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Leachate generation is one o f the major issues associated with open dumping o f solid waste, hi
Sri Lanka, the most common practice o f municipal solid waste handling is open dumping and
the leachate generated from these sites create serious environmental and social problems.
Therefore leachate should be treated before been discharged to the environment. When
developing a sustainable leachate treatment strategy, leachate characterization is important in
order to identify critical contaminants.
Karadiyana solid waste dump site which is located in the Western Province is the second largest
dumpsite in Sri Lanka. It receives 550 MT o f solid waste daily from 7 local authorities in
Colombo district. As this dumpsite is located in a highly urbanized and environmentally
sensitive area which is adjacent to the Bolgoda river in Piliyandala it is essential to take
measures to prevent adverse impacts o f leachate. Therefore this monitoring study was carried
out to identify the characteristics o f leachate.
Leachate samples and surface water were collected from 7 locations around the site for 10
months. Analysis was done on temperature, pH, conductivity, TDS, NO3 ', BOD, COD, and
heavy metals i.e. Cr, Zn, Cd, Pb and N i.
According to the results temperature, pH and concentrations o f NO3', Cr, Zn, Cd, Pb and N i of
all sampling locations were within the permeable levels o f Sri Lankan standards. Heavy metal
concentrations are very low which may be because this dump site only is not accepting
industrial waste. However the conductivity, TDS, BOD and COD levels o f all the locations
have exceeded the tolerance lim its significantly due to the municipal solid waste which consist
o f large portion o f organic waste. Furthermore all the parameters are higher in leachate samples
than surface water samples. This study reveals that an applicable leachate treatment system
should be introduced in order to reduce BOD and COD levels.
