Friday, 10 February 2017

Improvement of nitrogen removal by external aeration and intermittent circulation in a subsurface flow constructed wetland of landscape garden ponds


Highlights

  • Nitrogen removal performance was improved by aeration and intermittent circulation.
  • Math Eq removal rate improved by 57% over SSF CW without aeration and circulation.
  • External aeration and intermittent circulation improved O2 transportation in SSF CW.

Abstract

An external aeration and intermittent circulation were used to improve the nitrogen removal performance of subsurface flow constructed wetland (SSF CW) in landscape garden ponds. Nitrification was the main mechanism of ammonium–nitrogen (Math Eq) removal and partial nitrification/anaerobic ammonia oxidation was a minor process. Field measurements yielded a removal rate of Math Eq of 0.266–0.566 g N/d m2 and a corresponding temperature-dependent rate constant of 0.184 d−1 to 0.377 d−1 representing an improvement over nitrogen removal. The nitrate–nitrogen (Math Eq) removal was degraded to the background level of Math Eq concentration in an environment with a high concentration of dissolved oxygen. The Math Eq removal rate ranged from 0.0393 g N/d m2 to 0.0825 g N/d m2 and resulted from aerobic denitrification, indicating that external aeration and intermittent circulation effectively improved oxygen transportation in SSF CW. This could remove Math Eq of the effluent of SSF CW when using in-tank aeration to improve the nitrogen removal performance of SSF CW.

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