Abstract:
Odours emitted from Municipal Solid Waste (MSW) landfills create nuisance in the
surrounding environment. The odour comes from the mixture of volatile organic
compounds present in the landfill gas, leachate and leachate treatment systems, sewage
sludges and waste materials. The research objective is to develop an Odour Impact
Model (OIM) to quantify the impact of odour from a landfill on the surrounding
communities. The model provides a basis for site planning and odour regulations.
A suitable OIM has been developed with special emphasis on quantifying emissions
from the source. A micrometeorological model has been developed based on the
estimation of footprints of scalar odour concentration measurements in the atmospheric
surface layer. A simple experiment has been designed based on this model. The results
of this model have been compared with those from the direct emission measurement
approach using a portable Lindvall Hood. Major advantages of the indirect
micrometeorological approach are the simplicity of the experiment design, and its
ability to cover various spatial resolutions.
The commercial software MPTER/COMPLEX-I and UK-ADMS have been used to
predict the dispersion of odour around two solid waste sites. UK-ADMS uses a better
representation of short-range dispersion (considering plume meandering and in-plume
fluctuations) and is thus likely to be more accurate close to the source. The two models
compare well at distances greater than 500 metres downwind from the source. The
perception recorded in the surrounding community has been analysed with four
psychophysical models to validate the impacts predicted by the suitable dispersion
model. The model based on Weber-Fechner law describes the relationship between
odour intensity and odour concentration (ou/m3) very well for the less intense odour
samples, while Laffort’s equation expresses a better relationship with more intense
odour samples.
The main strength of the integrated OIM is its ability to handle the problem of odour
nuisance from solid wastes quantitatively. Amongst the major weakness was poor
validation due to lack of sufficient data. Successful use of the OIM will require
measurements which account for the extreme variations in surface conditions, cover
type, waste composition, wasteage and subsidence.
