Solid & Hazardous Waste Management

MSW Characteristics & Calorific Value

Moisture content, compaction, density and the Dulong calorific-value estimate for municipal solid waste.

PART 1

Topic Breakdown & Traps

The Engineering Principle

Designing MSW systems needs the waste's physical composition, moisture content, density and energy content. Compaction reduces volume for transport and landfilling; calorific (heating) value decides the feasibility of energy recovery and is estimated from the elemental composition by the modified Dulong formula.

The Core Formula Matrix

Moisture content (wet basis):

M C = \frac{w _{w e t} - w _{d r y}}{w _{w e t}} \times 100%

Volume reduction by compaction:

V R = (1 - \frac{ρ _{l oose}}{ρ _{co m p a c t}}) \times 100%

Modified Dulong HHV (kJ/kg):

H H V = 337 C + 1419 (H - \frac{O}{8}) + 93 S

(C,H,O,S as % mass)

Dry solids:

w_{d r y} = w_{w e t} (1 - M C)

The ‘IIT Traps’

⚠
Higher moisture lowers the net calorific value (latent heat penalty).
⚠
Compaction ratio compares densities, not volumes directly.
⚠
Use elemental %s in Dulong — and the $(H - O /8)$ correction for bound oxygen.

📚 Standard references

Integrated Solid Waste Management — Tchobanoglous, Theisen & Vigil
Solid Waste Management — C.S. Rao / S.K. Garg

PART 2

Progressive 3-Tier Question Suite

Q1MEDIUM2 Marks · NAT

1000 kg of wet MSW has a moisture content of 50 % (wet basis). The mass of dry solids is _____ kg.

Q2HARD2 Marks · NAT

Loose MSW density is 100 kg/m³ and compacted density is 500 kg/m³. The volume reduction achieved is _____ %.

Q3BASIC1 Mark · MCQ

Increasing the moisture content of municipal solid waste generally: