Handling and Processing Waste

Waste Management Technology Vol 1-Handling and Processing Waste

SNI19-3964-1995 categorizes the composition of waste into nine types; see Chapter 2, plus groupings for hazardous waste. When associated with handling and processing, grouping based on composition can be divided into:

  • Putrecible waste and non-perishable waste.
  • Organic and inorganic waste
  • Biodegradable and non-biodegradable waste.
  • Combustible and non-combustible waste.
  • Recyclable and non-recyclable waste.
  • Hazardous and non-hazardous waste.

Table 1: The possibility of handling and processing waste based on its composition

Table 1: Waste handlingand processing based on composition.



Handling and processing


Food waste

Putrescible, organic, biodegradable and combustible


Wood, leaves, garden waste

Organic, biodegradable and combustible


Paper and cardboard

Biodegradable, combustible and recyclable.


Textiles and textile products

Biodegradable (natural material textiles), combustible and recyclable.


Rubber and leather

Biodegradable (natural material textiles), combustible and recyclable.



Combustible and recyclable


Iron and other metals






Hazardous waste

Must be dealt with immediately


Others: inert materials

Only land-fill

A more thorough analysis of the type of waste treatment can be done based on its characteristics, namely:

  • The maximum amount of waste that can be biologically treated is based on the percentage of volatiles (550°C) it contains. The maximum ash produced when waste is burned at 550°C is = total dry weight (solids) minus volatile content at 550°C.
  • Microorganisms only consume organic carbon (Corg). Most of the volatiles are organic carbon. So if there is organic carbon data, then the maximum weight of waste that can be biologically degraded is calculated based on the organic content it contains. If, for example, the Corg value is 50% (dry weight) with a waste moisture content of 60% (wet weight), then the biological process will only be able to reduce the waste weight at most (100%–60%) x 50% = 20% (dry weight). If the Corg value at the end of the process is 0, it means that there is no more residue in the form of compost from the aerobic process or slurry from the anaerobic process, and this is impossible to achieve. See the explanation in Sub-Chapter Biodegradation of Waste Material.
  • The maximum amount of waste that can be treated by incineration is based on the percentage of loss-of-ignition (850°C) it contains. loss-of-ignition (850°C) that it contains, i.e., the amount of waste that is lost when burned at 850°C.

A more detailed analysis can be based on the constituent elements, namely C, H, 0, N, S, P, Cl, Br, and I. Analyze the waste chemical formulas as described in the example below.

Segregation is the process of handling waste in a mixed manner with the aim of obtaining more uniform materials or materials that are still of economic value and recyclable, or to facilitate further handling. Some sorting techniques are outlined below, such as air sorting, magnetic sorting, density sorting, the use of tires, and the use of belt conveyors.

Example 1:

Based on the survey, the composition of waste (% weight-wet) is as below:

1.     Rubbish and food waste                         = 55,60

2.     Wood, leaves, garden waste                   = 3,50

3.     Paper and cardboard                               = 13,12

4.     Textiles (natural)                                     = 1,37

5.     Rubber and leather (synthetic)                = 3,12

6.     Plastics                                                    = 18,70

7.     Iron and other metals                              = 0,02

8.     Glass                                                       = 1,26

9.     Hazardous waste                                    = 1,40

10.    Others                                                     = 2,35

Analysis: how to handle it based on composition


·     Easily decomposed waste = 55.60% (must be transported and handled immediately).

·   Organic waste = 55.60+3.50 = 58.66% (must be transported and handled immediately).

·   Biodegradable waste = 55.60+3.50+13.12+ 1.37 = 73.15% (the maximum that can be treated biologically).

·  Combustible waste = 55.60+3.50+ 1.12 +1.37+ 18.7 = 94.97% (the maximum amount that can be treated by a thermal process).

·  Recyclable waste = 13.12+1.37+3.12+18.70+0.02+1.26 = 37.57% is the maximum that can be recycled beyond composting.

·    Hazardous waste = 1.40% (requires special handling).

·    Minimum waste to be landfilled = 2.35%.

