Study On The Granulation Of Aged Refuse And Its Adsorption Characteristics Toward Zinc

Nowadays, with the speed of urbanization increasing in our country, the disposal of municipal solid waste (MSW) has become a serious problem. The characteristics of high moisture content and low heat value of MSW make sanitary landfill have been the main treatment. While large areas of land resources are needed as landfill site due to the more living waste. Therefore, the larger capacity and longer service life of the landfill have been a significant way to solve the question. What’s more, the mining of aged refuse is the key to this method.Aged refuse comes from the degradation of a certain period of time in the landfill, with excellent physical and chemical property, such as porous structure, huge surface area, good cation exchange capacity, good hydraulic conductivity and permeability, can provide good adsorption exchange conditions. Previous study showed than the aged refuse was rich in organic matter and nitrogen, phosphorus and other nutrients, but also contain heavy metals and other pollutants. The particle size distribution was polarized with the trend, the small particle size (0-90μm) content was20%or more, which is more easily to accumulate heavy metals and other pollutants. There is poor permeable, easy caking and other defects in the application process, to some extent become bottlenecks to its utilizations.Because the disadvantages described above may cause the environmental risks at its utilizations. Therefore, granulated0-90μm aged refuse, the preparation conditions and adsorption characteristics of Zn on two aged refuse was studied. Study the granulation process and adsorption on heavy metal, provide a theoretical basis and technical reference to aged refuse more effective resource.The granulation experiment showed that when sodium alginate and aged refuse were1g and2g, respectively, immobilized time24h, the preparation condition was best. The sample have characteristics of uniform particle size, roughness surface, internal porous.Adsorption kinetics experiments showed that:the initial adsorption rate of granulated aged refuse reduced, but the adsorption capacity increased significantly when equilibrium was reached (granulated aged refuse was7.40mg/g,0-90μm aged refuse was4.80mg/g). The sorption process on two aged refuse followed pseudo-second-order kinetics very well. The adsorption behavior of Zn2+may be affected by the rate of reaction and diffusion factor.The adsorption isotherms of Zn2+showed that:in a certain concentration conditions, adsorption capacity of Zn2+on granulated aged refuse was significantly higher than0-90μm aged refuse. The experimental data was compliance with the Langmuir adsorption isotherm best. The inherent adsorption capacity of0-90μm aged refuse slightly larger than granulated aged refuse. The adsorption mechanism is dominated by physical adsorption.Thermodynamics data showed that both of the adsorption on two aged refuse were spontaneous, entropy and endothermic process. The temperature rise was conducive to the adsorption, adsorption of Zn2+on0-90μm aged refuse was lower than granulated aged refuse under different temperature conditions, but reaction enthalpy and entropy changes were higher than the latter. Thus the adsorption of Zn2+on0-90μm aged refuse was more activity.The effect of pH on adsorption of Zn2+by two aged refuse was studied, and the data showed that the adsorption capacity of was higher than0-90μm aged refuse in different pH environment. The best adsorption condition of0-90μm aged refuse was pH5-6, while granulated aged refuse was pH7.