[Hydrogenotrophic denitrification of water using zero valent iron Nano particles]

ABSTRACT

Nitrate is a water contaminant that can cause health problems in human and animals, in addition to eutrophication of the water body. So, Nitrate-contaminated water may be treated by treatment systems. In this study, hydrogenotrophic denitrification using hydrogen produced by Fe[0] as an electron donor to nitrate removal was evaluated to assess the feasibility of employing Fe[0] in the biological nitrate treatment. Batch experiments were conducted using 250 ml amber bottles at 20-35°C under anoxic conditions. The nitrate concentration in each reactor was 20 mg N/L and triplicate samples were prepared for the following treatment Fe[0] plus cells, Fe[0] only, and control. The effect of Fe[+2] and temperature on nitrate reduction was evaluated. 97 percent of Nitrate was reduced within 2 day in a Fe[0]-cell reactor, while only 30% of the nitrate was abiotically reduced over 2 day at 30°C. Fe[+2], which is produced during anaerobic iron corrosion in the Fe[0]-cell system, might act as an electron donor for nitrate. Abiotic reduction and microbial reduction of nitrate was significantly affected by temperature conditions. The reduction rate decreased as the temperature deceased. This study demonstrated the potential applicability of employing Fe[0] as a source of electrons for biological nitrate reduction. Use of Fe[0] for microbial nitrate reduction can obviate the disadvantages associated with traditional biological denitrification that relies on the use of organic substrates or explosive hydrogen gas