ارزيابي سناريوهاي چرخه حيات در استراتژي هاي مديريت پسماند شهر ماهدشت

Life Cycle Assessment (LCA) of Municipal Waste Management Strategies in Mahdasht City

در سيستم مديريت مواد زايد جامد، با توجه به ميزان توليد و تركيب پسماند، گزينه هاي مختلفي براي مديريت آن وجود داردكه علاوه بر هزينه‌هاي اقتصادي، بار محيط‌ زيستي مختلفي دربردارند. در اين مقاله به بررسي توليد و انتشار گازهاي گلخانه اي، مه دود فتوشيميايي و خروجي هاي سمي در گزينه‌هاي مديريتي مختلف پسماند شهري در شهر ماهدشت استان البرز به روش ارزيابي چرخه حيات(LCA) با كاربرد نرم افزار IWM پرداخته شده است. به اين منظور، ٢ سناريو شامل (١) انتقال كامل و مستقيم پسماند به محل دفن و (٢) انتقال ٧٦% پسماند به محل دفن(٢٠% كمپوست و ٤% بازيافت) در نظر گرفته شد. داده هاي مورد نيازسياهه نويسي چرخه حيات با بررسي منابع و طرح‌هاي پژوهشي پايان‌يافته، تهيه پرسش‌نامه و تكميل آن به وسيله پرسنل و نيز كار صحرايي جمع‌آوري شد. سپس، نتايج به دست آمده از سياهه نويسي به ۵ طبقه اثر شامل مصرف انرژي، گازهاي گلخانه اي، گازهاي اسيدي، مه دود فتوشيميايي و خروجي هاي سمي تخصيص داده شد .از نقطه نظر محيط زيستي، نتايج اين مطالعه نشان داد كه كمپوست كردن به عنوان يكي ازگزينه هاي مديريتي و نيز عمليات بازيافت، نقش مهمي در كاهش بار آلاينده ها و نيز مصرف انرژي ناشي از سامانه مديريت پسماند دارد. با توجه به اينكه ميزان گازهاي گلخانه اي در سناريوي دوم (تلفيقي از بازيافت، تهيه كود كمپوست و دفن) با توليد حدود ٦٨٠١ تن در مقايسه با سناريوي اول(فقط دفن) با توليد حدود ٩٢١٨ تن مقدار قابل توجهي كاهش را نشان مي دهد، اين‌طور نتيجه‌گيري مي‌شود كه در صورتي كه از روش تلفيقي (سناريوي دوم) استفاده شود، مي تواند منجر به كاهش انتشار گازهاي گلخانه اي به ميزان ٢٦% شود.

