SOLID WASTE AND ITS CONCEPTS 

WHAT IS SOLID WASTE SOLID WASTE?

Solid waste is defined as any waste that is dry in form and is discarded by people as unwanted.

Human activities create waste and these wastes are handled, stored, collected and disposed of, which can pose risks to the environment and to public health (Saxena et al., 2010; Zhu et al., 2008). The term 'waste' defies precise definition; the Oxford Dictionary ¹ says that, this word can be used as an adjective, a noun and a verb. For our present purpose, we are concerned with its use as a noun, but, even then its meaning varies widely. While dissecting the past of the word, Kharbanda and Stallworth have mentioned that, the word 'waste' is partly of French origin and they have given the different meanings of the word such as from desert, to municipal waste to waste water.

Solid waste has been defined as "useless, unwanted or, discarded materials that arise from human activities and are not free flowing" (WHO Expert Committee, 1971). The definition of solid waste varies from country to country' and based on the management approach. Solid waste is also internationally defined as non-liquid waste. "Non-liquid1 is a relative term because sludge’s (which is semiliquid) of certain kinds are within the scope of solid waste; i.e., industrial sludge from industrial sources, sewage treatment plants sludge etc. (Flint off, 1984).

Solid waste is garbage, refuse, and other discarded materials, generated from industrial, commercial, domestic and agricultural activities (Prasad, 2000). Solid waste is a general term used for heterogeneous by-products of manufacturing and discarded goods which have negligible economic value to the owner (Bhattacharya, 1997, Kumar et al., 1999).

Municipal Solid Waste

The term municipal solid waste (MSW) is normally assumed to include all of the wastes generated in a community, with the exception of waste generated by municipal services, treatment plants, and industrial and agricultural processes.

Municipal solid waste (MSW) is the solid waste generated from urban activities. The term refers to all solid wastes collected and managed by the Urban Local Bodies (ULBs) and comprises of diverse categories of waste (Dutta and Mahendra, 1997 and Bhattacharyya, 1997). Municipal solid waste is defined as the solid waste generated within the territorial limits of a municipality independent of its characteristics and sources (Buenrostro et al., 2001).

Source of Municipal Solid Wastes

The classification of municipal solid wastes is considered on the basis of sources i.e. Residential and non-residential. The composition of solid waste generated from residential area widely differ from non-residential area (Commercial, institutional, industrial etc.). Further classification of the residential area can be made on the basis of activities i.e. residential, commercial, market etc. The waste composition significantly depends on the type of activities. The major sources of solid waste are described below:

1-Household waste

The food habit and cooking methods have a major influence on composition and quality of municipal solid waste in a locality. Household waste is the largest source of municipal solid waste. It contains materials such as leather, paper, rubber, glass, batteries, discarded containers etc. The composition of household waste has a direct link with the socio-economic condition of the residential area. The per capita waste generated in an affluent colony is generally higher than an economically backward colony. Vegetable markets are often the major sources of solid waste, which mostly comprise of biodegradable organics. Other sources include stores, offices, restaurants, warehouses, hotels, etc. The fish markets also generate considerable quantity of biodegradable solid waste.

2-Institutional refuse

Institutional wastes are those arising from institutions such as schools, colleges, universities and research institutes large hotels, restaurants community halls and religious places. Institutional waste mostly comprises of waste paper, leftover food items etc. The institutional waste mostly contains recyclable wastes.

3-Street sweeping

Street sweeping is a regular activity of the municipalities. The refuse includes dirt and litter. It may also contain household refuse, drain cleanings, sludge etc.

4-Construction debris

Construction in urban areas is an ongoing activity. The construction debris often are dumped on the streets. This mostly contains inorganic substances. These are either lifted privately or by the Municipal Corporation or dumped in landfills.

5-Ashes and residues

Wood, cow dung, coal and coke are the major fuel used by the roadside hotels and economically backward people. Ashes and residues arising from burning of solid fuel are normally composed of fine, powdery materials, cinders, clinkers, and small amounts of burnt and partially burnt materials.

6-Animal wastes

Khatals are essential evil in urban areas. Dung, reject feed, etc are the major waste from khatals. This causes unpleasant odour and insanitary condition in the surrounding, if not managed properly.

7-Rubbish

This includes combustible and non-combustible solid waste, excluding food waste or other putrescible materials. Combustible rubbish consists of materials such as paper, cardboard, plastics, textiles, rubber, leather, wood, furniture, and garden trimmings. Non-combustible rubbish consists of items such as glass, crockery, tin cans, ferrous and non-ferrous metals, dirt, etc.

8-Dead animals

Dead stray animals like pigs, dogs and domestic animals pose major problems to the urban environment. Carcasses of dead animals are required to be removed and disposed off separately. A large quantity of wastes is generated from municipal abattoirs and from roadside butchers, which consist of body parts of animals. Illegal butchering of animals, carried out in an extensive scale in public areas result in dumping of remnants in the surroundings (Sandra Cointreau, 1987, Moitra, 1996, Bhattacharya, 1997, Tripathy et a!., 1997, Patkie et al, 2000).

