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| MUNICIPAL
SOLID WASTES |
WEALTH FROM WASTES: TECHNOLOGIES :
In the recent past, private sectors have taken initiatives to use the garbage
as profitable venture. Some of the technological options available are summarized
below:
Energy Recovery Technologies
Biomethanation
Anaerobic digestion
is process used for biological decomposition of organic wastes. The organic wastes
are hydrolyzed, liquified and gasified with the help of methanogenic bacteria.
There is an appreciable saving in recurring costs in such prcesses because of
the utilization of bio-gas.
Sanitary
Land-fill Gas
Sanitary land filling is a process of dumping of solid waste in a scientifically
designed land area spreading waste in thin layers, compacting to the smallest
practicable volume and covering with soil on daily basis. The methane rich biogas
is produced due to anaerobic decomposition of organic matters in solid wastes.
Garbage has a potential to generate about 150-250 cubic metre biogas per tonne
waste depending upon the quality.
Pelletisation
Fuel pellets
also referred as refuse derived fuel (RDF) are small cubes/cylindrical pieces
made out of garbage. Its calorific value, 4000 Kcal/kg of the product is quite
close to the coal, therefore, it can be good substitute for coal, wood etc.
Pyrolysis/Gasification
In this process, combustible matter of
garbage is allowed to dry/dewater and then is subjected to shredding. Incineration
of waste under oxygen-deficient conditions is called pyrolysis. The objective
of pyrolysis has generally been to produce gas, which would be stored and used
when required.
Incineration
Incineration is a process of
controlled combustion for burning of wastes and residue, containing combustible
material. Carbon dioxide, water vapour, ash and non-combustibles are end products.
The heat generated during incineration is recovered and utilized for the production
of steam, heating water and generating electricity. Incineration is used to achieve
maximum volume reduction of solid waste and when there is shortage of land filling
facilities. It is usually cost effective method of disposal.
Composting
Composting is one of the methods of waste utilization. It is defined as the
decomposition of heterogeneous organic matter by a mixed microbial population
in the moist, warm and aerobic environment. These microorganisms convert organic
wastes into humus, which has significant value to agriculture farming.
Merits of the composting process
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Vermiculture
Vermiculture
is an aspect of biotechnology involving the use of earthworms as natural and versatile
bio-reactors for cleaning up the environment by adoption of cost-effective waste
management technique. Vermiculture means culturing of earthworms in a scientific
manner. It is a simple low-cost and appropriate biotechnology using earthworms
systematically. By providing them with optimum conditions for rapid multiplication
and conversion of farm wastes and bio-degradable urban wastes into bio-fertilizers,
it can preserve and improve the soil fertility.
Method of Disposal | Demerits |
Merits |
| Land Filling Open land dumping Burning/Incineration Bio-conversion into organic manure | - Restricted site availability cannot last longer - Contaminated water sources - Anaerobic gas production explosions - Environment pollution - Costly large area occupied - Increasing maintenance cost of open dumps - Ugly look to the cities & surroundings - Smoke and fire - Shifting of locations due to space becoming full - Smoke and gaseous contamination of environment - Temperature rise - Diesel costs higher - Capacity for incineration is a constraint - Technological constraints - Higher capital costs - Requires Govt. support production - Value addition to waste resource - Sustainable approach |
- Easy operation - Land gets leveled - Lower initial costs - Easy for Ragpickers - Non-skilled job - Incineration is a standard hygienic operation - Burning is easy operation - Highly useful product for land improvement crop |
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