Increasing levels of nitrate in receiving waters have been becoming
serious issues worldwide due to the intensive application of fertilizers
and pesticides, and sewage irrigation. The high concentration of nitrate
has the potential risks of eutrophication and toxic algal blooms in receiving
waters (Ghafari et al., 2008). Nitrate is identified as one of the
hazardous contaminants in drinkingwater because it can cause infantile
methemoglobinemia (blue baby syndrome) and reduction of nitrate
into nitrites in saliva might induce the formation of nitrosamines,
which are known carcinogens (Matiju et al., 1992). The maximum admissible
concentration limit of nitrate in drinking water is 10 mg L−1
as nitrate-nitrogen (NO3-N) set by the US Environmental Protection
Agency and 50 mg L−1 as nitrate by World Health Organization to reduce
the risks to human health (Tsai et al., 2004).