الفهرس 
Pulp and Paper industryOnly 14 pages are availabe for public view
 |  | from | 106 |  |  |
| | | from | 106 | | |
Abstract
The globe is now-a-days concerned with the impact of environmentally polluting industries which may affect drastically the health of people. The social aspects are also of a great concern to achieve stability in societies. As a result, developed countries have set firm regulations for industrial activities to minimize environmental and social damage due to polluting activities. Due to these facts, various researches in the industrial fields are directed in an attempt to reach industrial solutions that besides maximizing the profit; it maintains acceptable environmental and social levels.
In this research, a multi echelon multi product single facility reversed paper manufacturing supply chain is modelled and optimized for sustainability. The behaviour and performance of the supply chain is studied for several parameters and different supply chain designs.
The proposed supply chain in the present work is assumed to be of a reversed type where waste paper is collected from the market from different sources. The quantities of needed waste paper are used for paper manufacturing and the excess quantities may be sold to other facilities with profit. Unrecyclable waste materials are spent either by landfilling or incineration. The manufacturing facility produces three different types of paper of different qualities. The paper is manufactured either entirely from virgin pulp or entirely from recycled waste paper pulp or of a mixture of both.
The study of supply chain sustainability considers marginal profit, environmental impact and social aspects as represented by the number of generated job opportunities. The present study considers the optimization of the marginal profit as a single objective after which the obtained results are compared to that obtained from optimizing for sustainability (i.e. marginal profit, environmental impact and social aspect). The research is extended to study the effect of a number of supply chain drivers such as plant capacity, material mix on supply chain performance. Each of these drivers can be developed and managed to emphasize responsiveness or efficiency depending on the business requirements.
Linear programming was used to optimize the supply chain for maximum marginal profit. The linear programming problem was solved using excel solver. Multi-objective optimization for sustainability was made using NIMBUS software which uses interactive optimization.
It was found that the production capacity has an obvious effect on the three objectives subject to optimization. As the production capacity increases the marginal profit increases showing net profit at certain breakeven capacity which depends on the waste paper cost. The higher the waste paper cost the higher the breakeven capacity.
The product mix from the three types of paper (types A, B, and C) at any production capacity depended mainly on the waste paper cost introduced as a ratio of virgin pulp cost. It was found that in profit optimization, the higher the waste paper cost the higher the tendency for the manufacturing of high quality paper type A as the recycling becomes less profitable. On the other hand, in case of a supply chain that is optimized for sustainably, the opposite takes place as the product mix with increased waste paper cost, the supply chain has to keep producing from low quality paper type C. This is because that in this case, part of profit should be sacrificed to maintain good environmental and social aspects which recommend recycling.
The capacity of the facility plays an important role in determining the product mix. In case of single objective, at small limited capacity the facility has to produce from type C as this type gives the higher marginal profit. As capacity increases other types of papers are introduced according to marginal profit to gain profit limited by the maximum demand on each type. At high waste paper cost, because the marginal profit of type A may be higher that of C, the facility will prefer to produce from type A even at small capacities. In multi-objective, although the marginal profit is less, however the improvement in environmental impact and social aspects are high enough to encourage sacrificing part of the profit.