Waste Generation and Management — Methods of Safe Disposal of Waste

It is necessary to segregate waste at source because:

1. Biomedical waste and industrial waste must not be mixed with municipal solid waste consisting of biodegradable garbage as disposal of different garbage is done differently.
2. Waste must be segregated into vegetable/fruits, leaves and garden waste, glass and paper waste at source. The toxic or non-biodegradable chemicals and e-waste must be treated separately.
3. Waste must not be left in open but kept in closed containers for municipal collection.

Precautions that should be observed while collecting the waste are:

1. Collection of waste must be organised area-wise by covered trucks, vans or rickshaws so as to prevent littering on the roads.
2. Day to day collection is very important to prevent spread of diseases contaminating and polluting the environment.
3. Building material, debris and demolition waste must be separately collected and disposed off appropriately.

The waste bins should be kept covered so that it is not exposed to atmosphere, stray cattle and flies. Thus, it helps to avoid spread of diseases. Littering can also be avoided by using covered waste bins.

The waste contains many infectious germs and toxic materials. Manual handling of waste should be avoided so as to prevent people from exposure to dreadful diseases and infections.

Waste is transferred by vehicles like trucks. Vehicles used for transfer or transportation of waste must be specially designed for waste collection. It should be covered because if the vehicles used for transporting waste are not covered they will spread pollution in environment and litter on the roads.

Landfills are the large area on the outskirts of cities where the waste is deposited on or in the ground and covered with earth.

Following factors must be kept in mind while planning a landfill:

1. Land requirement and its cost — the land selected for landfill must depend on the quality and quantity of solid waste.
2. Accessibility — the site of disposal must be located either centrally or near the source of waste generated.
3. Cover — A sanitary landfill requires atleast 15 cm cover of thick compact soil at the end of each day's work.
4. Climate — the frequency of rainfall, the velocity and direction of prevailing wind and overall temperature-time relationship are factors to be considered.

The problems associated with landfills are:

1. Landfills give out a bad odour and affects people living or working nearby.
2. Landfills can contaminate the surrounding water supplies, aquifers and soil by leachate.
3. Landfills create explosive methane gas during the decomposition of waste by bacteria, which can damage plants by leaking into the surrounding soil.

Leachate is formed when rain water leaks into the landfill. As the water percolates through the landfill, chemical processes turn it acidic. This acidic water then dissolves toxic chemicals from common hazardous waste products such as household cleaners, insect sprays and paints. This resulting toxic leachate leaks through the bottom and sides of the landfill and contaminates water and soil.

Composting is defined as the process of decomposition of organic waste into humus. It is the natural process of recycling organic matter, such as leaves and food scraps, into valuable fertilizers that can enrich soil.

There are two ways of composting:

1. Anaerobic composting — The anaerobic decomposition process occurs without oxygen and produces biogas (methane and carbon dioxide) and compost. This process is less prone to odour and doesn't require aeration. The biogas can be used for energy production and the compost is used as a superior soil conditioner.
2. Aerobic composting — Aerobic decomposition occurs in the presence of oxygen and involves bacteria, fungi, and actinomycetes. It is relatively expensive, produces bad odours, requires aeration, uses additives, and produces greenhouse gases. The micro-organisms in the process grow and break down sugars, starch, and organic acids.

Three advantages of composting are:

1. Conversion of organic waste into valuable fertilizers.
2. Reduction of the quantity of waste to be disposed by householder.
3. Recycling of organic materials and nutrients back into the soil.

Segregation

Landfill

Landfill

Cooking gas & electricity

Large area away from the city

Composting involves decomposition of both organic & inorganic wastes

Bacteria, fungi, actinomycetes

Aerobic composting is relatively expensive & emits bad odours.