Designing Constructed Wetlands for Nitrogen Removal

Many constructed wetlands adequately treat BOD5, TSS, and bacteria. However, a review of nitrogen (N) data from 52 constructed and natural wetlands in the North American data base confirmed that N removal was variable. Nitrification and denitrification require aerobic and anaerobic conditions. This paper presents case histories of systems that use alternating shallow and deep water zones to create both environments. Regression analysis of N removal and N loadings in 18 shallow-deep water systems suggested that NH4+ loading (kg N/ha/day) could be used to predict effluent NH4+ values. Combinations of shallow water-emergent vegetation and deep water-submergent vegetation with low NH4+ (and TKN) loading rates can produce very low levels of discharged NH4+.

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The Use of Bacteriocin-Producing Pediococcus acidilactici to Control Postprocessing Listeria monocytogenes Contamination of Frankfurters1

Journal of Food Protection ◽

10.4315/0362-028x-54.9.681 ◽

1991 ◽

Vol 54 (9) ◽

pp. 681-686 ◽

Cited By ~ 71

Author(s):

ELAINE D. BERRY ◽

ROBERT W. HUTKINS ◽

ROGER W. MANDIGO

Keyword(s):

Listeria Monocytogenes ◽

No Reduction ◽

Initial Level ◽

Lag Time ◽

Storage Conditions ◽

Pediococcus Acidilactici ◽

Anaerobic Conditions ◽

Aerobic Conditions ◽

Low Levels ◽

Aerobic And Anaerobic

The ability of a bacteriocin-producing Pediococcus acidilactici to control postprocessing Listeria monocytogenes contamination of frankfurters was examined. Bacteriocin-producing P. acidilactici JD1–23 or its plasmid-cured derivative JD-M and a five-strain composite of L. monocytogenes were inoculated onto fully processed frankfurters. Under normal storage conditions at 4°C under vacuum, L. monocytogenes without added pediococci grew from an initial level of 104 CFU/g to a final level of 106 CFU/g over 60 d, with a lag time of 20–30 d. Under the same conditions, high levels (107 CFU/g) of either pediococcal strain inhibited growth of L. monocytogenes up to 60 d, although no reduction of cells occurred. With low levels of pediococci (103–104 CFU/g), Listeria grew, although the lag time was increased, and a bacteriocin effect was observed on frankfurters inoculated with JD1–23. In additional experiments done at 4°C and 15°C under aerobic and anaerobic conditions, levels of 107–108 CFU/g of either pediococci were observed to control Listeria growth on frankfurters at 15°C under anaerobic conditions for up to 15 d. At 4°C under aerobic conditions, L. monocytogenes grew on frankfurters inoculated with JD-M, while JD1–23 inhibited growth of the organism up to 30 d. At 15°C under aerobic conditions, L. monocytogenes grew in the presence of either pediococci, although a bacteriocin effect was indicated. Package atmosphere was observed to affect L. monocytogenes growth on this product.

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Late Quaternary palaeo-oceanography of the Denmark Strait overflow pathway, South-East Greenland margin

Geology of Greenland Survey Bulletin ◽

10.34194/ggu-bulletin.v180.6514 ◽

1998 ◽

Vol 180 ◽

pp. 163-167

Author(s):

Antoon Kuijpers ◽

Jørn Bo Jensen ◽

Simon R . Troelstra ◽

And shipboard scientific party of RV Professor Logachev and RV Dana

Keyword(s):

North Atlantic ◽

Deep Water ◽

Deep Convection ◽

Conveyor Belt ◽

Water Masses ◽

Labrador Sea ◽

Greenland Sea ◽

The North ◽

Denmark Strait ◽

The North Atlantic

Direct interaction between the atmosphere and the deep ocean basins takes place today only in the Southern Ocean near the Antarctic continent and in the northern extremity of the North Atlantic Ocean, notably in the Norwegian–Greenland Sea and Labrador Sea. Cooling and evaporation cause surface waters in the latter region to become dense and sink. At depth, further mixing occurs with Arctic water masses from adjacent polar shelves. Export of these water masses from the Norwegian–Greenland Sea (Norwegian Sea Overflow Water) to the North Atlantic basin occurs via two major gateways, the Denmark Strait system and the Faeroe– Shetland Channel and Faeroe Bank Channel system (e.g. Dickson et al. 1990; Fig.1). Deep convection in the Labrador Sea produces intermediate waters (Labrador Sea Water), which spreads across the North Atlantic. Deep waters thus formed in the North Atlantic (North Atlantic Deep Water) constitute an essential component of a global ‘conveyor’ belt extending from the North Atlantic via the Southern and Indian Oceans to the Pacific. Water masses return as a (warm) surface water flow. In the North Atlantic this is the Gulf Stream and the relatively warm and saline North Atlantic Current. Numerous palaeo-oceanographic studies have indicated that climatic changes in the North Atlantic region are closely related to changes in surface circulation and in the production of North Atlantic Deep Water. Abrupt shut-down of the ocean-overturning and subsequently of the conveyor belt is believed to represent a potential explanation for rapid climate deterioration at high latitudes, such as those that caused the Quaternary ice ages. Here it should be noted, that significant changes in deep convection in Greenland waters have also recently occurred. While in the Greenland Sea deep water formation over the last decade has drastically decreased, a strong increase of deep convection has simultaneously been observed in the Labrador Sea (Sy et al. 1997).

