Tuesday, January 14, 2014

Disposal of Solid Wastes and Refuse of society

Hello there,

What is Refuse?

All solids and semi-solid wastes of community , except human excreta and sullage is called refuse. It includes garbase, ashes, rubbish, dust etc.


It includes liquid wastes from the bath rooms, kitchen sinks, wash basins etc.
  • Garbage are putrescible organic wastes includes food articles, vegetable peelings, fruits peelings etc. When it is scientifically processed and composted, then it is possible to obtain valuable products, like grease, hog wood, fertilizer etc. Garbage normally weighs 450 to 900 kg/m3.
  • Ashes are incombustible waste products(700 to 850 kg/m3).
  • Rubbish: It includes all non-putrescible wastes except ashes. It includes paper, glass, rags, etc. (50 to 400 kg/m3).
The usual weight of refuse varies between 300 to 600 kg/m3.
In an average modern city, each citizen produces about 0.3 to 0.8 kg of solid domestic waste per day.

Disposal of REFUSE

  • By Sanitary Land Filling
In low lying area, the refuse is filled up or dumped in layers of 1.5 m or so, and each such layer is covered by good earth of at-least 20 cm thickness so that refuse is not directly exposed. If the thickness of land-filling is large filling shall be done in layers, and each layer shall be left out for at-least seven days, and compacting by movement of bull, motors trucks etc. for its settlement, before starting filling the second layer of refuse.
  1. The land-filling operation is essentially a biological method of waste treatment, since the waste is stabilized by aerobic as well as anaerobic process.
  2. The refuse get stabilized, generally within a period of 2 to 12 months, and settles down by 20-40% of its original height.
  3. This method is widely adopted in our country. 90% of Indian refuse is disposed off in this manner. 
  4. Sanitary land fills may cause troubles during peak monsoons.
  5. Leachate is a colored liquid, that comes out of sanitary land fills.
  6. Quantity of refuse produced in an average Indian city or a town is of the order of 1/4 to 1/5 heefare/day.
  • Burning or incineration: In this method this is fired.
  • Burying it into the sea(obselete method)
  • Pulverization
  • By Composting 
Composting of refuse is a biological method of decomposing solid wastes. This decomposition can be effected either under aerobic conditions, or under anaerobic conditions, both. The final end product is a manure, called compost or humus.
In India following two methods are adopted:
  1. Indoor method: It uses manual turning of piled up mass(refuse and night soil) for its decomposition under aerobic conditions
  2. Bangalore method: It is primarily anaerobic in nature; This method is widely adopted by municipal authorities throughout the country. The refuse and night soil, in this method are therefore piled up in layers in an under-ground earthen trench(10cm*1.5cm*1.5cm). This mass is covered at its top by layer of earth of about 15 cm depth, and is finally left over for decomposition.
Thanks for visiting!

Reference: GK Publishers, GATE 2013