Trihalomethanes precursors removal by using simultaneous coagulation - disinfection

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Date
2019-06
Authors
Nur Fariha Binti Ismail
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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
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