Introduction: Modeling energy demand in different energy consuming sectors is a crucial measure for effective management of the energy sector and appropriate policies to increase productivity. The rising importance of energy resources in economic development is evident. Sustainable energy use is crucial for environmental protection and social progress. Understanding the factors affecting energy consumption is essential for effective energy management. Therefore, the purpose of the current study is to investigate the impact of environmental factors on household electricity consumption in Yazd city. Materials and Methods: In the present research, various environmental factors affecting electricity consumption, including air pollution, air temperature in homes, ground surface temperature, and green space were investigated. The effects of these factors on electricity consumption of subscribers were investigated with ANN and  apriori methods. Results: Among the environmental factors, the distance to the regional park, the area of the park, and the amount of vegetation at a distance of 300m have the greatest impact, respectively, and the average summer air temperature, the amount of vegetation at a radius of 500 m, the distance from the local park, and the average summer NDVI have had the smallest effect. Unlike neural network methods, apriori presents relationships between parameters affecting electricity consumption transparently in the form of rules. Conclusion: It's used to identify the most frequently occurring elements and meaningful associations in a dataset. Greenspace can be a mitigation strateegy for reduction of energy consumption.

Background and objective: Compost is beneficial for conditioning the structure and nutrient content of soil. Toxic metals are the most important contaminants that can enter the food chain through the compost products and affect human health. The aim of this study was to assess the arsenic, mercury, cadmium, and lead levels in six brands of vermicompost produced from the organic solid wastes in Tehran and to compare the amounts with the international and national standard levels.Materials and Methods: This was a descriptive - analytical study in which samples of six brands of vermicompost products were randomly selected from the distribution centers in Tehran, and from each brand four samples were prepared (24 samples). Then the samples were extracted using the TCLP (Toxicity Characteristic Leaching Procedure) method and after filtration the metal concentrations were measured by Inductively Coupled Plasma (ICP). All data were analyzed using Excel software.Results: The means and standard deviations of the toxic metals concentrations (arsenic, mercury, cadmium, and lead) in the collected samples of each brand were reported in terms of mg/kg. The maximum concentrations of these toxic metals were 7.45, 0.15, 0.19, and 79.95 mg/kg, respectively.Conclusion: The results indicated that the levels of toxic metals in the vermicompost samples derived from the municipal solid waste in Tehran were lower than the permissible limits of the national and international standards.

One of the suggested techniques to prevent the spread of contaminants in the soil is cement-based stabilization/solidification. The production of hydration products and the attainment of an alkaline pH are the two primary processes in this method. In natural conditions, contaminants enter the soil simultaneously and in combination with each other. The simultaneous presence of organic and heavy metal contaminants alters how the soil-cement system interacts with each contaminant. The objective of this study is to compare the desorption and retention amounts of cadmium and phenol separately and simultaneously in cement-based stabilization/solidification. In this context, the TCLP test has been used to assess the desorption amounts of phenol and cadmium, as well as their retention capacity in single and combined systems. An X-ray diffraction test was also carried out to examine the microstructure of the stabilization/solidification process. The results indicate that the retention percentage of phenol in the presence of cadmium did not differ much compared to the single system, while the amount of cadmium retention decreased in the presence of phenol. In a combined system, the simultaneous presence of phenol and cadmium causes a reduction in the intensity of the C-S-H peak compared to single systems. However, the presence of cadmium had a greater effect on reducing the intensity of the C-S-H peak than phenol. Furthermore, in the presence of cadmium, the amount of phenol extracted during the TCLP test has increased compared to the single system.

