scholarly journals Nitrogen removal from landfill leachate in constructed wetlands with reed and willow: Redox potential in the root zone

2012 ◽  
Vol 97 ◽  
pp. 22-27 ◽  
Author(s):  
Andrzej Białowiec ◽  
Laura Davies ◽  
Antonio Albuquerque ◽  
Peter F. Randerson
Keyword(s):  
Redox Potential ◽  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Landfill Leachate ◽  
Root Zone

scholarly journals Willows and Reeds for Biomediation of Landfill Leachate: Redox Potential in the Root Zone

2017 ◽  
pp. 877-886
Author(s):  
Peter Randerson ◽  
Laura Davies ◽  
Antonio Albuquerque ◽  
Andrzej Białowiec
Keyword(s):  
Redox Potential ◽  
Constructed Wetlands ◽  
Root Exudates ◽  
Landfill Leachate ◽  
Root Zone ◽  
Oxygen Demand ◽  
Pollutant Removal ◽  
Nitrogen Loads ◽  
Low Levels ◽  
Control Tank

Constructed wetlands can be used for bioremediation of landfill leachate (LL) making it safe to discharge into the environment. Wetland plants (reed and willow), contribute to pollutant removal, particularly of organic and nitrogen loads. Root exudates stimulate microbial activity and elevate oxygen levels in the rhizosphere which promotes nitrification. This study investigated the effects of reed and willow on bioremediation of LL in comparison with an unplanted control by measuring redox potential levels in the rhizosphere of microcosm systems in a greenhouse. Redox potential in the reed rhizosphere was consistently the highest, with the willow rhizosphere consistently the lowest. Redox potential fluctuated in the willow rhizosphere during daylight hours, with large decreases in the morning. Levels of NH4 + decreased dramatically in the first day of the experiment and remained at similar low levels in all tanks. Removal of ammonia took place in the control tank with peaks in NO2 - and NO3 -, but levels of NO3 - remained high. Removal of ammonia was also observed in the reed tank with a peak in NO2 -, but there was no peak in NO3 -, as well as in the willow tank, but there were no peaks in NO2 - or NO3 -. Final levels of totalnitrogen, nitrate and chemical oxygen demand where considerably lower in the reed and willow tank than the unplanted control.

Enhancement of nitrogen removal in subsurface flow constructed wetlands employing a 2-stage configuration, an unsaturated zone, and recirculation

1995 ◽  
Vol 32 (3) ◽  
pp. 59-67 ◽  
Author(s):  
Kevin D. White
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Subsurface Flow ◽  
Great Promise ◽  
Effluent Recirculation ◽  
Wetland Treatment ◽  
Subsurface Flow Constructed Wetlands ◽  
Inlet Zone ◽  
Bod Removal

Constructed wetland technology is currently evolving into an acceptable, economically competitive alternative for many wastewater treatment applications. Although showing great promise for removing carbonaceous materials from wastewater, wetland systems have not been as successful at nitrification. This is primarily due to oxygen limitations. Nitrification does occur in conventional wetland treatment systems, but typically requires long hydraulic retention times. This paper describes a study that first evaluated the capability of subsurface flow constructed wetlands to treat a high strength seafood processor wastewater and then evaluated passive aeration configurations and effluent recirculation with respect to nitrogen treatment efficiency. The first stage of a 2-stage wetland treatment system exhibited a relatively short hydraulic retention time and was designed for BOD removal only. The second stage wetland employed an unsaturated inlet zone and effluent recirculation to enhance nitrification. Results indicate that organic loading, and thus BOD removal, in the first stage wetland is key to optimal nitrification. Passive aeration through an unsaturated inlet zone and recirculation achieved up to 65-70 per cent ammonia nitrogen removal at hydraulic retention times of about 3.5 days. Inlet zone configuration and effluent recirculation is shown to enhance the nitrogen removal capability of constructed wetland treatment systems.

scholarly journals The Use of Constructed Wetlands for Nitrogen Removal from Agricultural Drainage: a Review

2017 ◽  
Vol 48 (2) ◽  
pp. 82-91 ◽  
Author(s):  
Jan Vymazal
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Coastal Waters ◽  
Free Water ◽  
Literature Survey ◽  
Agricultural Drainage ◽  
Severe Problem ◽  
Nitrogen Loads ◽  
Predominant Form ◽  
Close Relationship

Abstract Diffuse pollution from agricultural drainage is a severe problem for water quality and it is a major reason for eutrophication of both freshwaters and coastal waters. Constructed wetlands were proposed as a suitable tool for removal of nitrogen from agricultural drainage in the early 1990s. Since then constructed wetlands with free water surface have been successfully used in Europe, North America, Asia, and Australia. The predominant form of nitrogen in agricultural drainage waters is nitrate and therefore denitrification is considered as the major removal process. The literature survey of 41 full-scale constructed wetlands revealed that removed nitrogen amount varied widely between 11 and 13 026 kg N ha-1 per year with the median removal of 426 kg N ha-1 per year. A very close relationship was found between inflow and removed nitrogen loads but the overall percentual efficiency decreases with increasing inflow nitrogen load. It has also been found that nitrogen removal depends on the size of constructed wetland (W) as compared to catchment (C) area. The survey indicated that the W/C greater than 1% does not result in any substantial increase of nitrogen removal. There are still some gaps in our knowledge that need to be evaluated, namely the optimum vegetation maintenance.

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