landfill gas

1. Landfills Gas Generation and
collection in landfills
S.M.Hasan Razu, Store Officer, CPS, Raozan, BPDB, Raozan.
Ex-Assistant Manager (Environment, Safety and Total Quality Management), Matarbari Power Plant, CPGCBL, Ministry
of Power, Energy and Mineral Resources.

2. What is Land fill ?
• Ultimate disposal of solid waste
• Land fill may be defined as the
operation in which waste to
disposed of are compacted in
layers and covered with a layer
of earth at the end of each day’s
operation.

3. • Complete disposal method
• Composting or incineration
method needs landfill
• Landfill involves the
application of basic
engineering techniques.

4. • Drawbacks
• Organic substances returing
to groundwater and
surfacewater resources
• Inorganic substances returing
to groundwater and
surfacewater resources
• Pathogenic micro organism
Organic substances returing
to groundwater and
surfacewater resources

5. • The Planning, Analysis and design of sanitary
landfill system involve the application of a
variety of scientific, engineering, economic
and environmental principles
• Factors Considered for
design and operation of
landfill
1. Landfill Site selection
2. Landfilling Methods and Operation
3. Design of Landfill
4. Gas and leachate in Landfill
5. Operation of Landfill
6. Environmental Factors

6. • Landfill site Selection
 Sufficient land area
 Minimum Haul distances are desirable
 Cover material should be available at or near the
landfill site.
 Climatic conditions to be considered like wind pattern
and local surface water hydrology
 Geologic and hydrologic conditions being the most
important factors.
 Environmentally acceptable with respect to noise,
odour, dust and vector control

7. Landfilling methods and operation
• Selection of a method depends upon
the physical conditions of the site,
amount and types of solid waste to be
disposed.
• Two Methods of Landfilling
 Trench method
 Area Method

8. Trench Method
 Excavation of a trench.
 Dumping of waste then
placed in to the trench,
spread and compacted.
 Excavating soil serving as a
cover material
 Narrow trench width would
require less cover material
• Sufficient width should be provided in
order to allow discharge of the wastes
as well as accommodate the
compaction equipment and vehicles
that use the fill.
• Width of the trench should be twice
that of the largest piece of
equipment that will work in the
trench.
• The Trench method is suitable for
sites which have a flat or gently
rolling land surface, a low
groundwater table and a thick soil
layer.

9. Trench Method

10. Area Method Of Landfilling
• Not involving excavation of
trench.
• Waste are spread and
compacted on the surface
of the ground.
• Cover material is then
spread and compacted
over the layer of waste.
• Suitable for flat and gently
sloping land and where the
groundwater table is high.

11. Design of Landfill
• Designing determinants
quantity,
-rate of delivery,
-characteristics of solid
waste
- operating practice.
• Size of the site must
include two important
factors
1. Gross Area_ Total area
within the boundary
2. Useful fill area_50-80%
of the gross area

12. • A cell is built by spreading
and compacting of solid
waste into layers within a
confined area.
• The compacted waste and
its daily soil cover make up
a cell.
• A series of adjoining cells at
the same elevation
constitute a lift.
• A completed fill may
consist of one or several
lifts.

13. • The basic element of a cell
are height, length, width of
working face, slope of side
walls and thickness of daily
cover.
• Cell heights vary between 2
and 4 meters

14. Leachate and gas in landfills
• What is leachate?
 Landfill leachate is a high organic matter and
ammonium nitrogen strength wastewater
formed as a result of percolation of rain-
water and moisture through waste in landfills.
 Key factor for in safe landfill design and
operation

15. Why leachate detrimental to the surface
water & Ground water source?
High BOD
High COD
High Turbidity
High TDS
High TSS

16. Leachate collection system
 Perforated piping system to
collect and carry the
leachate to a storage tank
• Leachate disposal methods
 wastewater treatment
plant
 Onsite treatment

17. Landfill Gas!!!
 A Mixture of methane and
carbon di-oxide produced
by the decomposition of
organic matter in the solid
waste.
 Landfil gas is highly
flammable and poses a risk
of explosion if not properly
managed
• A low cost design to handle
landfill gas may consist of
buried vertical perforated
pipes to collect the gas,
using its natural pressure
and vent or flare it at the
surface.

18. Landfill Operation
• Important Operational
Procedures
 Site Preparation and
Maintenance
 Environmental Control
 Operating Hours
 Operations under inclement
weather conditions