岩性对砂石加工高浓度废水动态辐流沉降特性的影响

Effect of Rock Type on Dynamic Radial-flow Sedimentation Characteristics of High Concentration Wastewater from Processing Aggregate System of Hydropower Project

为探明岩性对水电工程砂石加工高浓度废水辐流池动态沉降特性的影响,以白鹤滩水电站砂石加工系统废水处理工程辐流池为例,基于动态沉降试验模型律,建立废水动态辐流沉降大比尺物理模型试验,分析以玄武岩和灰岩为料源的砂石骨料加工废水动态辐流沉降规律。试验表明:采用PAM和PAC联合投加可改善废水沉降浓缩效果,出水悬浮物去除率高于99%;玄武岩废水工况下,辐流池中部流速较高,固体颗粒呈现沿水深线性沉降浓缩的去除模式;灰岩废水工况下,辐流池底部流速较高,固体颗粒呈现先沿水深快速沉降,后在底层逐渐浓缩的去除模式;相较于灰岩废水,玄武岩废水自然沉降性能较差,辐流沉淀过程中对排泥速率控制的要求更高。研究成果可为水电工程绿色施工提供技术支撑。

The aim of this study is to investigate the influence of rock type on dynamic radial-flow sedimentation of high concentration wastewater produced from processing aggregate system for hydropower project.On the basis of the scaling law for high concentration wastewater, a large-scale physical model of the radial-flow sedimentation tank of Baihetan Hydropower Project was established as a prototype to elucidate the effect of basalt and limestone on dynamic radial-flow sedimentation characteristics.Experiment results manifested that combined addition of PAM and PAC could improve the settling and thickening effect of wastewater with the removal rate of suspended substance in treated water exceeding 99%.For basalt wastewater, higher velocity was observed in the middle layer of radial-flow sedimentation tank, and solid particles presented linear sedimentation along water depth;for limestone wastewater, higher velocity was observed in the bottom layer of radial-flow sedimentation tank, and solid particles settled rapidly along water depth in the first phase, and then gradually concentrated in the bottom layer.Compared with limestone wastewater, basalt wastewater is of inferior natural sedimentation performance, posing higher control requirement for sludge discharge rate during radial-flow sedimentation.The research findings offer technical support for green construction of hydropower projects.