Hydrology Research Vol 43 No 4 pp 476–488 © IWA Publishing 2012 doi:10.2166/nh.2012.133

Hydraulic performance of small free water surface constructed wetlands treating sugar factory effluent in western Kenya

Hristina Bodin and Jesper Persson

This study investigated, using a lithium salt tracer, how macrophyte species and hydraulic loading rate (HLR) of wastewater influenced hydraulics in constructed wetlands (CWs). Four pilot-scale CWs received 45 mm day⁻¹ of pre-treated sugar factory effluent and another four received 110 mm day⁻¹. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Results showed a significant negative connection between tracer mass recovery and wetland water leakages. Also, a significant negative relationship between active wetland water volume and macrophyte density was detected. Further, a significant effect of HLR on mass removal rates of NH₄⁺-N was observed. However, no significant effect of either HLR or macrophyte species on wetland hydraulic parameters was found.

Keywords: constructed wetland; Cyperus papyrus; Echinochloa pyramidalis; hydraulic loading rate; hydraulic tracer study; vegetation

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