Study On Sewage Treatment System Of Medium And Small Stone Enterprises And Design Of Sedimentation Tank

In order to reduce the wastage of the bit tool and improve the processing quality,a large amount of water is needed during the stone processing,and a large amount of sewage is produced.The wastewater contains high concentrations of stone powder and chemical additives such as coolant.Our country provided that stone processing enterprises must be equpped with sewage purification and recycling equipment,in order to realize the reuse of stone waste water,save water resources and protect the environment.This topic combined with the present situation of small and medium sized stone enterprises,studied the physical and chemical characteristics of stone wastewater,according to the most important precipitation in the treatment of stone wastewater,through the combination of experiment and numerical simulation.this topic can improve the present situation of the stone wastewater treatment technology,in line with current trends.The pollutant composition of stone processing wastewater was analyzed,Investigated and measured of a number of stone processing enterprises sewage SS,turbidity and particle size distribution,got preliminary understanding of several important physical and chemical properties of stone wastewater.Through beaker flocculation test and cylinder sedimentation test,finding the addition amount of flocculant in different SS.The relationship between PAC and SS was y=3.482e-14x3 471+194.6,the relationship between PAM and SS was y=6.964e-14x3.471+3.929.The final treatment results are not related to the initial concentration of the wastewater.Under the optimum flocculant dosage,The settlement velocity of different SS stone sewage is between 3.8mm/min and 7.8mm/min,after settling for 4 hours,the sludge volume is about 16%～17%of total sewage volume.The internal flow field of sedimentation tank was studied by using CFD sofware,the structure and size are optimized.Using RNG k-ε multiphase flow model,the movement law of the limestone powder,the turbulent structure and the concentration distribution of the powder particles were carried out,the influence of the structure and size of the sedimentation tank on the settlement is revealed from the microscopic point of view.For 10 saw scale stone enterprises,when the distance between the reflector and the center tube is 0.2m,the reflective plate angle is 145°,the pool depth is 5.6m,sedimentation tank get the best settlement effect.The sedimentation efficiency of the sedimentation tank after optimization is 3.4%higher than that of the experimental method,and the depth of the sedimentation tank after optimization is reduced by about 6.7%.