曝气量分配和填料填充率对MBBR氧转移效率的影响

Effect of Aeration Distribution and Carrier Filling Rate on Oxygen Transfer Efficiency of MBBR

针对曝气量分配方式及填料填充率对移动床生物膜反应器(MBBR)氧转移能力的影响问题,以青岛市某污水处理厂的MBBR单元为研究对象,以标准氧转移效率(αSOTE)为评价指标,通过正交试验确定了最优曝气量分配方式;在特定曝气系统阀门开启度工况下,采用尾气法对不同填料填充率(28%、33%、38%、43%)条件下好氧池沿程各测点处的αSOTE进行了连续72 h测试,最后通过整池平均αSOTE指标评价填料填充率对MBBR氧转移能力的影响。结果表明,在高长宽比(2.6∶1)MBBR反应器和高水流行进流速(36 m/h)条件下,当MBBR进水端、中部区域、出水端的曝气量分别采用中气量、低气量、高气量时,可在反应器内形成反向推流流态,避免填料堵塞;同时,在低填料填充率条件下可关闭穿孔曝气,降低曝气强度,节省能耗。随着填料填充率由43%逐渐降低至28%,MBBR整池平均αSOTE可由19.3%提高至30.2%。

To investigate the effect of aeration distribution and carrier filling rate on oxygen transfer capacity of moving bed biofilm reactor(MBBR), the standard oxygen transfer efficiency(αSOTE)was selected as the evaluation index, and the optimal aeration distribution mode of a MBBR unit in a wastewater treatment plant in Qingdao was determined by orthogonal experiment. Under the condition of specific valve opening of the aeration system, the αSOTE at each test point along the aerobic tank with different filling rates(28%, 33%, 38% and 43%) was tested by off-gas method for 72 hours. Finally, the effect of carrier filling rate on the oxygen transfer capacity of MBBR was evaluated by the average αSOTE of the whole tank. Under the condition of large aspect ratio(2.6∶1) of MBBR and high flow velocity(36 m/h), the reverse push flow state was formed in the reactor to avoid carrier blockage when the medium aeration rate, low aeration rate and high aeration rate was adopted respectively in the inlet, middle area and outlet of MBBR. In addition, the coarse-bubble aeration could be closed when the carrier filling rate was low, so as to reduce the aeration intensity and saving energy consumption. With the carrier filling rate gradually decreasing from 43% to 28%, the average αSOTE of the whole MBBR was increased from 19.3% to 30.2%.