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Li S.,Water Resources University | Huang G.,Beijing Academy of Food science | Kong X.,Chinese Academy of Geological Sciences | Yang Y.,Water Resources University | And 3 more authors.
Water Science and Technology

In situ remediation of ammonium-contaminated groundwater is possible through a zeolite permeable reactive barrier (PRB); however, zeolite's finite sorption capacity limits the long-term field application of PRBs. In this paper, a pilot-scale PRB was designed to achieve sustainable use of zeolite in removing ammonium (NH4+-N) through sequential nitrification, adsorption, and denitrification. An oxygen-releasing compound was added to ensure aerobic conditions in the upper layers of the PRB where NH4+-N was microbially oxidized to nitrate. Any remaining NH4+-N was removed abiotically in the zeolite layer. Under lower redox conditions, nitrate formed during nitrification was removed by denitrifying bacteria colonizing the zeolite. During the long-term operation (328 days), more than 90% of NH4+-N was consistently removed, and approximately 40% of the influent NH4+-N was oxidized to nitrate. As much as 60% of the nitrate formed in the PRB was reduced in the zeolite layer after 300 days of operation. Removal of NH4+-N from groundwater using a zeolite PRB through bacterial nitrification and abiotic adsorption is a promising approach. The zeolite PRB has the advantage of achieving sustainable use of zeolite and immediate NH4+-N removal. © IWA Publishing 2014. Source

Li S.,Water Resources University | Li M.,Water Resources University | Luo X.,Water Resources University | Huang G.,Beijing Academy of Food science | And 2 more authors.
Environmental Science and Pollution Research

Benzoic acid can affect the iron-oxide mineral dissolution and react with hydroxyl radical. This study investigated its effect on 1,2-dichloroethane removal process by siderite-catalyzed hydrogen peroxide and persulfate. The variation of benzoic acid concentrations can affect pH value and soluble iron concentrations; when benzoic acid varied from 0 to 0.5 mmol/L, pH increased while Fe2+ and Fe3+ concentrations decreased, resulting in 1,2-dichloroethane removal efficiency which decreased from 91.2 to 5.0 %. However, when benzoic acid varied from 0.5 to 10 mmol/L, pH decreased while Fe2+ and Fe3+ concentrations increased, resulting in 1,2-dichloroethane removal efficiency which increased from 5.0 to 83.4 %. © 2015, Springer-Verlag Berlin Heidelberg. Source

Huang G.,Water Resources University | Huang G.,Beijing Academy of Food science | Fallowfield H.,Flinders University | Guan H.,Flinders University | Liu F.,Water Resources University
Water, Air, and Soil Pollution

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. © 2012 Springer Science+Business Media B.V. Source

Huang G.,Water Resources University | Huang G.,Beijing Academy of Food science | Liu F.,Water Resources University | Yang Y.,Hydro Engineering Team of Sichuan Metallurgical Geology and Exploration Bureau | And 4 more authors.
Journal of Environmental Management

A novel fully passive permeable reactive barrier (PRB) with oxygen-releasing compound (ORC) and clinoptilolite was proposed for the removal of ammonium-nitrogen from groundwater. The PRB involves a combination of oxygen release, biological nitrification, ion exchange, and bioregeneration. A pilot-scale performance comparison experiment was carried out employing three parallel columns to assess the proposed PRB. The results showed that the PRB achieved nearly complete NH4 +-N depletion (>99%). NH4 +-N of 5.23-10.88mg/L was removed, and NO2 --N of <1.93mg/L and NO3 --N of 2.03-19.67mg/L were generated. Ion exchange and biological nitrification both contributed to NH4 +-N removal, and the latter played a dominant role under the condition of sufficient oxygen. Biological nitrification favored a delay in sorption saturation and a release of exchange sites. The ORC could sufficiently, efficiently supply oxygen for approximately 120 pore volumes. The clinoptilolite ensured a robust NH4 +-N removal in case of temporary insufficient biological activities. No external alkalinity sources had to be supplied and no inhibition of aerobic metabolism occurred. The ceramicite had a negligible effect on the biomass growth. Based on the research findings, a full-scale continuous wall PRB was installed in Shenyang, China in 2012. © 2015 Elsevier Ltd. Source

Kong X.,Chinese Academy of Geological Sciences | Bi E.,Water Resources University | Liu F.,Water Resources University | Huang G.,Beijing Academy of Food science | Ma J.,Chinese Academy of Geological Sciences
Environmental Technology (United Kingdom)

In order to remediate ammonium contaminated groundwater, an innovative multimedia permeable reactive barrier (M-PRB) was proposed, which consisted of sequential columns combining oxygen releasing compound (ORC), zeolite, spongy iron and pine bark in the laboratory scale. Results showed that both ammonium and nitrate could be reduced to levels below the regulatory discharge limits through ion exchange and microbial degradation (nitrification and denitrification) in different compartments of the M-PRB system. The concentration of dissolved oxygen (DO) increased from 2 to above 20mg/L after the simulated groundwater flowed through the oxygen releasing column packed with ORC, demonstrating that ORC could supply sufficient oxygen for subsequent microbial nitrification. Ammonium was efficiently removed from about 10 to below 0.5mgN/L in the aerobic reaction column which was filled with biological zeolite. After 54 operating days, more than 70% ammonium could be removed by microbial nitrification in the aerobic reaction column, indicating that the combined use of ion exchange and nitrication by biological zeolite could ensure high and sustainable ammonium removal efficiency. To avoid the second pollution of nitrate produced by the former nitrification, spongy iron and pine bark were used to remove oxygen and supply organic carbon for heterotrophic denitrification in the oxygen removal column and anaerobic reaction column separately. The concentration of nitrate decreased from 14 to below 5mgN/L through spongy iron-based chemical reduction and microbial denitrification. © 2014 Taylor & Francis. Source

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