Research On Treatment And Recycle Technique Of Wastewater Drained From Iron And Steel Works

This paper analyse the characteristics of wastewater drained from Xiang-tang iron and steel works. Static laboratory test shows that the treatment by lime-sodium carbonate and composite coagulant chemical precipitation method can reach the requirement of recycle; the cost is under control.Based on hydrodynamics analysis, the new remarkable effective flocculation model reactor is designed according to the theory of reactor and Micro-Vortex of flocculation kinetics. Several suitable disturb-flowing device is designed for it meanwhile.The dynamic experiment using the new flocculation model provided optimal process and valuable parameters for the wastewater recycle projector of Xiang-tang iron and steel works. The results show that a suitable combination process and its condition as follows: Lime-sodium PFS-PAM↓↓Wastewater—→removal of hardness and alkalinity—→mechanical/hydraulic mixing—→flocculating—→precipitatingDosage of medicament per ton(wastewater) as follow: lime ( 90% for industry),18.5～27.75g; sodium carbonate(99% for industry),39.75;PFS,3g; H₂SO₄(98%),4.752g;PAM(molecular weight 500～1800 ten thousand),0.5～2.0g; total cost of medicament:0.07～0.10yuan per ton(wastewater).The best waterpower condition as follow: GT 32241.6(mixing),2688.1(flocculation),Re 26930(mixing),3850(flocculation),precipitating time 75min.This paper conduct preliminary study on model test, and compare its flocculation effectiveness and dosage of many kinds of flocculants. Results show that the flocculation effectiveness on mixing and reaction in model is same to that in jar. meanwhile, the model test can save flocculants and cost, on the same condition that jar test can reach 90% removal rate ,this model test's dosage of flocculants is same to it.When we judge of running of the flocculation model by reactor theory, it is a feasible way to analyse real model's axial back-mixing and its departure from ideal model by residence time distributions and the dispersion model. New model reactor's D/UL(1/Pe) is 0.08～0.1,that show it is close to plug flow, and axial back-mixing is puniness.