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İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Endüstri Mühendisliği Anabilim Dalı / Endüstri Mühendisliği Bilim Dalı

Ağaç bazlı panel endüstrisinde yonga levha atıklarının tersine lojistiği üzerine bir model önerisi

A proposed model for reverse logistics of waste particleboard

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Özet:

Çevre kirliliği; dünya nüfusu ve tüketimin artması, ekonominin büyümesi gibi faktörlerle orantılı olarak artış göstermektedir. Çevrenin kirlenmesi ile birlikte kısıtlı olan kaynakların değeri ve sürdürülebilirliği daha fazla önem arz etmektedir. Yasalar tarafından getirilen zorunluluklar, teknolojik yenilikler, ekonomik bir takım sebepler, toplumun farkındalığı, bilinçli tüketiciler, pazardaki rekabet; şirketlerin ve araştırmacıların kaynak kullanımının verimliliği, geri dönüşüm konularında çalışma yapmalarına ivme kazandırmıştır. Üretim ve üretim sonrası açılarından bakıldığında üretilen ürünlerin müşteriye ulaştırılmasından sonra sona eren zincirin döngü haline getirilmesi hem potansiyel kirliğin önüne geçilmesini sağlayacak hem de kullanılan kaynakların üzerindeki baskıyı azaltacaktır. Tersine lojistik, kullanım ömrünün sonuna gelmiş ürünlerinin tamamının imha edilmesinin önüne geçerek tekrar sisteme dâhil edilmesini sağlamaktadır, böylece çevre kirliliğinin azalması sağlanarak sürdürülebilir gelişmenin bir parçasını oluşturur. Kapalı döngü tedarik zinciri ise üretilen ürünlerin müşterilerden geri kazanılmasını, kazanılan ürünün tamamının ya da parçalarının değer katılarak tekrar kullanılmasını amaçlayan geliştirilmiş tedarik zinciridir, doğal kaynakların kısıt oluşturduğu üretim koşulları düşünüldüğünde tersine lojistik ve klasik tedarik zinciri yerine kapalı döngü tedarik zinciri tüm sektörlerde değerlendirilmeli ve uygulanabilir olmalıdır. Birçok ülkede elektronik alet ve bataryalar, kimyasal ürünler, ağır metaller, kâğıt, cam, plastik gibi atıkların geri kazanımı için mevzuat ve literatürde yapılmış çalışma bulunmaktadır, ağaç ürünlerinin geri kazanımına dair bir Türkiye'de yönetmelik mevcut değildir. Bununla birlikte ağaç bazlı panel üretiminde fazla literatür çalışması bulunmamaktadır. Yapılan tez çalışmasında tedarik zinciri, tedarik zinciri yönetimi, lojistik, tersine lojistik, kapalı döngü tedarik zinciri, karbon emisyonu incelenerek ağaç bazlı panel endüstrisinde tersine lojistik konusu ele alınmış, gerçek bir uygulama incelenmiş ve yıllık toplanacak atıkların maksimize edilmesini amaçlayan doğrusal tamsayılı bir model kurulmuştur. Bu amaçla atıkların toplanacağı potansiyel şehirler belirlenerek 5 yıllık bir periyot ele alınmıştır. 5 yıllık geri toplanacak atık miktarı, lojistik, geri dönüşüm maliyetleri ile bütçe kısıtı altında; üretim, lojistik emisyonu ve aynı miktarın hammadde olarak tedarik edilmemesinden doğan emisyon tasarrufu ile emisyon kısıtı altında ençoklanmaya çalışılmıştır. Yıllık üretimin %1'i, mevcut kısıtlarla anlamlı bir sonuç vermiştir, yıllık üretimin %2'si %5 ve %10'unun geri dönüştürülebilmesi amacıyla bütçe kısıtı gevşetilerek duyarlılık analizi yapılmıştır. İlaveten bütçe, %2, %5 ve %10 kısıtını da sağlayacak şekilde arttırılarak kazanılan atık miktarının üzerindeki etkisi gözlemlenmiş, elde edilen sonuçlar paylaşılmıştır.

Summary:

