Sources of Waste Generation

In general, hazardous waste generation can be broadly grouped into two categories, viz., Process-oriented and Pollution Control-oriented. The process-oriented waste is generated during the processing of raw materials to get the finished products; while pollution control-oriented waste originates from the treatment of gaseous and liquid effluents.

The magnitude and characteristics of industrial hazardous waste is dependent on various factors—for example, size of the unit, production technologies, process efficiency and raw materials processed. In India, there are industries generating large quantities of solid waste with relatively less concentration of hazardous constituents, (e.g., metallurgical industry like iron and steel, fertilizers, thermal power stations, etc.). On the other hand, there are other groups of industries dealing with pesticides, electroplating, metal finishing, chlor-alkali, photographic chemicals, etc. which generate comparatively less quantity of solid waste but with high concentration of toxic and hazardous constituents. The later type of wastes require special handling, storage, treatment and disposal techniques.

Nearly 15 per cent of the total solid waste generated by the industries, comes under the hazardous waste category. Though hazardous wastes account for a small proportion of all wastes, their impact can be disastrous as they not only seriously affect the environment but also endanger the human health through inclusion in the food chain.

Prevalent Methods of Disposal

In the absence of proper regulatory control over handling, treatment and disposal, the hazardous wastes are mostly disposed wherever the space is easily available and accessible to the waste generators. Presently, the following methods of disposal of hazardous industrial wastes are followed in our country:

  • Disposal along with city refuse
  • Disposal on river beds and banks
  • Open-pit burning
  • Disposal in low lying areas, estuaries and seas
  • Burning in self-designed incinerators.


Most of the heavy metal bearing and highly toxic wastes containing as pesticides, solvent distillates, phenolics, cyanide waste, etc. are being disposed off using above mentioned methods. From the standpoint of impact what is significant is the method of disposal and the compatibility and complex interaction of these wastes with the receiving environment, a proper evaluation of which 4s. not available in India. Let us see what are the harmful effects of disposal of wastes in an improper way.