Characteristics of Municipal Solid Waste in Indian Urban Centres
National Environmental Engineering Research Institute (NEERI) has carried out extensive studieson characterisation of solid waste from 43 cities during 1970-1994. The average characteristics have been presented in Tables 3.4 and 3.5. 
The paper content generally varies between 2.9 to 6.5% and increases with the increase in population. The plastics, rubber and leather contents are lower than the paper content, and do not exceed 1% except in metropolitan cities.
The metal content is also low, viz. less than 1%. The low values are essentially due to the large scale recycling of these constituents. During a study in Bombay (1993-94), samples were collected both at the source as well as disposal sites to ascertain the extent of recycling. The paper is recycled on a priority basis while the plastic and glass are recycled to a lesser extent. The biodegradable fraction is quite high, essentially due to the habit of using fresh vegetables in India. The high biodegradable fraction also warrants frequent collection and removal of solid waste from the collection points. The ash and fine earth content of Indian municipal solid waste is high due to the practice of inclusion of the street sweepings, drain silt, and construction and demolition debris in municipal solid waste. The proportion of ash and fine earth reduces with increase in population due to improvements in the road surfaces. Percentage of inert material increases with the increase in population may be due to fast than construction and demolition waste find its way into the municipal solid waste disposal stream.
High ash and earth content increases the densities of municipal solid waste which are between 350 and 550 kg/m3 in Indian cities.
The chemical characteristics indicate that the organic content of the samples on a dry weight basis ranges between 20 to 40%. The nitrogen, phosphorus and potassium content of the municipal solid waste ranges between 0.5 to 0.7%, 0.5 to 0.8% and 0.5 to 0.8% respectively. The calorific value ranges between 800-1000 kcal/kg. Knowledge of the chemical characteristics is essential in selecting and designing the waste processing and disposal facilities.
Ragpickers are observed to be more active in bigger cities. They prefer to remove paper, plastics, rags and packaging and such other material, which is light and also have a high calorific value. The remaining waste hence tends to have a higher inert content and a lower calorific value.
The demolition activity is observed to increase with population leading to increased inert content and reduced organic content in MSW.
