Trihalomethanes precursors removal by using simultaneous coagulation - disinfection
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Date
2019-06
Authors
Nur Fariha Binti Ismail
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Abstract
Water is the most important component in our evolution and daily lives. Depletion of
clean water supply due to presence of toxic chemicals and harmful bacteria may expose
living things to waterborne diseases caused from the consumption of contaminated water.
Disinfection in drinking water has significantly reduces the risk of pathogenic diseases
but may cause chemical threat to human health due to disinfection by-products (DBPs)
formation in the presence of natural organic matter (NOM) in water. The presence of
NOM had caused many problems in drinking water, which can be removed by several
treatment options such as coagulation. The main objective of this research is to study the
ability of DBPs precursors removal when combining coagulation and disinfection
process. This study was divided into two parts; the first part involved the effectiveness
of ferric-based coagulant for coagulation process while the second part involved the
THMs precursors removal and possible THM formation when using simultaneous
coagulation and disinfection (chlorine and chlorine dioxide). Selected water quality
parameters such as turbidity, UV254, and colour were tested for raw and treated water
samples to observe the DBPs precursors removal. The coagulant used in this study was
ferric chloride (FeCl3) while chlorine (Cl2) and chlorine dioxide (ClO2) were used as
disinfectants. Based on the study, the highest percentage of turbidity removal was
99.74% with FeCl3 dosage at 20 mg/L and pH condition 5.0. Best UV254 removal was
achieved at 20 mg/L FeCl3 dosage with pH condition 5.0 (55.68% removal). The
optimum colour reduction was found to be 82.59% at pH 5.0 with FeCl3 dosage of 20
mg/L. FeCl3 was proven to be a better coagulant with pH condition 5.0 in removing
DBPs precursors, when used alone. According to the result from the second part of this
study, the combination between FeCl3 as coagulant and Cl2 as disinfectant had the highest
turbidity and UV254 removal at 99.74% and 55.68% respectively