Slag And Sludge Residue Geopolymer Cementitious Materials Preparation And Curing Effect Of Heavy Metals

Excess sludge is inevitable outcome of the sewage treatment process, and is to bring the serious problems of environmental pollution.With the astonishing output of sludge residue has been produced. Therefore, how to make sewage sludge reduced, stabilized, harmless and recycling, become the focus in the field of general environment of each country.In this experiment,slag and sludge including Other industrial waste were used.pretreatment methods and alkali-activated cementitious methods are applied in the study.A series of material test and characterization methods have been carried on the system analysis to optimize the best condition in experiment and results. The results of measuring the total amount, leaching abilities, speciation of heavy metals in residue and solidification of heavy metals are analyzed.In this study,wet method, dry method,ball mill method and no pretreatment are used to make sludge-slag geopolymer cementitious materials. Compared with orthogonal design experiment,it shows that when the Physical properties of sodium silicate is 1.3,the content of sludge residue is 20%, sodium silicate and the ratio of solid materials is 0.23, Physical and mechanical properties of geopolymer cementitious materials reach the maximum which are103.35 Mpa, 100.93 Mpa, 100.63 Mpa, 96.35 Mpa respectively. its mechanical performance indexes meets the national construction requirements and standards for construction materials.When the doping amount of sludge residue is 93%, the physical properties of the geopolymer cementitious materialscan still is up to the national minimum standards for building material.Because of the special polymer structures, it has more excellent mechanical properties. in the pretreatment, aluminate of sludge residue is easy to interact with sodium silicate, which make the mechanical properties of geopolymer cementitious materials better.By the means of modern testing instruments such as scanning electron microscopy(sem),infrared analysis, ICP,heavy metals such as Pb, Cr, Cu, zinc, Ni and its leaching of heavy metals in the polymer to change and curing effect are analyzed.The results shows that the effect of immobilization of heavy metals in polymer gelmaterials are stabilized. this is mainly due to the special structure of polymer and contains crystal structure, whish can make solidification of heavy metals in the polymer structure better and decrease the pollution of heavy metal.After the wet pretreatment, the effect of heavy metals to polymer immobilized is more obvious.its heavy metal leaching are Pb(0.00096 mg/L), Cr(0.13 mg/L), zinc(1.33 mg/L),Cu(0.23 mg/L), Ni(0.031 mg/L), Cd(0.035 mg/L),respectively.Which are far less than the national standard Pb(5 mg/L), Cr(3 mg/L), zinc(50 mg/L), Cu(50 mg/L), Ni(10 mg/L), Cd(0.3 mg/L). This is mainly due to the wet pretreatment sludge residue can make polymer reaction more thoroughly. As a result, it is a good method of heavy metals’ solidificationThe results show that the sludge residue, slag and other industrial wastes as raw materials could be successfully applied in building materials to polymer gel preparation material. its mechanical performance is good, and the structure of leaching of heavy metals in the sludge residue is immobilized effect. Furthermore, it is in accordance with national standards for building materials application,and its curing effect of heavy metals also meet the requirements of the national environmental pollution.