Metals Removal, Recovery, Leaching, and Disposal—Many Ways, One Goal!

Abstract

Mankind’s association with metals can be traced back to 6000 B.C. The Mesopotamians, Egyptians, Greeks, and Romans would never have thought that metals in trace amounts could pollute our ecosystems, namely, water, air, and soil. Moreover, growing industrialization and urbanization have put pressure on government agencies and lawmakers to make stricter environmental policies. The introduction of new stringent environmental regulations means that industries are now being forced to comply with the strict discharge consent levels for both solid wastes and industrial effluent streams. One of the main causes of industrial pollution is the discharge of effluents containing heavy metals, which have adverse environmental and health impacts. Besides having health and environmental effects, heavy metals are nonrenewable resources, and therefore effective recovery of heavy metals is as important as their removal from waste streams. The management of metals in wastes is a significant current topic and debatable issue. The actual and apparent risks associated with metals and their persistence in the environment and disposal pervade every aspect of the metals debate. The varied understandings of risk influence political, regulatory, economic, and social decisions, which in turn influence technical decisions. Metal waste issues are even more complex when coordination is required among programs of various countries to achieve individual management and disposal goals and to set universal regulatory norms. The resolution of this debate is complex, with technical and nontechnical issues of arguably equal merit. This special issue on metal removal and recovery seeks to provide a forum for discussion of the issues associated with metals removal from soils and residues, wastewater and wastewater sludge, leaching, recovery, disposal, and value-addition decisions. Releases of metals and metal compounds to the environment have long been a concern for many regulatory and nonregulatory programs of the U.S. Environmental Protection Agency USEPA due to risks they can pose to human and ecological health. The USEPA conducts a wide range of actions to assess and manage these risks. In June 2002, the USEPA Metals Assessment Work-