Solid Waste Management
Treatment and Disposal
1. Sanitary Landfill
• Important aspects in the
implementation of sanitary landfills;
– Site selection
– Land filling methods and operations
– Occurrence of gasses and leachate
Available land area Site should have a useful life greater than 1
yr (minimum value)
Haul distance Will have significant impact on operating
Soil conditions and topography Cover material must be available at or near
Surface water hydrology Impact drainage requirements
Geologic and hydro geologic conditions Probably most important factors in
establishment of landfill site, especially
with respect to site preparation.
Climatologic conditions Provision must be made for wet weather
Local environment conditions Noise, odour, dust, vector and aesthetic
factors control requirements.
Ultimate use of site Affects long term management for site
Landfill Methods and Operations
• A plan of operation for the placement of
solid wastes must be prepared.
• The principal methods and operations:
– Area method
– Trench method
Occurrence of Gases and Leachate
Figure: Cross section of a closed sanitary landfill
Anatomy of a sanitary landfill
• Gases found in landfills include air,
ammonia, carbon dioxide, carbon
monoxide, hydrogen, hydrogen
sulphide, methane, nitrogen and
• Leachate in landfill may be defined as
liquid that has percolated through solid
waste and has extracted dissolved or
suspended materials from it.
Type of Composting
• Backyard composting.
• Yard trimmings composting.
• Mixed MSW composting.
• Thermal conversion products that can be
derived from solid wastes include heat,
gases, a variety of oils and various related
Types of incinerators
• ROTARY KILN
• FLUIDIZED BED
• LIQUID INJECTION
• MULTIPLE HEARTH
• CATALYTIC COMBUSTION
• WASTE-GAS FLARE
4. Pyrolysis and Gasification
• Pyrolysis is the thermal decomposition of organic
material at elevated temperatures in the absence
of air or oxygen.
• Gasification is a special type of pyrolysis where
thermal decomposition takes place in the
presence of a small amount of oxygen or air.
– The gas which is generated can then be burned in
industrial boilers or cleaned up and used in
combustion turbines for electric generators
• Pyrolysis and gasification are thermal processes;
– use high temperatures to break down any waste containing
– use less oxygen than traditional mass-burn incineration.
– pyrolysis process degrades waste to produce char (or ash),
pyrolysis oil and synthetic gas (called syngas).
– gasification process then breaks down the hydrocarbons left
into a syngas using a controlled amount of oxygen.
• Gasification and pyrolysis typically rely on carbon-based waste
such as paper, petroleum-based wastes like plastics, and
organic materials such as food scraps
5. Wet Oxidation
• Process of an oxidation reaction that
occurs in liquid water.
• The water is an important component of
the reaction process. Wet oxidation
reactions do not occur in the gas phase
and elevated pressure is required to
maintain water in the liquid phase.
• Because the liquid is not vaporized, wet
oxidation requires less energy for auto-thermal
operation than incineration.
• Nitrogen and sulfur, when present, are not
released as gaseous NOx or SOx but remain in
solution as environmentally acceptable nitrate
• The hydrocarbons are converted to CO2 and
• Oxidation is rarely complete so a portion of the
organic COD remains as readily biologically
treatable organic acids, such as acetic acid
• The purpose of the wet oxidation
– to destroy the biologically untreatable high
molecular weight branched molecules in
the POE stream.
– to reduce the high organic loading going
to the PACT biological system from the
ACC stream by first destroying most of
that COD content.