Background and Objective: Daily 7500 tons of municipal solid waste generated in Tehran and after processing, 4000 tons of them remain as rejected waste. Reuse of waste to conserve resources and reduce environmental pollution is necessary. The objective of this study was
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Background and Objective: Daily 7500 tons of municipal solid waste generated in Tehran and after processing, 4000 tons of them remain as rejected waste. Reuse of waste to conserve resources and reduce environmental pollution is necessary. The objective of this study was to investigate the technical and economic possibilities of using Tehran rejected waste in cement kilns. Method: The amount of rejected waste was askesd from the Waste Management Organization and their heat value was computed using the Dulong Formula. Then, physical and chemical characteristics of the rejected waste were computed using ultimate analysis. Finally, the cost of producing 1 ton of clinker using gas, Mazut and waste fuel, as well as the cost saving by using waste in kiln No. 8 of the Tehran cement factory were calculated. Findings: Tehran rejected waste contains chemical formulas of C71H107O32NS0.07, 24.72% moisture, 21% ash content and 21.4-23.6 MJ/kg heating value. Therefore, we can produce 3613.54 tons/day of waste fuel with a heat value of 19.63 MJ/kg and 20% moisture content. Also, replacement of 10% of the heating value used in kiln NO. 8 of the Tehran cement factory with waste instead of Mazut will result in a 4.16 billion Rial annual revenue and 282.6 million Rial saving in the cost of waste landfilling. Conclusion: The heating value and sulfur content of Tehran rejected waste meet the requirements of alternative fuel; however, reduction of ash, moisture content and size of waste, as well as increase of heating value of the rejected waste is necessary.
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