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IntroductionAn environmental impact assessment (EIA) before embarking on any project is a useful tool to reduce the potential effects of each project, including landfill, if possible. The main objective of this study was to assess the environmental impact of the current municipal solid waste disposal site of Gonabad by using the Iranian Leopold matrix method.MethodsThis cross-sectional study was conducted to assess the environmental impacts of a landfill site in Gonabad in 2015 by an Iranian matrix (modified Leopold matrix). This study was conducted based on field visits of the landfill, and collected information from various sources and analyzing and comparing between five available options, including the continuation of the current disposal practices, construction of new sanitary landfills, recycling plans, composting, and incineration plants was examined. The best option was proposed to replace the existing landfill.ResultsThe current approach has a score of 2.35, the construction of new sanitary landfill has a score of 1.59, a score of 1.57 for the compost plant, and recycling and incineration plant, respectively, have scores of 1.68 and 2.3.ConclusionResults showed that continuation of the current method of disposal, due to severe environmental damage and health problems, is rejected. A compost plant with the lowest negative score is the best option for the waste disposal site of Gonabad City and has priority over the other four options.

a b s t r a c tAs-prepared activated carbons (ACs) were utilized as an adsorbent for removal of Cr (VI) ions from aqueous solution. The effects of different operating parameters such as adsorbent dosage, pH, contact time, initial Cr (VI) concentration and temperature were conducted by batch experiments. According to experimental results, the equilibrium time, the optimum pH, and adsorbent dosage were found 120 min, pH 3, 5 g/l, respectively, with 2.5 g H 3 PO 4 of carbonized sample and post-treatment step by refluxing with HCl and NaOH and autoclaved with HF (arAC) with the BET surface area of 472 mg/g. The equilibrium adsorption data were fitted well by Langmuir and Freundlich adsorption model with a monolayer maximum adsorption capacity of 12.8 mg/g. The rate of Cr (VI) adsorption onto the AC was reasonably explained by the pseudo-second-order kinetic model. In addition, the thermodynamic parameters of the adsorption process such as standard Gibb's free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) were evaluated. In a fixed-bed column adsorption, the effects of bed height, flow rate and initial ion concentration on the breakthrough curve were investigated, on which the predictions were found to be satisfactory both by the Yan models. The results showed that a maximum of adsorption capacity was 94.54 mg.g -1 by the sample of the arAC. Finally, we found out the sewage sludge-based AC was an efficient low-cost adsorbent for Cr (VI) removal from electroplating industrial wastewater.

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