Influence of Recycling on the Thermal Properties of Municipal Solid Waste

Abstract

A multitude of conventional and non-conventional techniques are adopted all over the world to handle the huge quantities of municipal solid waste (MSW) generated. Waste reduction, reuse and recycling are instrumental in curbing the issues related to MSW management and are being implemented in many countries including India. Most cities in India have active waste recycling programs. Not only do the recycling programs help in material recovery, but also aid reduction in greenhouse gas emissions by replacing virgin items with recycled items. In the present study, the variation in the calorific values of the MSW generated in the capital city, Delhi, is investigated with possible recycling options for various components. Biodegradables, paper, plastic, metals, etc., from MSW are assumed to be recycled at different rates. Recycling of different combination of MSW components is also considered to analyse the variation in heat content per kilogram. Resultant changes in the combustibility of the MSW and its impact on the efficiency of thermal waste-to-energy facilities are examined. The Tanner diagram and conventional thumb rules are used to interpret the results. While removal of biodegradables, ferrous metals and inert fraction increased the calorific value of the MSW that was left behind, by 18.4, 0.37 and 39.6%, respectively, recycling of paper and plastic fraction of high inherent calorific value reduced the net heat content of the remaining MSW by 5.2 and 18.7%, respectively. Consequently, the position in the Tanner diagram moved towards the areas of high combustibility in the former case and away from the area of high combustibility in the latter case.