污泥回流对平流式沉淀池去除率的影响分析

针对目前的沉淀理论没有考虑回流污泥量将影响颗粒去除效率这一问题,在深向混合沉淀理论的基础上,得出了考虑回流比的非理想沉淀模型.根据所得模型分析了在平流沉淀池中吸泥机带走的污泥回流量对颗粒沉降的影响.并以某污水悬浮物的剩余量与沉速关系曲线为例进行分析.结果表明,在不考虑污泥回流的情况下,颗粒的去除率为72.8%;考虑污泥回流时,当回流比由0.5变化到3.0时,颗粒的去除率则由71.1%递减到50.9%,均小于不考虑污泥回流时的去除率,且回流比为3.0时,颗粒的去除率为50.9%,相对于未考虑回流污泥时的去除率降低了30%.由此可见,污泥回流量使悬浮颗粒的去除率小于无回流量时的去除率,且随着回流比的增大颗粒沉降效率将显著减小.

Analysis of Effect of Sludge Recirculation on Setting Efficiency in Horizontal Sedimentation Tank

The problem that the present sediment theory does not consider sludge recirculation effect on the efficiency of particle settling is studied. Based on the longitudinal mixing settling theory, an imperfect sediment model that takes reflux ratio in consideration is built. According to the established model, the study analyzes the effect of sludge recirculation taken by suction dredge on particle setting, in horizontal sedimentation tank. Specifically, the relation between overplus of sewerage suspension and sedimentation rate was chosen as an example. Shown as a result, when sludge recirculation is not taken in consideration, efficiency of particle settling is 72.8%. However, when sludge recirculation increases from 0.5 to 3.0, efficiency of particle settling decreases from 71.1% to 50.9%, which is smaller than efficiency of particle settling without recirculation; and when sludge recirculation is 3.0, efficiency of particle settling is 50.9%, which is approximately 30% less than efficiency of particle settling without recirculation. So, sludge recirculation make efficiency of particle settling is smaller than efficiency of particle settling without recirculation, and the efficiency of particle settling reduces with the increase of reflux ratio.