Arrange the following components of municipal solid waste and fossil fuel in increasing order of their higher heating value (HHV) in kJ/kg units.
A. Mixed paper B. Rubber C. Mixed plastics D. Leather E. Mixed green-yard waste
Codes

Correct option is D

Higher Heating Value (HHV) refers to the total heat released when a material is combusted, including the latent heat of water vapor. The HHV for components in municipal solid waste varies significantly due to their composition. The order of HHV is determined as follows.
1. Mixed green-yard waste E
Composed largely of moisture and organic material, resulting in the lowest HHV.
2. Mixed paper A
Made of cellulose, it has a moderate HHV, higher than green waste but lower than plastics or rubber.
3. Leather D
Contains organic and chemical treatments, providing a higher HHV than paper.
4. Rubber B
Derived from hydrocarbons, rubber has a high HHV.
5. Mixed plastics C
Plastics have the highest HHV among the listed components due to their high hydrocarbon content and energy density.
Information Booster:
1. HHV of Components:
Mixed green-yard waste: 4,500–6,500 kJ/kg
Mixed paper: 10,000–15,000 kJ/kg
Leather: 15,000–20,000 kJ/kg
Rubber: 28,000–32,000 kJ/kg
Mixed plastics: 35,000–40,000 kJ/kg
2. Moisture Content Impact:
Higher moisture content lowers HHV as energy is consumed to vaporize water during combustion.
3. Calorific Value Importance:
Helps determine the energy recovery potential of waste components.
4. Plastics as Fuel:
Plastics have the highest HHV but pose environmental challenges due to toxic emissions during combustion.
5. Rubber as Fuel:
Used in tire-derived fuel, offering high energy but requiring pollution controls.
Additional Knowledge
· Mixed green-yard waste (E)
Low energy content due to high moisture and organic material. Often composted or anaerobically digested.
· Mixed paper (A)
Includes newspapers, magazines, and cardboard with moderate calorific value. Recyclable, reducing combustion need.
· Leather (D)
High organic and chemical content gives it a higher HHV but limits its usage due to disposal issues.
· Rubber (B)
Used as tire-derived fuel, producing high energy output but requires filtration for pollutants like sulfur.
· Mixed plastics (C)
Highly calorific but problematic due to toxic byproducts like dioxins during incineration.