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Effect of Aerobic and Anaerobic Conditions on Chlorophenol Sorption in Wetland Soils

Soil Science Society of America Journal ◽

10.2136/sssaj2003.0787 ◽

2003 ◽

Vol 67 (3) ◽

pp. 787 ◽

Cited By ~ 13

Author(s):

Elisa D'Angelo ◽

K. R. Reddy

Keyword(s):

Wetland Soils ◽

Anaerobic Conditions ◽

Aerobic And Anaerobic ◽

Aerobic And Anaerobic Conditions

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Novel biological removal of hazardous chemicals at trace levels

Water Science & Technology ◽

10.2166/wst.2000.0238 ◽

2000 ◽

Vol 42 (12) ◽

pp. 49-60 ◽

Cited By ~ 4

Author(s):

P.L. McCarty

Keyword(s):

Plug Flow ◽

Chlorinated Solvents ◽

Biological Removal ◽

Sanitary Landfills ◽

Low Levels ◽

Trace Chemicals ◽

Engineered Systems ◽

Biological Methods ◽

Aerobic And Anaerobic ◽

Flow Treatment

Of recent concern is the removal of toxic compounds in wastewaters, soils, and groundwater to concentrations in the low microgram per litre level or less. Threshold limits to bioremediation exist and must be considered in biological treatment schemes to achieve such limits. These limits may be related to reaction kinetics or thermodynamics. Techniques for removing compounds below threshold levels exist that rely on appropriate approaches such as plug flow treatment. Novel biological methods exist for removal of refractory contaminants to low levels. Examples are provided for removal of trace levels of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), that employ dehalorespiration under anaerobic conditions or cometabolism under aerobic conditions. These approaches are currently being used in engineered systems or through natural attenuation for remediation of soils and groundwater. Successful results offer insights for similar removals of trace chemicals in both aerobic and anaerobic biological systems for treatment of wastewaters and sanitary landfills.

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Plant diversity increases N removal in constructed wetlands when multiple rather than single N processes are considered

Ecological Applications ◽

10.1002/eap.1965 ◽

2019 ◽

Vol 29 (7) ◽

Cited By ~ 4

Author(s):

Yan Geng ◽

Ying Ge ◽

Bin Luo ◽

Zhengxin Chen ◽

Yong Min ◽

...

Keyword(s):

Constructed Wetlands ◽

Plant Diversity ◽

N Removal

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Analysis of Characteristics and Driving Factors of Wetland Landscape Pattern Change in Henan Province from 1980 to 2015

Land ◽

10.3390/land10060564 ◽

2021 ◽

Vol 10 (6) ◽

pp. 564

Author(s):

Heying Li ◽

Jiayao Wang ◽

Jianchen Zhang ◽

Fen Qin ◽

Jiyuan Hu ◽

...

Keyword(s):

Correlation Analysis ◽

Constructed Wetlands ◽

Redundancy Analysis ◽

Yellow River ◽

Land Development ◽

Henan Province ◽

Driving Factors ◽

Wetland Area ◽

Natural Wetlands ◽

Temporal And Spatial

The study of the temporal and spatial evolution of wetland landscapes and its driving factors is an important reference for wetland ecological restoration and protection. This article utilized seven periods of land use data in Henan Province from 1980 to 2015 to extract the spatial distribution characteristics of wetlands and analyze the temporal and spatial changes of wetlands in Henan Province. Transfer matrix, landscape metrics, correlation analysis, and redundancy analysis were applied to calculate and analyze the transformation types and area of wetland resources between all consecutive periods, and then the main driving factors of wetland expansion/contraction were explored. First, the total wetland area in Henan Province increased by 28% from 1980 to 2015, and the increased wetland area was mainly constructed wetlands, including paddy field, reservoir and pond, and canal. Natural wetlands such as marsh, lake, and floodplain decreased by 74%. Marsh area declined the most during 1990–1995, and was mainly transformed into floodplain and “Others” because of agricultural reclamation, low precipitation, and low Yellow River runoff. The floodplain area dropped the most from 2005 to 2010, mainly converted to canals and “Others” because of reclamation, exploitation of groundwater, the construction of the South–to–North Water Transfer Project, and recreational land development. Second, the results of correlation analysis and redundancy analysis indicated that economic factors were positively correlated with the area of some constructed wetlands and negatively correlated with the area of some natural wetlands. Socioeconomic development was the main driving factors for changes in wetland types. The proportion of wetland habitat in Henan Province in 2015 was only 0.3%, which is low compared to the Chinese average of 2.7%. The government should pay more attention to the restoration of natural wetlands in Henan Province.

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