Chapter Two Methods Of Solid Waste Management

Chapter 2 Methods of solid waste management

2.1 Methods

Methods of solid waste management are as follows:

• Open burning

• Dumping into the sea

• Sanitary Landfills

• Incineration

• Composting

• Ploughing in fields

• Hog feeding

• Grinding and discharging into sewers

• Salvaging

• Fermentation and biological digestion

Open burning

• Open burning refers to burning garbage in barrels, open pits, outdoor furnaces, woodstoves, or fireplaces. Open burning of garbage is much more harmful to health and the environment.

• Open burning of garbage poses health risks to those exposed directly to the smoke. It especially affects people with sensitive respiratory systems, as well as children and the elderly.

• Not an ideal method in the present day

• Layers are compacted with some mechanical equipment and covered with earth, leveled, and compacted

• With time, the fill would settle

• Microorganisms act on the organic matter and degrade them

• Decomposition is similar to that in composting

• Facultative bacteria hydrolyze complex organic matter into simpler water soluble organics

• These diffuse through the soil where fungi and other bacteria convert them to carbon dioxide and water under aerobic conditions

• Aerobic methanogenic bacteria utilize the methane generated and the rest diffuses into the atmosphere

• Too much refuse shall not be buried – fire hazard

• Moisture content – not less than 60% for good biodegradation

• Refuse depth more than 3m – danger of combustion due to compression of bottom layers – hence should be avoided

• Refuse depth is generally limited to 2m

• Temperature in the initial stages of decomposition – as high as 70 degree C – then drops

• Reclaimed areas may be used for other uses

Engineered landfill of solid waste

• Bottom of the trench is lined with impervious material to prevent the leachate from contaminating groundwater

• A well designed and laid out leachate collection mechanism is to be provided

• Leachate so collected is treated and then disposed

Open window composting

2. Mechanical composting

Open window composting

• Refuse is placed in piles, about 1.5m high and 2.5m wide at about 60% moisture content

• Heat build up in the refuse piles due to biological activity – temperature rises to about 70 degree C

• Pile is turned up for cooling and aeration to avoid anaerobic conditions

• Moisture content is adjusted to about 60%

• Piled again – temperature rises to about 70 degree C

• The above operations are repeated

• After a few days (~ 7 to 10 weeks) temperature drops to atmospheric temperature – indication of stabilization of compost

Mechanical composting

• Process of stabilization is expedited by mechanical devices of turning the compost

• Compost is stabilized in about 1 to 2 weeks

• To enrich compost – night soil, cow dung etc. are added to the refuse

• Usually done in compost pits

• Arrangements for draining of excess moisture are provided at the base of the