Introduction

As societies throughout the world are increasingly moving to greater levels of urbanisation and industrial development, public concern is mounting over the state of the environment, and much attention is now being given to improving the environment for future generations. To achieve this, there has been, particularly in developed nations, major environmental legislation directed towards liquid, solid and hazardous wastes. In most developing countries the situation is less encouraging, where financing is limited, or not available, for the construction of water and waste-treatment facilities and where there is a shortage of trained personnel to operate the systems. Furthermore, in many developing countries there is a lack of official regulations and control systems, no administration bodies responsible for waste control, and little obligation for existing and emerging industries to dispose of waste properly. Also, it is in such countries that there is the greatest movement towards urbanisation and new industrial development, with concomitant destruction of the environment.

Waste generation is a side-effect of consumption and production activities, and tends to rise with the level of economic advance. Wastes arise from domestic and industrial activity, e.g. sewage, waste waters, agriculture and food wastes from processing, wood wastes, and an ever-increasing range of toxic industrial chemical products and by-products. In the final assessment, wastes represent the end of the technical and economic life of products.