N[H.sub.4]-N removal through nitrification and hydrogenotrophic denitrification in simple attached growth reactors

• Published in: Water, air, and soil pollution Vol. 223; no. 7; p. 3939
• Main Authors: Khanitchaidecha, Wilawan, Shakya, Maneesha, Tatsuru, Kamei, Kazama, Futaba
• Format: Journal Article
• Language: English
• Published: Springer 01.09.2012
• Subjects: Denitrification; Nitrification; Water, Underground
• ISSN: 0049-6979
• DOI: 10.1007/s11270-012-1162-0

To provide good quality of drinking water, a biological system to remove ammonium-nitrogen (N[H.sub.4]-N) from groundwater was studied in this research. The N[H.sub.4]-N removal system consists of two attached growth reactors: one for nitrification and the other for hydrogenotrophic denitrification (H. denitrification). The nitrification reactor, fed by the N[H.sub.4]-N contained water, could remove N[H.sub.4]-N without any need of aeration. The nitrification efficiency was increased by reactor length; the highest efficiency of 92 % was achieved at the longest reactor of 100 cm. A high Fe in groundwater affected the reactor performance by decreasing the efficiency, while a low inorganic carbon (IC) had no effects. Despite of good efficiency in terms of N[H.sub.4]-N removal, the nitrification reactor increased the concentration of N[O.sub.3]-N in its effluent. To treat the N[O.sub.3]-N, a H. denitrification reactor was set up after the nitrification reactor. Efficiency of the H. denitrification reactor was enhanced by increasing [H.sub.2] flow rates. The efficiencies were 3,27, and 90 % for 30, 50, and 70 mL/min of [H.sub.2] flow rates, respectively. It was also found that the N[O.sub.3]-N contained water (water from the nitrification reactor) had to supply IC (i.e., NaHC[O.sub.3] or C[O.sub.2]) for efficient H. denitrification; however, an on-site reactor showed that it can be achieved even without IC addition. The treated water contained low N[H.sub.4]-N and N[O.sub.3]-N of <1.5 and <11.3 mg/L, respectively, which comply with drinking water standards. The good performance of the reactors in terms of high efficiency, no aeration need, and low [H.sub.2] supply indicated appropriateness of the system for groundwater treatment. Keywords Attached growth reactor * Nitrification * Hydrogenotrophic denitrification * Groundwater * N[H.sub.4]-N removal