The functional elements of waste management are: storage, segregation, collection, transportation, treatment and disposal. Presently, most of the metropolitan cities MSWM system includes all the elements of waste management where as majority of small cities and towns MSWM system comprises only four activities collection, storage, transportation and disposal (Sharholy et al., 2008, Ramachandra, 2009; 2011).

• Waste storage: Storage of waste means the temporary containment of waste, at house level or at community levels. At household level, old plastic buckets, plastic bins and metal bins are used for storing waste and at community level, wastes are stored in masonry bins, cylindrical concrete bins, metallic and plastic containers (Joseph, 2002; Kumar et al., 2009). Stored wastes are collected and transported to the transfer station or processing site at regular intervals.

• Waste segregation: Waste segregation is to segregate the waste into different categories like; wet or organic waste and dry or inorganic waste. In the conventional method, partial segregation of news paper, milk pouches, etc are happening at house level, but rest get mixed up during waste storage. In few places with the active participation of NGO and community, segregation at source/ at house level is in place (Pattnaik and Reddy, 2009; Ramachandra, 2009). However, it is still at very preliminary stage. Informal recycling sector play an important role in waste segregation and waste management (Sudhir et al., 1996).

• Waste collection: Waste collection is the removal of waste from houses and all commercial places to collection site from where it will go for further treatment or disposal. Its efficiency is a function of two major factors; manpower and transport capacity (Gupta et al., 1998). Community bin and DtD collection are the collection systems which are prevalent in India (Kumar et al., 2009; Kumar and Goel, 2009; Pattnaik and Reddy, 2009; Ramachandra, 2009). Indian cities are shifting from community bin collection to DtD collection to improvise the existing waste management system. Most of the cities are either fully or partially covered with DtD collection (Kumar et al., 2009). In Kolkata DtD collection facility is only limited to 60 - 61% in present collection system (Chattopadhyay et al., 2009; Hazra and Goel, 2009), where as in Bangalore it has reached up to 94 - 100% of total waste collected from residential area (Ramachandra and Bachamanda, 2007; Kumar et al., 2009).

• Waste transportation: Waste transportation of the stored waste to final processing sites or disposal sites at regular intervals is essential to avoid bin overflow and littering on road. Usually light and covered vehicles with carry capacity of around 5 tons per trip are used for transportation of wastes (Rajabapaiah, 1988, Ramachandra, 2009). In small towns bullock carts, tractor-trailers, tricycles etc. are mainly used for transportation (Sharholy et al., 2008).

• Waste treatment and recovery: The method adopted for treatment of organic waste is either composting or biomethanation. Composting through aerobic treatment produces stable product- compost which is used as manure or as soil conditioner. In metropolitan cities, compost plants are underutilized due to various reasons, most important reasons are unsegregated waste and production of poor quality of compost resulting in reduced demand from end users (Kumar et al., 2009, Chattopadhyay et al., 2009, Ramachandra, 2011). Vermi-composting is also practiced at few places. Biomethanation through microbial action under anaerobic conditions produces methane rich biogas. It is feasible when waste contains high moisture and high organic content (Chanakya et al., 2007; Kumar and Goel, 2009). Recyclable waste which can be transformed into new product like plastic, rubber, glass, metal and others are collected separately and auctioned by recycling industries (Agarwal et al., 2005).

• Waste disposal: Waste disposal is the final stage of waste management. As in urban area, uncontrolled and unscientific disposal of all the categories of waste including organic waste has lead to the environmental problems such as contamination of land, water and air. In larger towns or cities the availability of land for waste disposal is very limited (Gupta et al., 1998; Mor et al., 2006; Ramachandra, 2009). In many places, a major fraction of urban wastes are directly disposed in low lying area or in hilly area at city outskirts (Lakshmikantha, 2006; Talyan et al., 2008; Chattopadhyay, 2009). In this backdrop, MSW rule 2000, GOI (Government of India) was introduced to regulate all components of waste management. Landfilling or disposal is restricted to non-biodegradable, inert waste and other wastes that are not suitable either for recycling or for biological processing as per MSW rule, 2000.