TY - JOUR
T1 - Remediation of nitrate-nitrogen contaminated groundwater by a heterotrophic-autotrophic denitrification approach in an aerobic environment
AU - Huang, Guoxin
AU - Fallowfield, Howard
AU - Guan, Huade
AU - Liu, Fei
PY - 2012/9
Y1 - 2012/9
N2 - A novel heterotrophic-autotrophic denitrification (HAD) approach supported by mixing granulated spongy iron, methanol, and mixed bacteria was proposed for the remediation of nitrate-nitrogen (NO 3-N) contaminated groundwater in a dissolved oxygen (DO)-rich environment. The HAD process involves biological deoxygenation, chemical reduction (CR) of NO 3-N and DO, heterotrophic denitrification (HD), and autotrophic denitrification (AD). Batch experiments were performed to: (1) investigate deoxygenation capacities of HAD; (2) determine the contributions of AD, HD, and CR to the overall NO 3-N removal in the HAD; and (3) evaluate the effects of environmental parameters on the HAD. There were 174, 205, and 2,437 min needed to completely reduce DO by the HAD, spongy iron-based CR, and by the mixed bacteria, respectively. The HAD depended on abiotic and biotic effects to remove DO. CR played a dominant role in deoxygenation in the HAD. After 5 days, approximately 100, 63.0, 20.1, and 9.7 % of the initial NO 3-N was removed in the HAD, HD, AD + CR, and CR incubations, respectively. CR, HD, and AD all contributed to the overall NO 3-N removal in the HAD. HD was the most important NO 3-N degradation mechanism in the HAD. There existed symbiotic, synergistic, and promotive effects of CR, HD, and AD within the HAD. The decrease in NO 3-N and the production of nitrite-nitrogen (NO 2-N) and ammonium-nitrogen (NH 4-N) in the HAD were closely related to the C to N weight ratio. The C to N ratio of 3.75:1 was optimal for complete denitrification. Denitrification rate at 27.5°C was 1.36 times higher than at 15.0°C.
AB - A novel heterotrophic-autotrophic denitrification (HAD) approach supported by mixing granulated spongy iron, methanol, and mixed bacteria was proposed for the remediation of nitrate-nitrogen (NO 3-N) contaminated groundwater in a dissolved oxygen (DO)-rich environment. The HAD process involves biological deoxygenation, chemical reduction (CR) of NO 3-N and DO, heterotrophic denitrification (HD), and autotrophic denitrification (AD). Batch experiments were performed to: (1) investigate deoxygenation capacities of HAD; (2) determine the contributions of AD, HD, and CR to the overall NO 3-N removal in the HAD; and (3) evaluate the effects of environmental parameters on the HAD. There were 174, 205, and 2,437 min needed to completely reduce DO by the HAD, spongy iron-based CR, and by the mixed bacteria, respectively. The HAD depended on abiotic and biotic effects to remove DO. CR played a dominant role in deoxygenation in the HAD. After 5 days, approximately 100, 63.0, 20.1, and 9.7 % of the initial NO 3-N was removed in the HAD, HD, AD + CR, and CR incubations, respectively. CR, HD, and AD all contributed to the overall NO 3-N removal in the HAD. HD was the most important NO 3-N degradation mechanism in the HAD. There existed symbiotic, synergistic, and promotive effects of CR, HD, and AD within the HAD. The decrease in NO 3-N and the production of nitrite-nitrogen (NO 2-N) and ammonium-nitrogen (NH 4-N) in the HAD were closely related to the C to N weight ratio. The C to N ratio of 3.75:1 was optimal for complete denitrification. Denitrification rate at 27.5°C was 1.36 times higher than at 15.0°C.
KW - Groundwater
KW - Heterotrophic-autotrophic denitrification (HAD)
KW - Methanol
KW - Nitrate-nitrogen
KW - Spongy iron
UR - http://www.scopus.com/inward/record.url?scp=84865496525&partnerID=8YFLogxK
U2 - 10.1007/s11270-012-1170-0
DO - 10.1007/s11270-012-1170-0
M3 - Article
SN - 0049-6979
VL - 223
SP - 4029
EP - 4038
JO - Water Air and Soil Pollution
JF - Water Air and Soil Pollution
IS - 7
ER -
