The nine different processes or units are separate and well defined. However, the inputs and outputs of the nine units are closely linked to each other. When all the units are considered together, the only input to the whole system is “undesirable” waste and the outputs are useful products.
Individual processes or units are in circles. A circle is colour coded according to the desirability of the waste or product associated with the process. The dark red color represents most undesirable, while the dark green represents most desirable. The amber and lighter shades of red and green represent intermediate products. The process in the white circle, which represents federation activities like accounting, provides support to the rest of the processes and is in turn dependent on them.
An individual unit has its own sub-processes and operates on its own fixed time schedule. For example, the waste collection is done every day, while aerobic composting takes 35 days to create compost from organic matter. The sub-processes in a particular unit may be interlinked within the unit, e.g. in vermicomposting, the earthworms which are produced in the process are partly reintroduced in a fresh vermicompost bin to continue the process. The individual processes are designed to be user and environment friendly, and mostly use local technologies that are not energy intensive.
From the figure we can see the interlinking of the different units. The output of one unit is an input of one or more other units which is shown by arrows. For example, vegetable waste from the secondary segregation unit goes to the cattle shed while cow dung from the cattle shed goes to the composting, vermicomposting and drying units. We can see the systematic handling of waste from one process to another, increasing its desirability at each stage of processing.
The “Vellore model” of ZWM with separate units which work together for a common objective can be described in a nutshell as a “centralized project with decentralized processes”.