en تخصصي Special پژوهشي Research <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span sans-serif="" style="font-family:Calibri,"><span new="" roman="" style="font-family:" times="">Solid waste has become one of the most critical environmental issues in the world. Therefore, a waste management system to prevent further destruction of the environment is essential. Waste management includes collection, transport, cleaning, recycling, and disposal of the wastes. In recent years, due to environmental concerns, manufacturers have been forced to offer environmentally friendly products. So, the area of reverse logistics (RL) has recently received considerable attention, due to a combination of environmental, economic, and social factors.</span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span sans-serif="" style="font-family:Calibri,"><span new="" roman="" style="font-family:" times="">In this research, the design of a multi-product and eleven-level reverse logistics network is conducted, which collects all the waste in one place and separates them according to the needs of the factories (in terms of the type and material of the waste, etc.) and sends them to the intended destination. This model can support all kinds of industries in which the revival of recycling and destruction of products. </span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span sans-serif="" style="font-family:Calibri,"><span new="" roman="" style="font-family:" times="">This study provides a mixed integer mathematical model to reduce the costs of the whole system</span><span dir="RTL" lang="AR-SA" new="" roman="" style="font-family:" times="">.</span><span new="" roman="" style="font-family:" times=""> The number of centers, the number of products and parts that should be sent from one center to another, the amount of CO₂ emissions, and the total cost of the model were determined. Finally, the sensitivity analysis was done on the parameters of the model</span><span dir="RTL" lang="AR-SA" new="" roman="" style="font-family:" times="">.</span><span new="" roman="" style="font-family:" times=""> The model was validated by changing the input data in two different cases.</span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span sans-serif="" style="font-family:Calibri,"><span new="" roman="" style="font-family:" times="">Sensitivity analyses are conducted on various parameters to illustrate the capabilities of the proposed model. The results reveal that the allowed cost of CO₂ emissions has a significant effect on the value of the objective function.</span></span></span></span></span><br> <span style="font-size:11pt"><span style="line-height:normal"><span style="unicode-bidi:embed"><span sans-serif="" style="font-family:Calibri,"><span style="font-family:"Times New Roman","serif""></span></span></span></span></span> Model, Optimization, Reverse Logistic, Waste Management, Environmental Impact. 69 90 http://ijorlu.lahijan.iau.ir/browse.php?a_code=A-10-536-1&slc_lang=en&sid=1 M. kakooee mahtakakooee99@gmail.com 10031947532846001707 10031947532846001707 No Department of Industrial Management, South Tehran Branch, Islamic Azad University, Tehran, Iran M. Modiri m_modiri@azad.ac.ir 10031947532846001708 10031947532846001708 Yes Department of Industrial Management, South Tehran Branch, Islamic Azad University, Tehran, Iran Gh. Abbaspour Esfeden gh_abbaspour@azad.ac.ir 10031947532846001709 10031947532846001709 No Department of Industrial Management, South Tehran Branch, Islamic Azad University, Tehran, Iran