Solid waste management.

Solid waste management has changed dramatically through time. Until the twentieth century, solid waste was managed primarily for military reasons and the aesthetic pleasure of the wealthy. For example, ancient Athens and medieval Paris created laws to prevent the buildup of trash outside the city walls, because such a buildup could allow enemies to scale those walls. In the twentieth century, large-scale waste management was instituted in many industrialized countries for aesthetic and health reasons, primarily by dumping in landfills. In the last decades of the twentieth century, resource, energy, and environmental considerations led to dramatically increased recycling and energy recovery. These efforts reduced the need to obtain raw natural resources to meet society’s needs. Currently, solid waste management strategies necessarily vary by location, and the optimum strategy in one location is not necessarily the same as that of another. However, in almost all cases, the amount of waste generated continues to increase, and so solid waste management becomes an essential part of resource management.