Abstract: 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.

Key words: hydropower project, aggregate system, rock type, wastewater of high concentration, dynamic radial flow sedimentation, physical model