Abstract
A simple mathematical model (MOCLA: Model for
Organic Chemicals in Landfills) is presented, describing
the distribution of organic chemicals between leachate,
gas and solid waste. The model also predicts the fate of
the chemicals in terms of emissions with leachate and
landfill gas and in terms of degradation and transformation
in the landfill. Local equilibrium is assumed for the
distribution of the chemicals in the landfill as expressed
by Henry’s Law for the leachate-gas interface, and by the
linear partition coefficient based on the waste solid
organic carbon content for the waste-leachate interface.
Degradation of the chemicals is expressed as a first order
reaction. Annual specific leachate and gas generation
data in combination with data on landfill area and volume
allow for prediction of main emission routes. Model
simulations involving two landfill scenarios for a number
of chemicals with different physico-chemical characteristics
indicate that volatilisation is a likely route for some
chemicals (e.g. vinyl chloride, and some of the freons),
while other chemicals (e.g. phenol, lower chlorinated
aliphatic compounds) more likely will appear as dissolved
in the leachate. However, many chemicals will be strongly
associated with the solid waste (e.g. dichlorobenzene,
naphthalene, and higher Polycyclic Aromatic
Hydrocarbons (PAHs), and the pool available will be able
to supply the landfill gas and leachate with organic trace
components for decades unless these are degraded in the
landfill. The model suggests that, in addition to the physico-chemical characteristics of the organic chemical, the presence of free phases of organic chemicals and the
degradability of the chemicals are the main factors controlling the fate and emissions of organic chemicals in the landfill environment.
Original language | English |
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Journal | Waste Management and Research |
Volume | 19 |
Issue number | 3 |
Pages (from-to) | 201-216 |
ISSN | 0734-242X |
DOIs | |
Publication status | Published - 2001 |
Keywords
- gas
- degradation
- organic chemicals
- emission
- leachate
- landfill
- phase distribution