Performance evaluation of sedimentation followed by constructed wetlands for drainage water treatment

Mahmoud Nasr, Sayed Ismail

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Performance of a constructed wetland utilized to improve the water quality in “Bahr El-Baqar” drain was evaluated. The drain is located on the north-eastern edge of the Nile Delta, which receives a mixture of domestic and agricultural discharges. The treatment system consists of two sedimentation units followed by ten constructed wetlands operated as free water surface flow basins. The drain discharges its water into “El-Manzala” Lake, which has fishing activities and connects to the Mediterranean Sea. Results showed that, at an organic loading of 2,800 kg BOD (biological oxygen demand) d-1, treatment facilities achieved overall removals: 75 ± 3% (BOD), 57 ± 5% (chemical oxygen demand, COD), 78 ± 2% (suspended solids), 50 ± 5% (NH4) and 44 ± 8% (total P). Profiles of basins revealed that, due to natural aeration at the water surface (shallowness) and from the roots of the plants, dissolved oxygen (DO) levels gradually increased from 1.0 ± 0.1 to 6.5 ± 0.7 mg L-1. At a hydraulic retention time (HRT) of 60 h, the wetlands were able to reach the allowable limits in the Law 48/1982 for DO (> 4 mg L-1), BOD (< 40 mg L-1) and COD (< 80 mg L-1) after 60% of their longitudinal length. Ordinary differential equations were implemented to model the biological process occurring in the wetlands. It was observed that the simulated results tracked the measured data well, and the stoichiometric parameters were: YH = 0.45 mg VSS mg-1 BOD, YA = 0.26 mg COD mg-1 N, and YN = 0.06 mg N mg-1 COD. The model predicted that operating the basins at HRT of 73 h, removal of NH4 will be enhanced by 24%. At this condition, the effluent NH4 is allowable for adequate discharge according to Law 48/1982 (NH4-N < 3.0 mg L-1).

Original languageEnglish
Pages (from-to)141-150
Number of pages10
JournalSustainable Environment Research
Volume25
Issue number3
Publication statusPublished - 1 Jan 2015
Externally publishedYes

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Keywords

  • Constructed wetlands
  • Modeling
  • Nutrient transformation
  • Polluted drain water
  • Removal efficiency

ASJC Scopus subject areas

  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

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