Structure Design And Experimental Research Of Composite Industrial Waste Residue-based Fiber Filter

Phosphorus is the main cause and the main limiting factor for water eutrophication.Controlling the external input of phosphorus in the water body is an important means to effectively control and prevent the eutrophication of the water body for a long time,and the discharge of the effluent from the urban sewage treatment plant is one of the main external input of phosphorus in the water body.In recent years,the discharge standard of sewage treatment plant has been improved continuously.In some areas,the effluent of sewage treatment plant is required to reach the class IV standard of surface water.It can be seen that the national limit on the total phosphorus in the effluent of sewage plants is becoming more and more strict,and the demand for raising the standard of total phosphorus in the first-class B tail water of the sewage treatment plant to class IV surface water is increasingly urgent.Based on this thesis,the industrial waste residue-based fibers with good phosphorus removal performance,which were prepared by wet spinning with modified steel slag,zeolite,fly ash and cellulose acetate in the previous study,were optimized,and the optimal concentration and type of plasticizer were selected to improve the tensile strength and softness of the fibers and their preparation speed.On this basis,the influencing factors of the phosphorus removal efficiency of the composite fiber were studied,and the composite fiber was used as the filter material of the new fiber filter which was independently developed.The optimal process parameters were determined by comparing the effects of different fiber dosage,different hydraulic retention time and different regeneration liquid of the filter material on the phosphorus removal efficiency of the filter,and the operation efficiency of the filter under the optimal process parameters was studied.The results show that the phosphorus concentration in the effluent of the filter can be steadily reduced to less than 0.3mg/l,which meets the phosphorus concentration standard of class IV in the national environmental quality standard for surface water（GB 3838-2002）.The main research contents are as follows:（1）In the preparation process of industrial waste residue-based fiber,the effect of two different plasticizers,polyethylene glycol 600 and tributyl citrate,on the tensile strength of the fiber was compared with that of basalt fiber in the previous study.The results show that the tensile strength of the composite fiber is the best when polyethylene glycol 600 is used as plasticizer,which is 1.43 times of that when basalt fiber is used as reinforcement base material.The speed of fiber preparation was optimized.The maximum pushing speed of spinning solution was increased to1.6mm/min,and the winding speed of fiber was increased to 2.04m/min.The speed of fiber preparation was 1.86 times of that before optimization.（2）The isotherm adsorption experiment of industrial waste residue-based fiber shows that the isotherm equation of phosphorus adsorption of composite fiber accords with Langmuir equation.The effects of dosage,p H,inorganic anions SO₄^2-,Cl^-,NO₃^-and CO₃^2-on phosphorus removal were studied.The results show that when the initial phosphorus concentration is fixed,the phosphorus removal rate is positively correlated with the fiber dosage,and the phosphorus removal rate per unit mass fiber is negatively correlated with the fiber dosage;the p H has a more obvious effect on the phosphorus removal effect of the composite fiber,and the phosphorus removal effect of the fiber under acid or alkaline conditions is better than that under neutral conditions,but the fiber also has a better phosphorus removal effect under neutral conditions The results show that the industrial waste fiber has good acid-base adaptability,and the inorganic anion CO₃^2-has obvious inhibition on the removal of phosphorus,and the other anions have no obvious effect.（3）The traditional pressure plate fiber filter was optimized,and the defects of its movable orifice plate are easy to get stuck,and the pores of the orifice plate are easy to be blocked,and its backwashing method and filter material component form were improved.（4）The effect of fiber dosage and HRT on the phosphorus concentration in the effluent of the filter and the effect of different concentration of regeneration solution on the regeneration effect of the fiber filter material were studied.Under different operating conditions,the operation stability of the filter under three different initial phosphorus concentrations（3mg/L,1.5mg/l,0.5mg/L）for 60 days was studied.According to the operation results,fiber dosage of 2.5kg and the hydraulic retention time of 4h,3h and 3h were selected as the the optimal operation parameters of the filter with initial phosphorus concentration of 3mg/L,1.5mg/l and 0.5mg/l respectively.After using 0.1mol/l HCl solution to regenerate the fiber for three times,the phosphorus removal per unit mass of the fiber decreased only 12.32%,and the regeneration effect was good.In the 60 days of operation,the phosphorus concentration in the effluent of three groups of filters with different initial phosphorus concentration was always stable below 0.5mg/l.When the initial phosphorus concentration was 3mg/L,the effluent phosphorus concentration of the filter can be stable below 0.3mg/l after two times of backwashing;when the initial phosphorus concentration was 1.5mg/l,the effluent phosphorus concentration of the filter can be stable below 0.3mg/l after one time of backwashing;when the initial phosphorus concentration was 0.5mg/l,the phosphorus concentration in the effluent without backwashing remained stable at about 0.2mg/l within 60 days.Within 60 days,the p H value of the effluent was higher than that of the raw water,but it did not exceed the limit value of p H value in the environmental quality standard for surface water（GB3838-2002）.The results of heavy metal dissolution test show that the fiber filter material will not increase the concentration of heavy metal ions in the effluent,and will not cause secondary pollution.