The presence of heavy metal contaminants in clays causes changes in soil properties, which increases the risk of contaminant transport into the clay layer. Various techniques have been developed recently to remediate contaminated soil. These methods include electrokinetics, biological treatment, and immobilization. Among them, cement-based stabilization/solidification technique is very common. Generally, cement-based systems are frequently used because of their affordability and great durability. This method uses the two mechanisms of chemical stabilization and physical solidification to retain heavy metals and decrease the mobility of contaminants. Even though several researches have been performed to address the different aspects of cement-based solidification/stabilization, there has been a lack of research on the stabilization/solidification of heavy metals in the presence of two different heavy metal ions. Therefore, the objective of this study is to determine to what extent the pH variations affect lead and cadmium retention and release in single and double-component cement-based stabilization/solidification systems. To accomplish the aforementioned objective, first, the retention capacity of lead and cadmium, in cement-based S/S of contaminated bentonite in single and double-component heavy metal systems is investigated. The effect of pH on the stabilization/solidification process was determined by conducting a series of XRD tests in order to investigate and differentiate the stabilization and solidification mechanisms. In the next step, the amount of released cadmium and lead ions during the TCLP test was determined in single and double-component systems in order to investigate the effect of pH and the simultaneous presence of lead and cadmium in the release of these heavy metals. According to the achieved results, the maximum retention capacities of lead and cadmium occur in the pH ranges of 8.5 to 11 and 10 to 12, respectively. Furthermore, retention in the double-component system is always lower than that of the single-component system, assuming a similar initial concentration. In addition, XRD results illustrate that the intensity of the peaks of cadmium and lead chemical compounds has increased for the samples their pHs take place in the safe zones. This indicates an increase in the contribution of the stabilization mechanism. According to the results of this paper, at a similar contaminant concentration, the intensity of the C-S-H peak increases with an increase in cement percentages. This indicates progress in the contribution of the solidification mechanism in the retention of heavy metals. Still, the release of these heavy metals is always lower than the maximum allowable value reported by the US EPA in the above-mentioned pH ranges. Moreover, the results of this research show that the amount of released cadmium and lead in the double-component system is more than that of the single-component system, assuming similar initial concentrations. Based on the definition of the safe zone, in the defined pH range, the contaminant is retained during the TCLP test mainly by chemical stabilization (precipitation). In fact, in the above range, an increase in the amount of cement has not shown a significant effect on the amount of heavy metal desorption. This finding is supported by the results of retention tests.

Mining is an upstream industry in the supply of industrial raw materials. The large volume of mine tailings as well as the considerable concentration of toxic pollutants, resulted from mining activities, cause irreparable damage to the surrounding environment. The leakage of toxic elements from the mine tailings to the environment is considered as a crucial issue. Therefore, the management of mine tailings is an important approach to reduce environmental damage. The reuse of mine tailings in concrete industry is considered as one of the main management techniques to reduce their probable adverse effects. In this study, the tailings of Sungun copper mine were collected to investigate their applicability in concrete construction instead of fine-grained materials. The results revealed that the concentrations of copper, arsenic, lead, chromium, cobalt, and nickel in copper mine tailings were higher than the environmental criteria but less than the amounts required for economic recovery. Thus, tailings with a grain size of less than 297 μ m were used in the construction of two series of concrete samples to replace 50 and 100% of the fine-grained part of the concrete. Moreover, some experiments including concrete slip, compressive strength, resistance to chlorine penetration, and TCLP were performed to ensure the applicability of copper mine tailings in concrete construction. In samples where copper tailings replaced 50 and 100% of fine-grained materials, the 28-day compressive strength was 32 and 41 MPa, respectively. The compressive strength increased with increasing replacement rate. According to the results, the highest leachate rates of copper, chromium, lead, zinc, cobalt, cadmium, and arsenic were 21, 2. 8, 3. 9, 106, 75, 0. 39, and 0. 82 mg/L, respectively. Thus, it could be concluded that if copper tailings are used in concrete, the amount of heavy metals leachate will be reduced to values below the environmental criteria level.

