Solidification of hazardous waste pdf

E-mail: vojka. In situ stabilization are the well known methods for immobilization of contaminants, which prevents the spread of pollution through soil and groundwater. The most common method of in situ stabilization involves mixing contaminated soil or waste with cement or other materials that have similar chemical and physical properties fly ash The chemical and physical properties of cement or other materials includes the adsorption ability and ability to reducted mobility of hazardous and harmful component.

Solidification is applied to tailings ponds, where solids are mixed with additives, and as a result of mixing emerging geopolimeric matrix soil cement. After adjusting the mixing ratio, the mixture forms a solid monolithic layer.

The strength of the solidification process product has a direct influence on the efficiency of the process and can be increased by reducing the water ratio in mixture, increasing the solidification temperature or increasing of calcium chloride or Portland cement ratio as an additive.

Also, the efficiency of additives depending on the ratio and type of waste is shown. In such cases, the cement is used as a binding additive, because of water reaction with the cement produces the hydrated cement by chemically binding. Compression strength of at least 0.

Treatment of waste with inorganic pollutants content mostly. Inorganic materials contaminated with heavy metals are often categorized as hazardous due to the increased leaching potential of heavy metals leaching test and showing of the toxic characteristics toxicity test.

Treatment of waste by solidification or stabilization process resulting in a reducting of mobility of heavy metals and reducing the leaching potential of the inorganic material. After predtreatment, the material does not showing hazardous characteristics and can be disposed of nonhazardous waste landfill.

As an additive , in this case the cement is recommended because it reduces the mobility of the metal ions , forming less soluble metal hydroxide , carbonate or silicate. Furthermore, predtreatment may reduce the toxicity of metal by changing in the valence [5]. Treatment of waste with organic pollutants content mostly. Remediation of materials containing mainly organic pollutants is possible by applying a cement additive. In particular, it is recommended, if the waste is with high contains of free water, which enters the process of hydration, the cement material creating a highly integrated physical monolith.

Unadventage of cement is inefficient application on treatment of waste with a high content of fats and oils, when hydration process of cement is not possible. Cement particles are coated with oil or grease, which do not allow contact between cement and water. Some organic compounds influence on the curing time of the cement , whereby the whole process of solidification can be extended considerably. For these reasons, it is necessary to do a complete qualitative and quantitative analysis, before the selection of additives.

Also, the use of calcium carbonate occurs egzotrmne reactions during the process of hydration with simultaneously emission a significant amount of energy. Solidification and stabilization of heavy metals by hydrates of Portland cement is shown on figure 1.

Figure 1. Tabela 1. Test results of stabilization of hazardous wastes with different content of hazardous components using different additives are shown in table 2 [8].

Table 2. Adsorption onto hydrated iron III oxide abundant in the specimens accounted for the low mobility of arsenate. The metals should also be adsorbed, aided in most cases by low solubility at the high pH prevalent in lime and cement. The treated waste samples are from Bor area generated during mining activities with increasing content of copper 0.

Tabela 3. Factors affecting of the Stabilization and Solidification efficiency The proper choice of reagents. Stabilization of waste generated as a result of mining activity with a high content of the aqueous phase. The lime neutralization is the moust common method which is recommended for the stabilization of hazardous waste, particularly the inorganic waste with content of heavy metals, which is confirmed by researching of M.

In addition, in the process of solidification can occur at the surface of the grains, in the presence of silicon and aluminum, a liquid barrier calcium silicate gel or calcium-aluminate gel, thereby increasing the efficiency of the process [10]. Metal hydrolysis solubility curve is shown on figure 2, where also can see the influence of pH value on heavy metal mobility [5]. Figure 2. Cu, Hg, Ni, Pb, and Zn.

The compressive strengths of the specimens structural integrity Coz et al. When a specific waste were measured to determine the feasibility of using solid- is stabilized by means of a specific binding matrix, a study ified waste sludge as construction materials.

The com- is necessary to assess its potential to be used as building pressive strength values indicated that specimens could be material and therefore, assess the reuse of the waste instead potentially used as construction materials. The heavy metal of safe disposal Cioffi et al. Different processes and organic contents of the extracts of each specimen were exhibit different setting and curing reactions. Many processes can adjust the final strength and durability values by changing reagent mix ratios Conner and Hoeffner Talinli et al.

Talinli In the literature, several physical and chemical testing to compressive strength of the solidified materials. Satis- procedures have been identified.

The most common phys- factory results were obtained in the study. Leaching tests are used to study the leaching behavior of solidified wastes. The commonly used leaching tests from a chemical industry located in Gebze in the north- are categorized as: a extraction tests, b leach tests, and west of Turkey.

This industrial facility produces chemical c column leach tests. Two established extraction tests are materials to be used for metal finishing and surface treat- toxicity characteristics leaching procedure and extraction ment processes, as well as other chemicals for many dif- procedure EP toxicity test Chan et al. Examples can procedures as defined, and the hazard characteristics of the be listed as follows: evaluation of the effectiveness of the waste were determined based on both Turkish and USEPA stabilization and solidification of heavy metals from an regulations by means of leaching test methods DIN electroplating industry sludge Silva et al.

It was mixed with the sludge to solidify the waste. Figure 1 shows a work flow iour of chromium, cadmium, and aluminum that were for experimental studies. However, most of these studies waste as it was also shown in the experimental work flow.

The present A waste sludge sample was collected before the dewatering study was undertaken to help solidify and stabilize the processes, and Hach Digesdahl Digestion Apparatus was treatment sludge in different compositions in a C35 class of used to determine the total amount of metal in the sample.

The sta- The samples were digested by heating in the presence of bilization characteristics of the waste were evaluated from sulfuric acid and hydrogen peroxide.

In order to measure the total amount of metal and As lead, mercury, nickel, zinc, and chromium concen- the amount of soluble metals, atomic absorption spec- trations of the first leachate were all above these standards, trometer AAS was used.

As it Two procedures were used to specify leaching proper- can be seen according to extraction procedure toxicity test ties of untreated waste. DIN eluate and Ministry of Environment , are presented. EP extract were prepared according to these two proce- TOC concentration was measured for the characterization dures.

At this stage of the study, the treatment sludge was of the sludge TOC instrument, according to standard meth- dried before use. Leaching concentrations were compared to three different regulations to decide whether Portland Cement as a binder was mixed with the sludge to the samples could be experimentally determined as haz- solidify the waste and immobilize the pollutants.

Control ardous waste. Leaching concentrations of as a binder. Five different mixing ratios of waste to binder metals having specified standard were identified. DIN S4 leaching levels are stipulated for waste characterization before landfilling in the Turkish Hazardous Waste Control Regulations of c TS EN leaching levels are stipulated for waste characterization before landfilling in the Turkish Hazardous Waste Control Regulations of processes continued until concrete had a uniform appear- material.

After 24 h of shaking, the sample was filtered and ance. Specimens were mixed manually initially and after- analyzed. In the DIN S4 test leachates, the compo- ward the procedures were repeated by mixers. Mechanical properties The molded specimens were examined for the change in compressive strength at the end of 7, 28, 90 days curing time The compressive strength of all specimens in various ratios by compression test press. Three different curing times were and control was measured for 7, 28 and 90 days of curing applied to specimens to compare the compressive strength of periods.

Compressive strength values of the specimens the different curing time periods. In this test, concrete specimen was crushed to pass a 9. The extraction liquid was a mixture of 7 days deionized water and acetic acid; so the specified pH was 28 days achieved La Grega et al. The pH value of the 90 days extraction liquid was adjusted to 5. This test involved the addition of distilled Fig.