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Properties of Waste:
The characteristics of waste must be known in order tofacilitate the development of waste management systems.
Ø Physical Properties
Specific Weight (Density)
· It is mass per unit volume (kg/m3)
· It is very important factor in the design of a solid wastemanagement system like, storage, transportation and disposal, thedensity of solid waste varies greatly, this due to the geographicallocation, season and storage duration.
· And it often refers to uncompressed waste.
Moisture Content
is defined as the ratio of the weight of water (wet weight -dry weight) to the total wet weight of the waste. The maximumamount of moisture is recorded in food residues and the waste ofthe courtyard. Moisture content helps in generation leachate insolid waste, thus an increase in its weight and the cost ofcollection and transportation.
analysis Procedure:
Take a sample of the solid waste in a container and then weighit.
Next, place the sample in the oven in a 105 ° C temperaturefor 24 hours.
Then take the sample out of the oven and weigh it.
Calculate the moisture content using the formula shownbelow:
% of Moisture = (Wet weight- Dry weight)/ (Wet weight) x100
Particle Size and Distribution
It is necessary to know the volume and distribution of waste,this is to recover materials, especially when using trommel screensand magnetic separators.
For example, large-sized iron elements cannot be separated bya magnetic belt or drum system.
The size of waste components can be found using the followingequations:
Sc = L
Sc = (L+w)/2
Sc = (L+w+h)/3
Where
Sc = size of component, mm
L = length, mm
W = width, mm
h = height, mm
Field Capacity
It is the total amount of moisture that can be kept in thewaste sample subject to gravity withdrawal.
Field capacity is very important in identification theformation of leachate in landfills.
Permeability of Compacted Waste
Ø This property is important because it controls the movementof liquids and gases in the landfill, it is depends on Pore sizedistribution, Surface area and Porosity.
Ø Chemical Properties
Proximate analysis of flammable components of MSW includesseveral test:
· Moisture (drying at 105 oC for 1 h).
· Volatile flammable materials (It ignites when there is nooxygen at 950 degrees Celsius).
· Fixed carbon (combustible residue left after Step 2)
· Ash (weight of residue after the burn in an opencrucible)
Fusing point of ash: The temperature at which ash is generatedfrom burning waste will form a solid (clinker) Which will be formedby fusion and agglomeration.
fusing temperatures: 1100 - 1200 Co
Ultimate analysis (major elements)
· Includes the determination of percentage of C (carbon), H(hydrogen), O (oxygen), N (nitrogen), S (sulfur) and ash.
· Halogen selection is often included in the Ultimateanalysis.
· The result are used to determine the chemical composition oforganic matter in MSW they are also used to identify theappropriate mix of waste materials to achieve appropriate C/Nratios for biological conversion processes.
Energy content:
Energy content can be determined by:
By using a full scale boiler as a Calorimeter.
By using a laboratory bomb calorimeter.
By calculation.
Most of the data on the energy content of the organiccomponents of MSW are based on the results of bomb calorimetertests.