Cement-based stabilization/solidification is a commonly used method to prevent the transportation of heavy metal ions in soils. The main objective of this paper is to investigate the controlling mechanisms in cement-based stabilization/solidification of Pb ion-contaminated bentonite under two different curing conditions: closed and open systems. In an open system, the stabilized/solidified sample continues to have access to free water, while in a closed system, the stabilized/solidified sample is prevented from accessing any external water after initial mixing. To achieve this objective, a series of geo-environmental experiments, including pH, solubility measurements, TCLP, and XRD, were performed. In the first step, the bentonite sample was contaminated with 100 cmol/kg-soil of lead nitrate. After achieving equilibrium, the contaminated sample was stabilized/solidified with 15% cement. The results indicate that when 15% cement is applied to the contaminated bentonite, the pH ranges from 10.5 to 11.5, which is a safe domain for lead precipitation. In other words, the minimum required percentage of cement for stabilization/solidification is the quantity in which the pH of the system is in the necessary range for heavy metal precipitation. This quantity is generally a function of the type and concentration of the heavy metal contaminant. According to the experimental results of this research, the method of curing does not have a noticeable impact on the stabilization process of stabilized/solidified contaminated bentonite. However, the XRD results show that more pozzolanic components have formed in the closed system. Therefore, the achievement of EPA criteria for TCLP experiments in cured samples in the closed system is attributed to the more significant progress in pozzolanic interaction and more formation of C-S-H and C-A-S-H components at 28 days for cured samples under closed conditions.

The solidification/stabilization of bentonite and heavy metals is among the conventional methods in geo-environmental projects. Among the various methods used for the solidification/stabilization process, cement-based systems are widely used due to their relatively low cost, availability, and environmental compatibility. Cement-based solidification/stabilization technology is an attractive option for managing heavy metal contaminants and facilitating final transportation and containment, thereby reducing contaminant emissions to the environment. The efficiency of solidification/stabilization technology can be improved through certain modifications. The objective of this paper is to determine the effect of substituting calcium carbonate on improving the solidification/stabilization process of bentonite and heavy metals towards reducing cement consumption. To achieve this goal, samples of bentonite containing 100 cmol/kg-soil concentration of lead nitrate with different compositions of cement and calcium carbonate were solidified/stabilized. To determine the appropriate concentration of added contamination to the soil, a series of tests for heavy metal retention using the soil suspension equilibrium method, based on EPA standards, has been conducted. These tests were performed on bentonite suspensions at heavy metal lead concentrations ranging from 0 to 250 cmol/kg-soil. In EN197 standard, two types of Portland limestone cement are introduced with the names II/A-L and II/B-L, containing 6 to 20 percent and 21 to 35 percent calcium carbonate, respectively (EN197-1, 2000). Based on this, in the present study, up to 25 percent by weight of calcium carbonate is used as a substitute for ordinary Portland cement, and the combination of cement and calcium carbonate as a binder is used. The mechanism of contaminant retention was evaluated through XRD, TCLP, pH, and UCS tests. In this study, the amount of immobility of heavy metals after stabilization and solidification process using the Toxicity Characteristic Leaching Procedure (TCLP) based on EPA-1311 method has been evaluated. In the first stage of the aforementioned experiment, the solidified/stabilized contaminated sample was adjusted to pH 8.2 with a 0.1 molar hydrochloric acid solution and prepared as a suspension with an S:W ratio (solid:water) of 1:20. All suspensions were continuously shaken for 18 hours using a mechanical shaker, and after measuring the pH of the samples and centrifuging them, the liquid phase was separated and the contaminant concentration was measured using a GBC932 AB Plus atomic absorption spectrophotometer. Unconfined compressive strength (UCS) can be used as a criterion for assessing hydration reaction progress. In this study, samples were subjected to curing for 7 and 28 days in a closed system and placed in a humid chamber at 23 degrees Celsius and 95% humidity according to ASTM D1633-17 standard, with a uniform density of 1.85 g/cm³ for testing unconfined compressive strength. Furthermore, X-ray diffraction (XRD) analysis was utilized to investigate the microstructure of the samples and the progress of the cement hydration process and its interaction with contaminated clay minerals. According to the results of this study, replacing 15% calcium carbonate instead of cement preserves the necessary conditions for the establishment of stabilization and solidification mechanisms. For instance, for a sample containing 1.4% optimum moisture, the desorption amount of lead ions in the TCLP test is equal to 2 milligrams per liter, and the uniaxial resistance of the sample is equal to 1.45 MPa, meeting both EPA standards. In fact, the achieved results indicate that substituting up to 15% calcium carbonate instead of ordinary Portland cement not only reduces cement consumption but also improves the contaminant retention capability in the cementitious solidification process. The reason for the improvement in these conditions is attributed to the simultaneous role of calcium carbonate filling and nucleation alongside the increase in the range of carbonate compound sedimentation.