Removal of high NO₃-concentrations in saline water through autotrophic denitrification by the bacterium Thiobacillus denitrificans strain MP

TY - JOUR

T1 - Removal of high NO3-concentrations in saline water through autotrophic denitrification by the bacterium Thiobacillus denitrificans strain MP

AU - Gu, J. D.

AU - Qiu, W.

AU - Koenig, Albert

AU - Fan, Y.

PY - 2004

Y1 - 2004

N2 - Autotrophic denitrification by Thiobacillus denitrificans MP isolated from mangrove was investigated in both a sulphur-limestone column reactor and a fermenter. More than 97.5% of the nitrate (NO3-) in the 250 mg NO3 --N/L strong influent was removed after 14.3 hours in the column reactor. Influent NO3- was completely depleted in the lower part of the column as the hydraulic retention time increased and a slight pH drop was also observed along the reactor column due to the exhaustion of the buffering ability of the limestone. Trace amounts of oxygen present in the lower part of the reactor column resulted in the accumulation of nitrite and subsequent inhibition of further denitrification. The species composition of the bacterial community in the higher parts of the reactor column was morphologically more diverse than in the lower part. Denitrification by T. denitrificans MP reached an optimal level when the dissolved oxygen was maintained between 1.5-2% of saturation level in the automated fermenter. The stoichiometric ratios of ΔSO42- produced/ΔNO3--N removed were 6.81 and 9.32 in the reactor column and fermenter, respectively. This study suggests that efficient removal of high NO3- concentrations in water or wastewater can be achieved using autotrophic bacteria immobilized on surfaces of sulphur granules in the column system.

AB - Autotrophic denitrification by Thiobacillus denitrificans MP isolated from mangrove was investigated in both a sulphur-limestone column reactor and a fermenter. More than 97.5% of the nitrate (NO3-) in the 250 mg NO3 --N/L strong influent was removed after 14.3 hours in the column reactor. Influent NO3- was completely depleted in the lower part of the column as the hydraulic retention time increased and a slight pH drop was also observed along the reactor column due to the exhaustion of the buffering ability of the limestone. Trace amounts of oxygen present in the lower part of the reactor column resulted in the accumulation of nitrite and subsequent inhibition of further denitrification. The species composition of the bacterial community in the higher parts of the reactor column was morphologically more diverse than in the lower part. Denitrification by T. denitrificans MP reached an optimal level when the dissolved oxygen was maintained between 1.5-2% of saturation level in the automated fermenter. The stoichiometric ratios of ΔSO42- produced/ΔNO3--N removed were 6.81 and 9.32 in the reactor column and fermenter, respectively. This study suggests that efficient removal of high NO3- concentrations in water or wastewater can be achieved using autotrophic bacteria immobilized on surfaces of sulphur granules in the column system.

KW - Autotrophic denitrification

KW - Dissolved oxygen

KW - Inhibition

KW - Retention time

KW - Stoichiometry

KW - Thiobacillus denitrifications MP

UR - http://www.scopus.com/inward/record.url?scp=2442547215&partnerID=8YFLogxK

U2 - 10.2166/wst.2004.0743

DO - 10.2166/wst.2004.0743

M3 - 文章

C2 - 15137413

AN - SCOPUS:2442547215

SN - 0273-1223

VL - 49

SP - 105

EP - 112

JO - Water Science and Technology

JF - Water Science and Technology

IS - 5-6

ER -