The average removal rates of CODMn, DOC and UV254 are 32.6% , 18.7% and 30.1% respectively. The total removal rate of AOC is 13.4% although AOC is increased after ozonation process, and the biological stability is improved. The SEM and AFM observations show that the membrane surface in the MBR is covered with an irregular and dense sludge layer which fouls the membrane. The sludge layer provides additional filtration function and increases the trans-membrane pressure （TMP） of the membrane.