Model And Experimental Study Of The Effect Of Organics On Phosphorus Removal By Ferric Iron

With the rapid development of national economy and the acceleration of-the industrialization,eutrophication has become a global environmental problem.In order to control eutrophication effectively,phosphorus should be controlled in water.Based on summing up the phosphorus removal technology in China and aboard,this thesis discussed the physicochemical process of phosphate removal by Fe(?)under the condition of existence of organics.The main research contents and results are as follows:1.The molecular model for citric acid on the removal of phosphate by Fe(?)in homogeneous environment was studied.It was found that removal performance of Fe(?)on phosphate largely upon pH and concentration of competing organic matters.The optimum range of pH value is from 6 to 8 to remove phosphate by Fe(?).When the solution is in a higher alkaline environment,the ability of phosphate removal by Fe(?)will be reduced with the increase of citric acid.The molecularly model based on mass balances was used to obtain the precipitation with empirical formula Fe1.6H2PO4(OH)3.8.2.The effect of SMP on the removal of phosphate by HFO in a two-phase system composed of HFO and SMP/phosphate under the conditions of environment pH was investigated.It was found that increasing pH and SMP concentration will inhibit the adsorption of HFO to phosphate.The equilibrium constant of surface complexation reaction between SMP and hydrous ferric oxide was obtained by inversion calculation as log10K= 15.1±0.11 in DLM model and log10K=12.1±0.5 in CD-MIJSIc model,which can improve the equilibriulm constants database of surface complexation models.3.The adsorption capacity of HFOon phosphate under different condition in multi-component systems which was composed of model organics,phosphate and HFO was studied.(1)Research ssuggested that pH value is the main factor affecting adsorption.The adsorption capacity on removing phosphate by HFO decreased with pH increased.(2)The effect of different concentration of organic matters on adsorption capacity was compared.It was found that high concentration of organic matters was not beneficial to the removal of phosphate.(3)The paper compare the effect of different organics on the removal of phosphate by HFO,then expounded the conclusion that different functional groups have different ability of competing surface charges with phosphate.The arranged sequence(from bigness to smallness)for the effect was acetic acid>oxalic acid>sulfosalicylic acid.