Hari Srinivas

Traditionally, urban solid wastes are managed in a hierarchy that looks like an inverted pyramid shown below. At the broad top is landfill, which is a macro solution applied at the level of the city. Very little of the waste is processed or treated in any way, and indeed have a maximum impact on the environment.

At the narrow bottom of the inverted pyramid is waste minimization at source. This is a micro solution to waste management, applied at the level of an individual and household, or a business/industry - at the place where the waste is actually generated. Here a conscious effort is made to reduce the amount of waste generated - indeed to avoid situations where waste is generated. The impacts and effects on the environment at this level minimal.

Ranged in-between the two extremes are other means of waste management - from incineration (with or without energy recovery) to recycle and reuse. It is interesting to note that each level of this hierarchy has been subject to innovative solutions to reduce their impact on the environment, particularly at the upper levels of the pyramind. Methane recovery, leachate management, energy recovery and generation, recycled and secondary products from wastes - for example fly-ash cement from inconerators etc. are some of the approaches adopted.

A second aspect to note is the technical inputs needed increases at the upper levels of the pyramid, than at the lower level. Also, the degree of partnerships needed varies along the pyramid. At the upper levels, it is almost the exclusive perview of local governments, with little inputs from other stakeholders. The bottom of the pyramid derives maximum inputs from a range of stakeholders - where everyone has a role to play.

The Inverted Waste Pyramid provides a big picture in the solid waste management process, and helps in understanding the different inputs and and advantages/disadvantages of each level.