Abstract:
ABSTRACT
The presence of organic matter in drinking water sources potentially poses a considerable impact on
drinking water quality. Organic matter is problematic as it serves as a precursor to disinfection -byproducts
formation mainly trihalomethane. The goal of this work was characterized the raw water
organic matter to reduce the formation of disinfection by products while removing organic matter by
enhanced coagulation using ferric chloride and aluminum sulfate as coagulant through jar testing. To
identify naturally occurring organic matter more easily removed by coagulation or more resistant, the
organic matter in the raw water was analyzed in the dry and wet seasons. water quality parameters
including pH, turbidity, alkalinity, color, total organic carbon, ultraviolet absorbance at the wave
length 254 and specific ultraviolet absorbance were analyzed. The result of specific ultraviolet
absorbance show that the organic matter is characterized by hydrophilic, low molecular weight and
low humic. The result showed that pre chlorination, polyelectrolyte, and aluminum sulfate-based
conventional coagulation found less efficient in minimizing the presence of natural organic carbon to
prevent disinfection by product. Because natural organic matter is hydrophilic, treatment with
increased coagulation considerably improves natural organic carbon removal, but leaves behind a
large proportion of natural organic matter.
By using ferric chloride which reduces total organic carbon levels by 38% in the winter and 53% in
the summer and alum which reduces Ultraviolet absorbance at the wave length 254 levels by 19% in
the winter and 50% in the summer, the enhanced coagulation process improved the removal of
natural organic carbon mean less trihalomethane formation. On average, there is 9% more removal
of natural organic carbon in the winter and 25% more removal of Ultraviolet absorbance at the wave
length 254 in the summer compared to the current treatment technique.
By increasing the coagulant dose it is possible lowering the organic precursor and chlorine requirement,
the content of trihalomethanes can be reduced. This indicated that enhanced coagulation process is
somewhat effective means for removing hydrophilic organic matter present in drinking water if the
coagulant dose and pH condition are adjusted to optimum condition.
Key words: Enhanced Coagulation, natural organic Matter, Total Organic Carbon, Disinfection by prodaction