Abstract

The previous research on the occurrence of disinfection by-products (DBPs) in drinking water has focused on trihalomethane (THMs) formation and evolution, in particular within distribution systems. In this study, the variability of occurrence of haloacetic acids (HAAs) before and after treatment was investigated. The investigation focused on point–to-point fluctuations of HAAs in different treatment stages within the treatment plant. The research was also carried out to find out the possible sources for the presence of HAAs before chlorination in the raw water. The results showed that the presence of HAAs from the raw water point until the filtered water occurred due to industrial waste and sewages. Subsequent formation of HAAs from treated point until service reservoir due to disinfection. The HAAs concentration was the highest and most variable in the plant where level of DBP precursor indicators and the chlorine dose were both higher. However, HAAs level and in particular dichloroacetic acids (DCAA) (the preponderant HAAs species in the waters under study), trichloroacetic acids (TCAA) decreased dramatically during filtration, very probably because of the biodegradation within the filter. An ANNOVA test was used to evaluate the level of significance of HAAs between treated water and service reservoir outlet water.

Highlights

  • Chlorination is a widely used disinfection method in Malaysia because of its properties of odour removal, high oxidation potential, economy and efficiency

  • Lime is introduced in the filtered water and that leads to increase in pH which results in an increase in dichloroacetic acids (DCAA) and a decrease in trichloroacetic acids (TCAA)

  • This study aimed to investigate variations of haloacetic acids (HAAs) within treatment plant where river water is not pre-chlorinated before subsequent physico-chemical treatment

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Summary

Introduction

Chlorination is a widely used disinfection method in Malaysia because of its properties of odour removal, high oxidation potential, economy and efficiency. This “traditional” disinfection process has been recognized as one of the greatest public health achievement of the millennium. The chlorination of water history begins in the 18th century where John Snow was the first person who used chlorine to treat the water at Broad Street Pump in Soho, London after a cholera outbreak in 1850 This life-saving technology has served the water supply well for a century providing disease-free tap water to public. The drinking water standard of HAAs known as maximum contaminant level has not yet been regulated in Malaysia. The USEPA [3] sets maximum contaminant

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