Affordable Water Filtration Technology for Small Rural Communities

Zhang, He and Tafvizi, Hoda and Husain, Tahir and Chen, Yuan (2017) Affordable Water Filtration Technology for Small Rural Communities. Research Report. Memorial University of Newfoundland, St. John's, Newfoundland and Labrador.

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Abstract

Chlorine has been commonly used as disinfectant and oxidant in the drinking water supply systems due to its germicidal potency, efficiency, and low cost. Chlorination process not only removes odour, color, and certain metals, but also kills pathogens that usually grow in the pipelines. However, chlorine can react with natural organic matter (NOM) and produce compounds known as disinfection by-products (DBPs). Different water treatment processes have been applied to remove NOM before it reacts with chlorine to form DBPs. However, traditional water treatment methods showed limited capability in NOM removal. Activated carbon is identified as the best available technology and has been applied for NOM removal because of its high affinity to organic matters even at low concentrations. In this study, a column filtration technology utilizing activated carbon as a barrier was developed and applied in the treatment of source waters collected from three local communities. TOC, as a NOM indicator, is identified more reliable than UV since the UV reading can only reflect the amount of light-sensitive organic matters. Batch test results demonstrate the use of 0.5 g (AC) /L (water) has the highest adsorption effectiveness and lowest cost of AC. Meanwhile, column filtration results indicate the activated carbon barrier is effective to remove 64, 77 and 74 percent of NOM from the source water of Sunnyside, New-Wes-Valley and Salvage, respectively. The follow-up chlorination experiment illustrates that the formation of THMs and HAAs can be considerably reduced after the water passed through the column. NOM fractionation of Sunnyside and New-Wes-Valley source water were also discovered; it is found the New-Wes-Valley source water contains higher amount of hydrophobic fraction which can result in the higher concentrations of THMs and HAAs in the disinfection process. This is proved in the chlorination experiments by assessing the formation potential of THMs and HAAs. The fractionation result can help to predict that the concentration of low molecular size NOM in New-Wes-Valley is higher than that in Sunnyside. Above all, the cost-effective carbon filtration technology developed in this study can be potentially applied as a pre-treatment technology for intake source waters for the local communities.

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