According to the Environment Protection Act, 1990, waste is defined as: “any substance which constitutes a scrap material, or an effluent or other unwanted surplus substance arising from application of any process”.
Classification of waste
- Biodegradable waste: These can be degraded through microbial activity. E.g: food residue, human excreta, etc.
- Non-Biodegradable waste: Petroleum, plastic, glasses, etc.
- Bio medical: Needle, syringe, body parts, etc.
- E-waste: Computer parts, batteries, CFL bulbs, etc.
Sources of Waste
- Domestic waste: polythene, bottles, food, cotton, etc.
- Industrial waste
a) Food processing: Organic wastes, pathogens, etc.
b) Paper: Chlorine, sulphur dioxide, methyl mercaptan, etc.
c) Textile: From boiling and processing of fibre
d) Petroleum: Inorganic sulphur, hydrocarbons, organic acids, etc.
e) Chemical: Phosphorus, fluorine, silica, etc.
f) Metal: Copper, lead, chromium, cadmium.
g) Cement: Particulate matter, dust.
h) Nuclear reactor: Radioactive waste.
i) Agricultural waste: Fertilizer, crop residue, pesticide (like DDT), fumigants.
Radioactive waste: X-Ray machines, nuclear plants, laboratories etc.
Municipal waste: Waste produced by public offices, parks, shops etc.
Waste generation in India
With rapid urbanization, industrialization and an explosion in population in India, solid waste management will be a key challenge for state governments and local municipal bodies in the 21st century.
Presently in India, about 960 million tonnes of solid waste is being generated annually as by-products during industrial, mining, municipal, agricultural and other processes. Of this 350 million tonnes are organic wastes from agricultural sources; 290 million tonnes are inorganic waste of industrial and mining sectors and 4.5 million tonnes are hazardous in nature.
However, it’s not the amount of waste generated that’s as much of an issue as the fact that more than 45 million tonnes, or 3 million trucks worth, of garbage is untreated and disposed of by municipal authorities everyday in an unhygienic manner leading to health issues and environmental degradation.
Only 68% of the garbage generated in the country is collected, of which 28% is treated by the municipal authorities. Thus, the poor collection and treatment of waste leads to dumped garbage on streets clearly showing up the poor and inefficient system available to tackle waste management in urban areas. If this issue is not tackled efficiently and better policies and practices for waste management are not adopted, the total waste generation is projected to be 165 million tonnes by 2031 and 436 million tonnes by 2050.
It is interesting to know that untapped waste has a potential to generate from 32,890 TPD of combustible waste, 439 MW of power which is enough to meet the power demand of a union territory like Pondicherry. This includes refuse-derived fuel (produced by shredding and dehydrating garbage) and 72 MW of electricity from bio-gas, as well as 5.4 million metric tonnes of compost annually that could support farming. Plastics, paper and glass constitute 17% of the recyclable waste and this is important because plastic waste, composed of high-calorific-value material, is a crucial fuel for solid waste-to-energy plants.
The amount of waste that is generated, if collected and treated well, can be effectively used to generate energy.
Impact of Waste Accumulation
According to World Health Organization 22 types of diseases can be prevented or controlled by improving solid waste management in India. Hence, people in India as well as local municipal bodies should change their casual attitude towards waste management. A more collective, structured and institutional approach from all stakeholders will be required to address this menace. It can lead to:
- Surface water contamination: Wastes that end up in water bodies negatively change the chemical composition of the water. It affects all ecosystems existing in the water. It can also cause harm to animals that drink from such polluted water.
- Soil contamination: Hazardous chemicals can get into the soil (contaminants). It can harm plants when they take up the contamination through their roots. If human eat plants and animals that have been in contact with such polluted soils, there can be negative impact on their health.
- Pollution: Bad waste management practices can result in land and air pollution and can cause respiratory problems and other adverse health effects as contaminants are absorbed from the lungs into other parts of the body.
- Leachate: A major problem arising from landfills is the discharge of leachate which is formed by water passing through the tip and thus becoming contaminated with various organic and inorganic pollutants. This subsequent movement of the leachate into the surrounding soil, ground water or surface water could lead to severe pollution problems.
- Health impact
- Effect on terrestrial life: lead and mercury poisoning, respiratory disease, decrease in photosynthesis, etc.
- Effects on aquatic life: coral bleaching, algal bloom and death of marine animals.
Methods for Waste Management
Waste management is a collective activity involving segregation, collection, transportation, re-processing, recycling and disposal of various types of wastes.
Different methods are:
- This method involves burying off the waste in the vacant locations around the cities. The dumping site should be covered with soil to prevent contamination. Suitable trees should be planted to hold the soil (of shallow roots).
- Advantage of Landfills: If designed carefully they can serve as economical and quite sanitized method for waste dumping.
- Disadvantage: Mostly unplanned dumping occur in suburbs and slums which causes serious environmental and health hazards. E.g: release of poisonous gases, secretion of toxic liquid, destruction of vegetation.
- It is controlled high temperature oxidation (burning/thermal treatment) of primarily organic compounds that produce thermal energy, CO2 and water.
- Advantages: Useful to deal with large quantities of organic hazardous waste and produces electricity.
- Disadvantages: The installation is expensive (high cost of equipment and skilled operators) and Generates ash and toxic gases (HCL, CO, SO2).
C. Other Thermal Methods
- Pyrolysis: In this process the solid is converted in to liquid state and liquid is converted in to gas. These products of treatment can then be used for the production of energy.
- Gasification: The material to be treated is directly converted in to SynGas (synthetic gas) which has hydrogen and carbon dioxide as its components.
- Bioremediation is the use of living organisms, primarily microorganisms, to degrade environ-mental contaminants into less toxic forms. e.g.: Pseudonymous bacterium can decompose synthetic pesticide.
- Bioremediation techniques are more economical than traditional methods and pollutants can be treated on site, thus reducing exposure risks for personnel.
Waste management can be done in two ways: one is through waste reduction, and two through recycling. Consistent waste reduction and recycling activities mean there will be less waste materials to be sent to landfills and incinerators. As such, the emission of greenhouse gas and other forms of pollutant will be reduced by a large percentage. Reusing and recycling of used items will also result in less production of new products.