膜法富氧曝气和粗内径对外置式中空纤维膜生物反应器性能的影响

Influence of oxygen-enriched aeration with membrane and wide-diameter on performances of recirculated membrane bioreactor(RMBR)

膜法富氧曝气可以提高外置式膜生物反应器（RMBR）污水处理负荷，处理效果好，出水无色无味，固体悬浮物（SS）未检出，浊度小于0．1NTU，GOD去除率大于95％，氨氮去除率大于98％，满足中水回用标准．试验结果表明，用内径为2mm聚醚砜（PILS）中空纤维膜制作的RM—BR，长期稳定运行而未出现堵塞．增加跨膜压差（TMP）可以增加膜通量，当TMP超过适宜值后表现为通量与TMP无关的特性．提高膜面流速可以削弱污染层的形成，当超过适宜流速后也表现出通量与流速无关的特性．不同的污泥浓度（MESS）存在适宜的TMP和适宜膜面流速：当MLSS为2．2g／L、3．Ig／L、4．6g／L时，适宜的TMP为100kPa、80kPa、60kPa，膜面流速为0．6～0．9m／s．合适的反冲洗周期为40min，较佳的反冲洗程序为60s反洗＋15s正向冲洗．反冲洗和化学清洗可分别使膜的通量恢复至新膜的78％和89％．300h的运行表现出较好的稳定性．

RMBR of the oxygen- enriched aeration with membranes enhanced the wastewater treatment load. The resulted effluent had low turbidity and no detectable SS. The removals of COD and ammonia nitrogen were up to 95 % and 98 % respectively, which meets the quality standard for the reuse of civil wastewater. Experimental results demonstrate that the system was stable in a scheduled time without plug- up by using 2 mm diameter PES hollow fiber membranes. Increasing trans - membrane pressure （TMP） resulted in an increase in flux, and the flux was independent of TMP above a critical value. Increasing flow velocity reduced the formation of the fouling layer, which was independent of flow velocity once it reached a critical value. For every MLSS, there was a suitable TMP and flow velocity. At the MLSS of 2.2,3.1, and 4.6 g/L, the suitable TMPs were 100,80, and 60 kPa respectively, and the suitable velocity was between 0.6 and 0.9 m/s. The optimal back- flush period was 40 mln, and the optimal back - flush procedure was to back - flush for 60 s then forward - flush for 15 s with the influent valve open. The flux was restored to about 78% and 89% of its original flux when back - flush and chemical cleaning were applied. The system exhibited excellent stability during a 300 hours running.