Techniques of environmental assessment, including assessment of the environmental impact assessment based on the best seller and implementation of environmental and evaluated based on the environmental impact are some typical methods of evaluation. each has advantages and disadvantages numerous cases of good h~we shown, however, a new approach based on life cycle assessment approach is comprehensive and covers the flaws of the previous assessment. In recent decades, awareness of environmental issues has increased and the public believe that the consumption of goods and use services have large impact on resources and environmental quality and the effects might be in all stages of life cycle the extraction of raw materials to production, distribution, consumption and waste management happen. Integrated management of solid waste (IWM) is the main strategy in dealing with municipal solid waste. In waste management, landfill and incinerators in addition to other methods, such as composting and recycling are also used. The aim of LCA compares a wide range of adverse social and environmental effects of the product and selects the option that is least harmful effects. Materials and Methods It is based on life cycle assessment of urban waste management plan and made available to users at the end to solve some specific problems and combine different elements. In this study, life cycle assessment (LCA) was used as the way in which all environmental impacts associated with a product which is evaluated entire life cycle. For this purpose, various data required were collected. Then all the material and environmental resources and the technology used and emissions of various substances into the environment were assessment (inventory). Finally, the impacts of these materials in the form of a number of environmental indicators were little. The software which is used to get the result of the research is IWM1 in which Environment Council and the plastics industry in Canada by the University of Waterloo to help decision-makers, this model offered. In other words, our model selection and application techniques, technologies and appropriate management programs to achieve specific management goals help waste. Preliminary studies have also shown that model of life cycle assessment method IWM-1 of Iran has not been completed. Therefore, in this study to demonstrate the capabilities and shortcomings of the information model listed, is used for the city Mahdasht. Discussion and Conclusion Compare the scenarios: Two scenarios (case management) for the city Mahdasht were defined: In the first scenario it is assumed that all production waste to landfill 7 by 8395 tonnes a year has passed. In this case, energy consumption 8 is equivalent GJ608. In this case the amount of greenhouse 9 gas emissions by 42 tons of C02, 411 tons and 8765 tons of CH4 + NOX gases is equivalent to 10 C02. The amount of acid gas emissions by 11%, including 0.28 tons of NOX, 0.07 tons and 0.04 tons of HCI is SOX. The May release smoke 12 respectively 0.3 tons of NOX, 2.3 tons and 1.4 tons 13VOCs is PM. The release of heavy metals in the air and release it in the water almost equal to zero, respectively, including 0.42 kg of lead (Pb), 0.006 kg of mercury (Hg), 0.57 kg of cadmium (Cd), 7.556 kg 14BOD and 0.0001 grams of dioxin is 15. In the second scenario it is assumed that the total amount of waste produced 20% of its value (about 1679 tons) into compost 16 and 4% (equivalent to 336 tons) entered the recycling 17. In this case, the amount of waste sent to land fill to the amount of 6380 tons reduced. In this case, the amount of energy used for landfill GJ 331, composting and recycling GJ 371 was 25 GJ. In this case the amount of greenhouse gas emissions in the order of 560 tons of C02, 306 to.ns of CH4 + NOX and C02 equivalent gases is 5910 tons. The amount of acid gas emissions in the order of 0.13 tons of NOX, 0.03 tons of SOX and HCI is 0.028 tons. May smoke emissions by 0.13 tons of NOX, 2 tons is PM and 1 ton of VOCs. emissions of heavy metals 18 in the air and release it in the water almost zero respectively 0.35 kg of lead (Pb), 0.005 kg of mercury (Hg), 0.49 kg of cadmium (Cd), 6.496 kg BOD and 0.00006 grams of dioxins is. Comparing the two scenarios we can see that operations such as composting and recycling significantly reduce the space needed for landfills, reducing energy consumption, reduce emissions, reduce emissions of acid gases, reduce emissions of May smoke, reduce emissions of heavy metals. So that the second scenario from 8395 tons to 6380 tons per year Conclusion The amount of waste sent to landfill which saves considerable space due to the limitation of land to be buried. The amount of waste emissions such as leakage of leachate into groundwater and toxic gases such as methane significantly reduced. Energy consumption of 608 GJ fell to 331 GJ, which is a great savings (due to increased energy prices and limit it). Reduction of greenhouse gas emissions into the atmosphere from 42 tons to -560 tons in the case of C02, CH4 + NOX from 411 tons to 306 tons of C02 equivalent emissions from 8765 tons to 5910 tons; Reduce acid gas emissions into the atmosphere from 0.28 tons to 0.13 tons in the case of NOX, SOX from 0.07 tonnes to 0.03 tonnes HCI from 0.04 tonnes to 0.028 tonnes; May smoke in the NOX 0.3 tons to 0.13 tons, PM and VOCs from 2.3 tons to 2 tons from 1.4 tons to 1 ton, reduce emissions of heavy metals dissolved in water in the case of lead (Pb) of 0. 42 kg to 0.35 kg, mercury (Hg) from 0.006 kg to 0.005 kg, cadmium (Cd) of 0.57 kg to 0.49 kg, BOD of 7.556 kg g to 6.496 kg and dioxins from 0.0001 g to 0.00006 g. (The above results are the result of the calculation IWM software.) The results of this study showed that life cycle assessment is a comprehensive view of the solid waste management system from the point of view of the environment and to be useful tools for decision makers. The results of the current status of waste management system in the case Mahdasht and therefore, may differ from the results of similar studies in other locations due to the different characteristics of the waste, technology and different spatial and temporal factors.