Abstract:
Water treatment plants generate large quantities of sludge resulting from treatment processes.
“Konduwatuwan” water treatment plant located in Ampara in Sri Lanka, generates a huge amount of
sludge annually and is disposed directly to the adjacent environment. Concerns have been raised by
various authorities regarding the potential risk of the sludge on human and environmental health. This
study was conducted to characterize the sludge and to evaluate the potentials to utilize it for soil
application in agriculture. Physical and chemical parameters were analyzed using sludge samples in
the laboratory. The result showed that the average moisture, total solid, ash and organic matter
contents present in the sludge were 79.44%, 20.55%, 60.73% and 39.27% respectively and the monthly
mean values of ash and organic matter contents did not significantly vary with time during the study
period. The pH, electrical Conductivity, levels of cadmium, chromium, iron, lead and nitrogen were
promising in the sludge when compare with aluminium based water sludges used for comparison in this
study. Further, the levels of pH, electrical conductivity, nitrogen and phosphorous present in the sludge
were within the suitable range for land application and the concentrations of cadmium, chromium and
lead were far below the threshold values for composting according to Sri Lankan standards. Thus, the
sludge can be utilized for the cultivation of non-food crops. However, further studies are recommended
to investigate the effects of sludge on long-term application over the metal loading on cropping lands.
