بهینه‌سازی شبکۀ همزیستی‌ صنعتی با در نظر گرفتن مشخصه‌های توسعۀ ‌پایدار

شهرک‌های صنعتی با وجود دستاوردهای خود، تاثیرات مخربی بر محیط‌ زیست داشته‌اند و گاهی به موضوعات مرتبط با رفاه اجتماعی توجه نکرده‌اند؛ بنابراین، طراحی آنها باید متناسب با اهداف توسعۀ ‌پایدار و اصول اکولوژیک بهبود یابد. یکی از اقدامات موثر در این زمینه، پیاده‌سازی شبکه‌های همزیستی‌ صنعتی است. شبکه‌های همزیستی، مجموعه‌ای از صنایع است که با هدف اشتراک‌گذاری ضایعات هر صنعت به‌عنوان مادۀ ‌اولیۀ صنعت دیگر در کنار هم قرار گرفته است و امکان تبادل انرژی و مواد را فراهم می‌آورد. در این پژوهش، یک مدل برنامه‌ریزی عدد صحیح مختلط دوهدفه برای بهینه‌سازی شبکه‌های همزیستی ارائه شده‌ است که به‌طور هم‌زمان، انتقال ضایعات و مواد اولیۀ جامد، مایع و گاز را فراهم می‌کند. هدف اول، حداقل‌سازی هزینه‌های اقتصادی اجرای شبکه و صنایع مشترک در آن و هدف دوم، حداکثرسازی رفاه ‌اجتماعی را فراهم می‌آورد. بعد محیط‌ زیستی با محدودیت‌های مدل کنترل می‌شود. برای اعتبارسنجی مدل پیشنهادی، به پیاده‌سازی آن بر یکی از شهرک‌های صنعتی استان البرز اقدام شده است. برای حل مدل از روش اپسیلون محدودیت استفاده شده ‌است که نتایج خروجی نشان می‌دهد، حجم ضایعات بدون ‌استفاده و هزینه‌های صنایع در شرایط همزیستی نسبت ‌به پیش از آن کاهش یافته ‌است. همچنین، ایجاد 23 فرصت شغلی ازجمله مزایای بهبود سطح اجتماعی است.

Industrial symbiosis network optimization considering sustainable development characteristics

Purpose: Despite their achievements, the industrial parks have had a devastating effect on the environment and sometimes did not address social welfare issues. Therefore, it is necessary to improve their design based on the characteristics of sustainable development and ecological principles. One of the effective measures in this regard is Industrial Symbiosis (IS). It is a set of integrated plants aiming to exchange the waste of each plant as the raw material of another plant. Although several models have been presented for the optimization of water or energy exchange, one of the purposes of this research is to simultaneously exchange raw materials and waste in solid, liquid, and gas types. Considering the social characteristic of sustainable development is another necessity of this research that has been less discussed. Also, a significant portion of the waste needs to be recycled and cannot be exchanged directly between plants. Therefore, another purpose of this research is to increase the productivity of the model considering material flow between plants and recovery centres, which did not exist in previous models. Design/methodology/approach: In this research, a twoobjective mixedinteger linear programming model is proposed considering the characteristics of sustainable development, which simultaneously enables the exchange of all raw materials and waste. Providing recyclable waste exchanges via recovery centres is another strength of the proposed model. The first objective is to minimize the economic costs of the IS network, and the second objective is to maximize social welfare. The environmental characteristic is also controlled by model constraints. Finally, to validate the proposed model, it has been implemented in one of the industrial parks of Alborz province. Also, to solve the model, the εConstraint method has been used. Findings:  According to the model’s results, most of the plant’s waste was replaced by the input raw materials of other plants, while before IS, all plant waste was disposed and all input materials were supplied through fresh materials. Therefore, the findings of the proposed model are as follows:reducing the volume of disposed and useless plant waste and its costs;reducing the volume of fresh input raw materials plants and its costs;creating 23 job opportunities through the establishment of centres to recover;compensating for lost working days due to the reduction of environmental pollutants to achieve the social characteristics of sustainable development; andimproving the characteristics of sustainable development in the industrial park compared to the time before IS. Research limitations/implications: This research, like other studies, has assumptions and limitations in model development. For example, the transmission path of all three types of material and waste was considered the same. The feasibility of situations tradeoff and the use of waste of recovery centres was not studied. Also, the expectations of the park and the plants were considered in an integrated manner. Therefore, the following subjects are suggested to improve and develop the model in future studies:design of IS network using bilevel models;development of a model for the use of waste from the recovery centre; for example, methane gas or sludge treatment plant;model development by considering seasonal plants through reliability inventory models and intermittent flows;development of a model for locating and allocating unusable waste in the current network to the new plant; anddevelopment of a model based on the different transmission paths for material and waste flow in solid, liquid, and gaseous according to the research assumption 3. Practical implications: One of the most significant applications of this paper is the simultaneous optimization of exchange material and waste in three types of solid, liquid, and gaseous in IS network to achieve the characteristics of sustainable development. Also, reducing the cost of input material and waste disposal compared to the time before IS are the economic advantages of this research.Social implications One of the aims of this paper was to reduce the environmental and social impact of the industrial park to achieve the characteristics of sustainable development. For example, reducing the volume of fresh input raw materials and disposed waste plants and job creation were the environmental and social advantages of this study. Originality/value: The innovations of this research include the following:simultaneous optimization of material and waste flow in three types: solid, liquid, and gaseous;considering the social characteristic of sustainable development; andconsidering the exchange between recovery centres and plants to use the waste in need of recovery.