Disinfection by-products in drinking water – a case study on Calgary, Alberta, Canada

Abstract

Disinfection by-products (DBPs) have been monitored in Calgary's drinking water for approximately 15 years. The variability of the DBPs has typically exhibited similar patterns over the period of monitoring. Due to the nature of the surface waters supplying the water treatment plants, the level of DBPs was largely influenced by surface runoff events where the level of natural organic matter (NOM) increased, which was characterized by a relatively high total organic carbon (TOC) content. Principal component analysis (PCA) was utilized for this study to quickly identify the key underlying correlations present within the very large, complex multivariate data matrix. Apart from TOC, chlorine demand, chlorine residual and temperature were observed to correlate with the formation of DBPs in the finished drinking water. In addition to TOC, PCA also indicates that pH and temperature in the distribution system could have an influence on the variability of DBPs in Calgary's drinking water. It was apparent that upgrades to the water treatment systems in Calgary have resulted in an improved removal of DBP precursors such as NOM prior to chlorination, which is a key factor in reducing the DBP levels in the drinking water, thereby providing an enhanced level of public health protection.

Applications of biofiltration in drinking water treatment – a review

“…In drinking water treatment, natural organic matter (NOM) is responsible for imparting colour to the water. If left untreated throughout the treatment process, NOM is a potential disinfection by‐product precursor in the presence of certain disinfectants; such as chlorine . Biofiltration with or without ozonation is effective in reducing the NOM content in the water source through mineralization of NOM by the microbes in the biofilm contained within the biofilter …”

Water Quality Correction Within Water Distribution System

“…The phenomenon of secondary water contamination in water supply systems widely appears around the world [4][5][6][7][8]. Causes of this phenomenon have different reasons, and factors affecting water contamination can be divided into several groups connected with: water, its treatment and entering into the water supply system, hydraulic conditions, and pipe age in water distribution system, piping material, and network structure [9][10][11][12][13][14].…”

Secondary contamination in Polish drinking water

“…Causes of this phenomenon have different basis, appear individually as well as coexist and overlap, worsening the quality of distributed water. Factors that influence the water contamination can be divided into several groups: connected with water (ignored in the presented paper), network's hydraulic, period and quantity of exploitation, material and sealing of pipes as well as connected with the network's structure [4][5][6][7][8][9]. Mentioned factors do not always individually affects the quality of water distributed by water supply network, but often one factor implicates changes of quality in many others impact areas [10].…”