Example 2:

The characteristics of waste entering a TPS are:

1.     Moisture content = 63.3% (wet weight)

2.     Volatile content = 77.8% (dry weight)

3.     Organic carbon content = 44.7% (dry weight)

4.     Fixed carbon content = 3.9% (dry weight)

Analysis: reduction of 100 kg (wet weight) of waste by biological and thermal processes.


a)     Water weight = 63.3 kg. Weight of dry solids: 36.7 kg.

b)    Volatile weight = 0.778 x 36.7 kg = 28.6 kg, which is the       maximum weight degraded.

c)  From the organic content, the maximum amount of waste that can be treated biologically is 0.447 x 36.7 = 16.4 kg. This process will not reduce the weight of the water.

d)  Waste reduction from 8S0°C combustion (loss-of-ignition) = (77.8% + 3.9%) x 36.7 kg = 29.98 kg. This process will evaporate the contained water.

Example 3:

The results of the analysis of waste characteristics are:

a)    Moisture content = 27.6% (wet weight).

b)    Volatile content = 74.42% (dry weight).

c)     Carban C = 48.35% (dry weight).

d)    Hydrogen H = 6.31% (dry weight).

e)    Oxygen O = 38.37% (dry weight).

f)      Nitrogen N = 1.23% (dry weight).


Determine the chemical formula of the waste sample.


100 kg of wet waste will contain:


a)    Water = 0.276 x 100 kg = 27.60 kg.

b)    Dry solids = (100 - 0.276) x 100 kg = 72.40 kg.

c)     Carban C = 0.483 x 72.40 kg = 34.97 kg.

d)    Hydrogen H = 0.0631 x 72.40 kg = 4.57 kg.

e)    Oxygen O = 0.3837 x 72.40 kg = 27.78 kg. 

f)      Nitrogen N = 0.0123 x 72.40 kg = 0.89 kg. 

g)    Atomic weight: C = 12; H = 1; 0 = 16; N = 14.

If other elements are ignored, the molarity of the material is:

a)    Carban C = 34,97/12 = 2,91.

b)    Hydrogen H = 4,57/1 = 4,?7. 

c)     Oxygen O = 27.78/16 = 1.74. 

d)    Nitrogen N = 0.89/14 = 0.064.

Nitrogen is the lowest value and is positioned at 1, so the other molars, when divided by 0.064, will be obtained: C = 45.5 H = 71.4 02 = 27.2.

Thus, the chemical formula of the material is C45.5 H71.4 O27.2 N.

1. Sorting with an air classifier:

The purpose of sorting waste with an air classifier is to separate the lighter part of the waste from the heavier part. The principle of this sorting is identical to that of water treatment, which utilizes the difference in specific gravity in fluid flow. The principle is that the lighter materials will be captured and carried in the upward airflow, while the heavier ones will go down, unable to be carried upward by the airflow. This process is usually carried out with a cyclone equipped with a box to catch the descending particles, while the outgoing air is filtered and removed.

2. Sorting with a magnetic separator:

It is commonly used in industry on the principle that magnets are able to attract the type of metal in the magnetic field emitted. There are two applications of waste segregation that can be applied, namely:

  • Purify the mixed waste supply containing metals. The metal-containing part of the waste will stick to the installed magnetic field, while the non-metal-containing part of the waste will escape, not sticking to the magnetic field.
  • Purify metal mixtures by the principle of different attraction to different types of metals (ferrous and non-ferrous), so that it will be able to separate the relatively strongly attracted metal parts from the moderately or weak ones.
3. Sorting with a jig separator:

Plastic is one of the important mixed materials to be separated. One of the technologies that can be used to sort plastic types from mixtures such as PET and PS is this tool. Jigging is an old method that can achieve good separation, even with close specific gravity. If the mixture has a large specific gravity difference, the amount of separation will increase. Large particles are easier to process, and the larger the density range, the easier the separation. This technique allows separation by size difference and is generally more effective for coarse particles.

4. Use of conveyor belts:

To anticipate the large quantity of waste that must be sorted, a mechanical device is needed, such as a belt conveyor. This tool still requires human labor to sort waste. If the worker is only on one side of the conveyor belt, the width can be smaller than if there are workers on both sides. This equipment can be equipped with other automatic equipment, such as a magnetic separator, a baling press, and others. The width of the conveyor belt must be planned so that the sorting process can run optimally. When sorting manually, the walking speed needs to consider the speed of the workers in sorting the waste.

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