Nowadays, environmental topics, sustainability have been gaining attention due to population increase, ascending environmental problems, consumption growth. Therefore, the academicians, researchers, governments, public, industries pay attention for this topic and trying to revise regulations and applications. Supply chain controls the relationships between suppliers, vendors, producer, distributer, customer and at that point closed supply chain means collection of products and components to recycle and involve a backward flow. Finally, reverse logistics is a backward flow from customer to producer in order to recover waste. Reverse logistics decrease the amount of waste to be eliminated in company with recycle, re-use and remanufacturing of wastes. When legislation and regulations are combined with consumer awareness; are promoted and companies are obliged to redesign their supply chain and logistics planning. Wood-based panels are produced by using chips and chemicals with the variable concentration of them. Construction, furniture, decoration is an example of usage areas of wood-based panels. There are types of wood-based panels, which are particleboard, high-density fiberboard and medium density fiberboard. On the other hand, wood-based panels has become even more important in furniture and construction sector since it is an alternative to solid wood and natural resources are restricted. In the field of automotive, electronics, aircraft industry, household appliances, paper, glass, domestic sewage; there are regulations and targets of recycling and collecting of wastes in many countries, but especially in Turkey, there are restrict study and regulations at this topic. In this study, supply chain topics are discussed and a model for reverse logistics of waste particleboard is proposed. At the introduction part, environmental issues, the importance of natural sources, diminishing product life, planned obsolescence topic, returns of goods, general information about reverse logistics and the aim of this study has given. At second part, literature about supply chain and management of logistics has been reviewed. The definitions of supply chain, supply chain management, logistics, reverse logistics, closed loop supply chain, green logistics, waste management, product life cycle is given. Also, the importance of reverse logistics, the difference between reverse and forward logistics, the relationship of reverse logistics green logistics and waste management, third party reverse logistics providers, logistics centers is clarified. The drivers (economic issues, social awareness, legislation), barriers, processes (collection/retrieval, inspection, re-sale, transportation, re-work, repair, refurbishing, remanufacturing, recycling, diminishing), actors, costs of reverse logistics and the reasons of return goods are mentioned. Re-sale, re-use and re-distribution has the advantage of direct recovery, while repair, refurbishment, remanufacturing, recycling and diminishing are recovering options in process. For the help of these processes the amount of waste, that will be landfilled, has been decreasing. At third part, literature works about reverse logistics are examined. The increase of environmental problems, legislation controls and awareness of consumer make reverse logistics activities more important position. In recent years, studies at this topic has an incremental growth. Some of the industries which the studies are focused are mentioned above. And the reasons is for the selection of those industries are expensive spare parts (automotive), high value with low volume (aircraft industry), containing aluminum, copper, gold in parts (electronics), containing iron in parts (household appliances). At literature works there are studies related with forecasting of returns, conceptual, terminological, historical development of reverse logistics. Provided models for network design, optimal flow of returns with minimizing costs are also founded. And the studies found are classified by conceptual works, model implementation, optimization works, technical methods and proposed models. On the other hand, literature is examined about reverse logistics of wood-based panels; also the studies are classified by conceptual works, model implementation, optimization works, technical methods and proposed models as before part. Almost 30% of world is recovered by forests and forest industry is an important sector at most countries, while it supplies source of income to 18% of world population. There are studies related with life cycle, carbon footprint, production planning, forecasting, designing model under uncertainty of returns, associated with the limited number of studies. Carbon footprint and measuring instruments are also mentioned at this part. Wood is natural source that can be re-used, renewable; consequently, if it is used in a sustainable manner the damages to the climate and nature can be minimized. At fourth chapter, a real implementation that use 100% recycled wood is examined. The details about production, processes, types of wood-based panels, their usage life, the ingredients, size of the sector and growth, cascade utilization of wood are mentioned. There are studies of particleboard returns but for the other types of wood-based panels, there is no implementation, therefore this study focuses only reverse logistics particleboard wastes. The projects that promote reverse logistics in Turkey is also referred. The real implementation, evolution and current situation with consortiums of recovering wastes of Italy is examined. The current situation in Turkey is also clarified. There is no regulations of recovering of waste woods; therefore, it is hard to set-up a start-up presently. Annually capacity, amount, acceleration, conditions, processes, wastes of production in Turkey is given. The datum of green gas emission and carbon footprint in turkey is also given to show the situation, effects of trees and logistics activities on carbon emission is clarified. In the implementation part of the study, a model is proposed to collect waste woods. The assumptions of model is mentioned. Since the study is in progress in Turkey, for one manufacturer (a dominant firm), only its predicted wastes (from the production amount and the life of products) is accounted for the calculations. First of all, cities are selected to collect waste according to their percentage in total sales, then a collection center is chosen, that minimizes the distance with selected cities and effortless in case of constitute a new plant. Aim of the model is specified as collecting maximum waste form the selected cities, under the constraints of budget, target (recovering min 1% of total production) and emission. Decision variables, parameters, scalers, constraints and objective function of proposed model is expressed. Budget is defined as logistics cost, production cost, earned cost as not paying raw materials. Emission constraint is also defined as transportation of wastes and from the processes to recover them, also earned emission from not using fresh wood. Carbon market makes transactions (buying and selling) of carbon emission possible for a determined fee. Some of the countries for instance Japan, United States of America, New Zealand has begun to use this market. In addition to main model mentioned above, existing of carbon market is also considered; budget constraint is revised for this situation and recalculated. As a result, the constraint of recovering at least 1% of annual production amount with other constraints and objective function has given a feasible solution. When minimum 2%, 5% and 10% of annually product can be collect is tried to recover, budget has become low, therefore budget constraint is relaxed to evaluate the results. In addition to annual production effect on total collected waste, increase of budget has been analyzed. According to the results, it is seen that when target amount increase the budget rises excessively. In the current situation absence of regulation in Turkey by comparison with other countries, without any legislation and pressure, firms are going to be unwilling to recover their wastes due to high costs. For the future works, the effects of existence regulations and legislation, a definite ratio of whole production to recover can be analyzed.