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Received: 20 September 2012 / Revised: 10 January 2013 / Accepted: 23 February 2013 / Published online: 4 April 2013
© Islamic Azad University (IAU) 2013
Abstract Efficient waste paper recycling has a significant role in the sustainable environment. Recyclable waste paper as a fundamental ingredient of municipal solid wastes (MSWs) is indeed an "urban ore". Waste papers are considered as the solid recovered fuel which is recovered from MSW. Recyclable waste papers are segregated into various grades to produce high-quality products. Moreover, sorted paper streams save energy, chemicals, and water, as well as reduce sludge and rejects. Information technology is widely integrated with the waste management industry into its operations such as recycling, reuse, segregating based on categories and so on. This review article focuses on the life cycle of waste paper and existing waste paper sorting techniques. In the paper industry, many types of sensors are used in different mechanical and optical waste paper sorting systems. Such sensors include lignin, gloss, stiffness, mid-infrared, infrared, and color sensors. In this review, also described the effectiveness of different waste paper sorting systems, and finally, recommended appropriate waste paper sorting techniques based on effectiveness and low-cost implementation.
Keywords Waste paper sorting ^ Paper grade ^ Template matching ^ Lignin sensor ^ Stiffness sensor ^ Color sensor ^ Intelligent computer vision
Introduction
Paper comprises a network of plant fibers laid down as a flat sheet that is made from a suspension of plant tissues in water, known as pulp. Etymologically, ''paper'' is derived from ''papyrus,'' the Ancient Greek word for Cyperus papyrus. The plant fiber of waste paper is reusable for six to seven times (Villanueva and Wenzel 2007). Hence, the demand for recyclable waste paper is rapidly increasing in the global market of pulp production. Although the total production capacity of all Malaysian paper mills reaches 1,300,000 tons/year, consumption remains higher than production capacity (Asia Pro Eco Program 2006). The Malaysian pulp and paper industry is heavily dependent on imported fiber, particularly virgin pulp. Hence, the industry has to find a new source of fiber to strengthen and retain the quality of secondary fibers given the growing use of recycled paper in Malaysia. Notably, 90 % of the paper supply is made of recycled fiber...