6.1 Introduction

As the world population grows and its natural resources diminish, the concept of waste is changing. Generally waste is considered as those chem­icals and materials that are either used and discarded or those that are perceived to have little direct use potential for human or animal needs. Currently, the preferred mode is to recycle and reuse waste or discard it in landfills. Not all materials are recyclable or can be reused without further treatment or conversion. The new concepts of Enhanced Waste Management (EWM) and Enhanced Landfill Mining (ELFM) put landfill­ing of waste in a sustainable context [1, 2]. In these new concepts, a landfill is no longer considered as a final solution but a temporary storage place before the stored waste is reused through an appropriate conversion pro­cess [3]. Thus, ELFM offers an opportunity to select an appropriate path for the conversion of waste into either materials (waste to product, WtP) or energy (waste to energy, WtE) and thereby reuse all waste to the extent new technologies and environmental regulations allow. The success of these new concepts depends not only on the technological improvements and breakthroughs but also on a multitude of socioeconomic barriers such as regulations, social acceptance, economic uncertainty, and feasibility of a particular technology in the given environment which prevents the emis­sions of CO2 and pollutants [2].

An integrated solid waste management is typically governed by the pro­cess (often known as the "Ladder of Lansink") which specifies a generally accepted hierarchy of preferred methods of dealing with different types of waste. Direct recycling and reuse of waste is preferred, however, this is not always possible. Numerous technologies are now available to convert each type of waste either to energy or to a reusable product. This chapter exam­ines these technologies and associated processes to obtain the desirable out­comes. The chapter also briefly examines the environmental and economic issues associated with various conversion processes.