絮凝DAF中试工艺处理密云水库低温低浊水的影响因素

系统研究以硫酸铝和聚铝为絮凝剂时絮凝-DAF工艺中的水力学参数对除浊率的影响 .结果表明聚铝表现出了更优越的参数值 .在凝聚段 ,聚铝需要的高速混合时间为 15s,而硫酸铝则为 30s以上 ,2者对混合强度的要求为G=300～1000s^-1.聚铝的絮凝反应时间为 5.0min以上 ,硫酸铝为 7.5min以上 ,而且搅拌强度范围平均G值 =40～140s^-1;确定合适的总平均GT值≥2×10⁴.当应用聚铝为絮凝剂时 ,可以采用两级或三级等速搅拌 .对于仿MJ型的释放器 ,在实验的范围内释气压力为 2.5～3.3kg/cm² 时 ,5.0 %～8.3%的回流比较合适 .气浮接触区的水力条件和停留时间对絮凝气浮的除浊效果有较大的影响 .

Effective Factors of Flocculation-DAF Pilot Process Treating Water with Low Temperature and Low Turbidity from Miyun Reservoir

The hydraulic parameters in coagulation, flocculation and flotation units of DAF pilot process were systematically investigated when employing flocculants AS and PAC respectively. In general, the available parameters for PAC are more favorable in DAF process. For PAC as a flocculant during DAF run, the favorable coagulation rapid mixing time is 15 s, the flocculant mixing time is no less than 5 minutes. However for AS, the corresponding time values are greater than 30 s and more than 7.5 minutes respectively. The available coagulation mixing intensity is 300-1000 s-1. The available flocculation mixing intensity (average G) is 40-140 s-1, and the GT (average) value is greater than 2 x 10(4). Both equal-speed mixing and two or three stages mixing could provide slight better turbidity removal. For MJ model nozzle, the suitable recycle ratio is 5.0%-8.3% at dispersed pressure of 2.5-3.3 kg.cm2. The detention time and hydraulic intensity in contact zone of DAF tank have important effects on DAF turbidity removal.