Disposal of solid waste is done most commonly through a sanitary landfill or through incineration.
Landfill: A modern sanitary landfill is a depression in an impermeable soil layer that is lined with an impermeable membrane. The three key characteristics of a municipal sanitary landfill that distinguish it from an open dump are:
Solid waste is placed in a suitably selected and prepared landfill site in a carefully
Prescribed manner.
The waste material is spread out and compacted with appropriate heavy machinery.
The waste is covered each day with a layer of compacted soil.
Production of methane in the landfill might lead to explosion when it gets mixed with oxygen, hence it requires a venting system
Difficult to find suitable land filling sites.
Incineration: Process of burning municipal solid waste in a properly designed furnace under suitable temperature (815 C) and operating conditions. It reduces the solid waste by 90% in volume and 75% in weight.
Problems:
Air quality problems, toxicity and disposal of fly and bottom ash.
Extensive air pollution control equipment, high level technical supervision and skilled employees for proper operation and maintenance are required.
Vermicomposting: All dead and dry leaves and twigs decompose and are broken down by organisms such as earthworms to form a dark rich soil-like material called vermicompost. These earthworms in the soil use the organic material as food, which in turn provides them with nutrients for their growth and activities. These nutrients are returned to the soil to be used again by trees and other plants. This process recycles nutrients in nature. This soil can be used as manure for farms and gardens.
Steps for vermicomposting:
Dig a pit about 3’ wide and deep and length can be of any size depending on the availability of space.
Line it with bricks joined with minimum cement to avoid the entry of rodents into the pit.
Bottom of the pit can be covered with coconut fibre to retain the moisture content.
Arrange the dried leaves and twigs; and dry dung in alternate layers with a thickness of 1” layer. Then introduce earthworms about 4000 in no. for one square meter.
Cover the worms with alternate layers of partially decomposed dried leaves and twigs; and dung.
Cover the top of the pit with a gunny bag to maintain a low temperature.
Water the pit once or twice a day to keep it moist.
In about 45 days the waste will be decomposed by the action of worms.
The soil derived is fertile and rich in nutrients.
Composting: Composting refers to treatment of waste through aerobic decompositions of biodegradable organic matter. Under natural conditions dead vegetable and animal materials decompose under the influence of bacteria and fungi, wherever they fall and add to the fertility of the soil. This process can be either aerobic or anaerobic. Composting has three products; compost as an organic fertilizer, salvaged materials for resale and non-compostable as land fill materials. Compost is brownish, peaty material, the main constituent is humus.
Of all the methods discussed above, source reduction and recycling are the effective methods for solid waste disposal, which includes 4 ‘Rs’ for waste management, i.e. Refuse, Reuse, Recycle & Reduce. Refuse. Instead of buying new containers from the market, use the ones that are in the house. Refuse to buy new items though you may think they are prettier than the ones you already have. Reuse. Do not throw away the soft drink cans or the bottles; cover them with homemade paper or paint on them and use them as pencil stands or small vases. Recycle. Use shopping bags made of cloth or jute, which can be used over and over again {will this come under recycle or reduce?}. Segregate your waste to make sure that it is collected and taken for recycling. Reduce. Reduce the generation of unnecessary waste, e.g. carry your own shopping bag when you go to the market and put all your purchases directly into it.
