Remediation of nitrate-nitrogen contaminated groundwater using a pilot-scale two-layer heterotrophic-autotrophic denitrification permeable reactive barrier with spongy iron/pine bark.
A novel two-layer heterotrophic-autotrophic denitrification (HAD) permeable reactive barrier (PRB) was proposed for remediating nitrate-nitrogen contaminated groundwater in an oxygen rich environment, which has a packing structure of an upstream pine bark layer and a downstream spongy iron and river sand mixture layer. The HAD PRB involves biological deoxygenation, heterotrophic denitrification, hydrogenotrophic denitrification, and anaerobic Fe corrosion. Column and batch experiments were performed to: (1) investigate the NO3(-)-N removal and inorganic geochemistry; (2) explore the nitrogen transformation and removal mechanisms; (3) identify the hydrogenotrophic denitrification capacity; and (4) evaluate the HAD performance by comparison with other approaches. The results showed that the HAD PRB could maintain constant high NO3(-)-N removal efficiency (>91%) before 38 pore volumes (PVs) of operation (corresponding to 504d), form little or even negative NO2(-)-N during the 45 PVs, and produce low NH4(+)-N after 10 PVs. Aerobic heterotrophic bacteria played a dominant role in oxygen depletion via aerobic respiration, providing more CO2 for hydrogenotrophic denitrification. The HAD PRB significantly relied on heterotrophic denitrification. Hydrogenotrophic denitrification removed 10-20% of the initial NO3(-)-N. Effluent total organic carbon decreased from 403.44mgL(-1) at PV 1 to 9.34mgL(-1) at PV 45. Packing structure had a noticeable effect on its denitrification.
China Meat Research Center, Beijing Academy of Food Sciences, Beijing 100068, China; Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China.
Guoxin
G
Huang
National Research Center for Geoanalysis, Beijing 100037, China. Electronic address: huangy1978@126.com.
Yuanying
Y
Huang
Hydrogeology and Engineering Geology Prospecting Institute of Heilongjiang Province, Harbin 150030, China.
Hongyan
H
Hu
Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China.
Fei
F
Liu
Yunnan HITECH Environmental Protection Technology Co., Ltd., Kunming 650032, China.
Ying
Y
Zhang
China Meat Research Center, Beijing Academy of Food Sciences, Beijing 100068, China.
Renwei
R
Deng
D000818:Animals; D052818:Autotrophic Processes; D001673:Biodegradation, Environmental; D002244:Carbon / Q000032:analysis; D058440:Denitrification; D004867:Equipment Design; D060587:Groundwater / Q000737:chemistry*; D052836:Heterotrophic Processes; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010100:Oxygen / Q000032:analysis / Q000737:chemistry; D010539:Permeability; D028223:Pinus; D024301:Plant Bark; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
D009566:Nitrates; D014874:Water Pollutants, Chemical; D002244:Carbon; D007501:Iron; D009584:Nitrogen; D010100:Oxygen
Groundwater remediation; Heterotrophic–autotrophic denitrification (HAD); Nitrate–nitrogen; Permeable reactive barrier (PRB); Pine bark; Spongy iron