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Corresponding Author

Elsheikh, Mahmoud

Subject Area

Civil and Environmental Engineering

Article Type

Original Study

Abstract

Disposing partially treated or untreated domestic and industrial wastewater into Egyptian drains violates their water quality standards and makes drains water unsuitable for reuse and pollute the receiving water body. A growing interest in effective low-cost treatment of polluted water and wastewater has brought many researches on constructed wetlands (CWs). Many CWs have been commissioned to treat various types of waters such as urban, agricultural runoff, municipal, industrial wastewaters, and acid mine drainage. This study evaluate a free water surface (FWS) CWs -(by far the largest application CWs in Egypt)- used to enhance water quality in Bahr El Baqar drain which located on the northeastern edge of the Egyptian Nile Delta, and discharge its water to Lake Manzala which has many fishing activities and connect to the Mediterranean Sea. The full capacity of the system is 25000 m3/d, the amount of water is divided to three parts; five FWS CWs beds of high flow rate "HFR" of 0.344 m3-/m3-d, five FWS CWs beds of low flow rate "LFR" of 0.048 m/m'-d and reciprocated cells of flow 500 m3ld. The concentrations of different contaminants along the CWs system were measured and analyzed for an assessment and modeling of treatment efficiency. The effluent was compared with the Egyptian regulation of water quality in agricultural drains (Law 4/1994). Due to the high percent of agriculture drains, the concentrations of contaminants in the influent were relatively low, thus the percentages of removal for the different contaminants were as follows: BODs (52%), COD (50%), TSS (87%), TDS (32%), NH4-N (66%), POs (52%), Fe (51%), Cu (36%), Zn (47%) and Pb (52%). The natural vegetation also increased the value of dissolved oxygen in the treated effluent considerably. There was little difference in the removal efficiencies between the HFR and LFR beds in the system.

Keywords

Polluted drain water; constructed wetlands; Free Water Surface; hydraulic loading rates; nutrient removals; trace metals

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