Effect of carbon source on the denitrification in constructed wetlands

ESPC State Key Joint Laboratory, Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China.
Journal of Environmental Sciences (Impact Factor: 1.92). 01/2009; 21(8):1036-43. DOI: 10.1016/S1001-0742(08)62379-7
Source: PubMed

ABSTRACT The ability of constructed wetlands with different plants in nitrate removal were investigated. The factors promoting the rates of denitrification including organic carbon, nitrate load, plants in wetlands, pH and water temperature in field were systematically investigated. The results showed that the additional carbon source (glucose) can remarkably improve the nitrate removal ability of the constructed wetland. It demonstrated that the nitrate removal rate can increase from 20% to more than 50% in summer and from 10% to 30% in winter, when the nitrate concentration was 30-40 mg/L, the retention time was 24 h and 25 mg/L dissolved organic carbon (DOC) was ploughed into the constructed wetland. However, the nitrite in the constructed wetland accumulated a little with the supply of the additional carbon source in summer and winter, and it increased from 0.15 to 2 mg/L in the effluent. It was also found that the abilities of plant in adjusting pH and temperature can result in an increase of denitrification in wetlands. The seasonal change may also impact the denitrification.

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Article: Effect of carbon source on the denitrification in constructed wetlands

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    • "Thus, organic matter may supply dissolved organic carbon (DOC) to microbes. Lu et al. (2009) report that an additional carbon source (glucose) can remarkably improve the nitrate removal ability of a constructed wetland. They demonstrate that the nitrate removal rate can increase from 20% to more than 50% in summer Table 5 Comparison of denitrification rates in various created and natural wetlands. "
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    Ecological Engineering 08/2014; 71:628–638. DOI:10.1016/j.ecoleng.2014.07.064 · 3.04 Impact Factor
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    • "condary treated nitri - fied effluents from conventional wastewater treatment systems that virtually contain no organic matter ( Headley et al . , 2001 ) . In conventional wastewater treatment systems , this limitation can be overcome by the addition of an external dissolved organic carbon source , such as methanol , ethanol , acetate or glucose ( Lu et al . , 2009 ) . However , the plants growing in wetlands automat - ically convert atmospheric CO 2 into biomass ( organic C ) through photosynthesis . This endogenously derived organic C in the wet - lands can then potentially become available to denitrifying bacteria through a number of pathways , including death and decomposition of plant litter "
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    ABSTRACT: Rooted emergent wetland plants may deliver organic carbon via root exudates to fuel the microbial denitrification process in subsurface flow constructed wetland systems receiving nitrate-rich and low-carbon wastewater. We quantified the amount of dissolved organic carbon (DOC) released from roots of three wetland species, Phragmites australis, Iris pseudacorus and Juncus effusus, which are commonly used in constructed wetlands. Plants were grown hydroponically at two temperatures (10 and 20 °C) and three light-regimes (a normal 14 h:10 h light:dark cycle, continuous light and continuous dark), and the release rates of DOC from the roots as well as the uptake rates of NH4-N, NO3-N, PO4-P and K were analyzed. DOC release rates were significantly different among the three species, and were also affected by temperature and light-regime. At 20 °C, higher amounts of DOC were generally released in the root exudates than at 10 °C. The average DOC release rate of the three species was nearly two times higher in the light (10.2 ± 0.7 μg g−1 root DM h−1) than in the dark (6.8 ± 0.7 μg g−1 root DM h−1). As expected, DOC release rates were positively related to the relative growth rate (RGR) and nutrient uptake rate. DOC release rates amounted to 0.6–4.8% of the net photosynthetically fixed carbon. Extrapolating the laboratory measurements to field conditions suggests that plant root exudates may potentially fuel a denitrification rate of 94–267 kg N ha−1 year−1 in subsurface flow constructed wetlands. Hence, root exudates are potentially important as an organic C source for denitrification in lightly loaded subsurface flow constructed wetland systems receiving nitrate-rich water with a low content of BOD (e.g. nitrified effluent or agricultural drainage).
    Ecological Engineering 12/2013; 61:555–563. DOI:10.1016/j.ecoleng.2013.02.014 · 3.04 Impact Factor
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    • "Biological nitrogen removal in conventional wetlands is often restricted by lack of organic carbon source. External carbon addition was then adopted to enhance the influent water COD/N ratios in some studies to support denitrification (Ingersoll and Baker, 1998; Lu et al., 2009). Zhao et al. (2010) found that conventional VFCWs obtained total nitrogen (TN) removal efficiency of 25–62% when COD/N ratios changed from 2.5 to 10 and highest TN removal rates were observed at COD/N ratio of 2.5–5. "
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    Bioresource Technology 03/2013; 141. DOI:10.1016/j.biortech.2013.03.077 · 5.04 Impact Factor
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