Urban Solid Waste Classification and Characteristics:

Table 1.1: The urban waste classification and characteristics are summarised in.

S.NO	WASTE	SOURCE	CHARACTERISTICS
1. 2. 3. 4. 5. 6. 7. 8. 9. 10.	REFUSE Burning Ash Construction wastes Industrial wastes Sewer Sludge Road Clinical waste Agricultural wastes Animal wastes Offal	(a)    Domestic or Household      (b)Institutional     (C) Market or             Commercial Solid Fuel Burning Construction/ Demolition/Modification Industries Sewer cleaning Road sweeping Nursing homes/ Hospitals Crop Yield Khatal Butchering, Abattoir	Biodegradables (vegetables, food waste, oil, cloth wood etc.) Non-biodegradables (Packing, Polythene bags, battary etc.) Combustible (Textile, Rubber) Combustible (papers, Polythenes, Metals) Non-Combustible (metals, Glass etc.) Biodegradables and combustible. Generally inert Generally inert Hazardous and Non-Hazardous Biodegradable and inorganic Polythenes, waste paper, Leaves, Dust etc. Hazardous and Toxic Organic, Combustible Biodegradable Biodegradable Biodegradable

Source: Flintoff,F., Management of solid waste in developing countries, WHO, 1984.

Functional elements of waste generation:

S.No	Functional elements	Description
1. 2. 3. 4. 5. 6.	Waste generation Waste handling and separation, storage and processing at the source Collection Transfer and transport Separation, processing Transformation of solid waste Disposal	Waste generation encompasses those activities in which materials are identified as no longer being of value and are either thrown away or gathered together for disposal. What is important in waste generation is to note that there is an identification step and that this step varies with each individual. Waste generation is, at present, an activity that is not very controllable. Waste handling and separation involve the activities associated with managing wastes until they are placed in storage containers for collection. Handling also encompasses the movement of loaded containers to the point of collection. Separation of waste components is an important step in the handling and storage of solid waste at the source. On-site storage is of primary importance because of public health concerns and aesthetic considerations. Collection includes both the gathering of solid wastes and recyclable materials and the transport of these materials, after collection, to the location where the collection vehicle is emptied, such as a materials-processing facility, a transfer station, or a landfill. The functional element of transfer and transport involves two steps: (1) the transfer of wastes from the smaller collection vehicle to the larger transport equipment, and (2) the subsequent transport of the wastes, usually over long distances, to a processing or disposal site. The transfer usually takes place at a transfer station. Although motor vehicle transport is most common, rail cars and barges are also used to transport wastes. The means and facilities that are now used for the recovery of waste materials that have been separated at the source include curb side collection and drop-off and buyback centres. The separation and processing of wastes that have been separated at the source and the separation of commingled wastes usually occurs at materials recovery facilities, transfer stations, combustion facilities, and disposal sites. Transformation processes are used to reduce the volume and weight of waste requiring disposal and to recover conversion products and energy. The organic fraction of MSW can be transformed by a variety of chemical and biological processes. The most commonly used chemical transformation process is combustion, used in conjunction with the recovery of energy. The most commonly used biological transformation process is aerobic composting. Today, disposal by landfilling or land spreading is the ultimate fate of all solid wastes, whether they are residential wastes collected and transported directly to a landfill site, residual materials from MRFs, residue from the combustion of solid waste, compost, or other substances from various solid waste processing facilities. A modern sanitary landfill is not a dump. It is a method of disposing of solid wastes on land or within the earth’s mantle without creating public health hazards or nuisances

Main concept of Solid waste management

 SWM can be classified into five main stages. These stages are also referred to as the functional elements of Solid waste management. These are:

(a)    Onsite handling, storage and processing

(b)    Collection of solid waste

(c)    Transfer and transport

(d)    Resource recovery and processing

(e)    Disposal of solid waste.

Onsite handling, storage and processing methods are undertaken at residential or household level. It includes compacting waste by squashing it and changing its size and shape for easy handling. This also includes sorting the waste in order to separate the items that can be reused or recycled. For example, organic waste should be separated out for composting as part of onsite handling. Bottles and cans made of metal can be reused. Collection and transfer or transport activities are not common in rural areas because the waste is usually disposed of immediately onsite in a prepared waste disposal or composting pit. Ideally, waste management should go beyond pollution prevention and disease prevention for humans and should benefit society by providing economic gains for families and communities. The preferred approach for dealing with solid waste is Integrated solid waste management (ISWM).

REFERENCES:

Kumar, K. and Nand, N. (1989,364). It is located in the Garhwal region of Uttarkhand, Dehradun came into existence during the medieval period. These old towns were either administrative headquarters or pilgrimage centres when British made Dehradun the headquarters of Gurkha army, it set the stage for the sprouting of modern urbanization in Garhwal. (Kumar, K. and Nand, N.,1989, 356).Journal of Development Issues 1(2):9-106.

Bhattarai.R.C. (2000) analysed the household behaviour on solid waste management in Kathmandu metropolitan city and found household size and income as the major determining factors for the total quantity of wastes generated.