| At present, the treatment methods of waste water containing zinc mainlyinclude coagulation, sulfiding precipitation, ferrite, electrolysis, exchange resin,adsorption and etc. The first three kinds of methods are industrialized with goodeffect. But it is difficult to dispose the wastes produced by adding lots ofchemicals in the separation process. It is not applicable for disposing lowconcentration waste water with electrolysis. The cost and investment is too highusing exchange resin and adsorption. Also zinc is a amphoteric element andexisting in the form of Zn2</sup>, Zn(OH)2 and ZnO22- in the solution, which Zn2+ andZnO22- is ion state, Zn(OH)2 is coagulation state. Therefore, the above-mentionedmethods is very difficult to separate zinc from waste water, how to select oneeconomic and effective separation methods becomes the technological difficultproblem of dealing with waste water containing zinc and environmental protection.Foam separation becomes a preferred method to solve this problem with highremoval efficiency in the low concentration and continuous operation.In this paper, trace of zinc in the water is separated by the use of dissolve gasfoam separation equipment of trough and column. The influences of types andconcentration of surfactant, pH value, the pressure of solute gas, solute gas-waterflux, input flux and the mass concentration of aluminum sulfate were reviewed.When the concentration of zinc ion is 10mg·L-1, the concentration AOS of is15mg·L-1, pH value is 11, the pressure of solute gas is 0.24～0.26MPa, solutegas-water flux is 250L·h-1, input flux is 50～70L·h-1, the mass concentration ofaluminum sulfate is 25～75mg·L-1, the removal efficiency is 98.37%.According to the similar physical behaviors of foam separation process andchemical reaction process, the equivalent chemical reaction constant wasintroduced, then the macroscopical dynamics of foam separation zinc ion from water was studied. The result indicated that that the process of foam separationcould be regarded as first order reaction, which equivalent speed constant isk=0.448 min-1. By measuring and analyzing the distribution of residence time,the average residence time is tm=10.29min, variance isσθ2=0.578. Thedistribution density function of residence time is confirmed combined with therelevant experiments. The influence factors about the foam separation processremoval efficiency of fluid flowing are studied. The mathematic model of thisprocess was analysed and discussed combined with the residence time distributionfunction and variance.
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