Performance Evaluation of Horizontal Subsurface Flow–Constructed Wetlands for the Treatment of Domestic Wastewater in the Tropics

• Published in: Journal of environmental engineering (New York, N.Y.) Vol. 139; no. 3; pp. 358 - 367
• Main Authors: Mburu, Njenga, Tebitendwa, Sylvie M, Rousseau, Diederik P. L, van Bruggen, J. J. A, Lens, Piet N. L
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01.03.2013
• Subjects: Applied sciences; Biological and physicochemical phenomena; Discharge; Efficiency; Effluents; Exact sciences and technology; General purification processes; General treatment and storage processes; Gravel; Natural water pollution; Pilots; Pollution; Technical Papers; Tropics; Wastes; Wastewater treatment; Wastewaters; Water treatment and pollution; Wetlands; Kenya; Background concentration; Organic matter; Waste treatment; Tropical zone; Developing countries; Phosphorus; Sulfur dioxide; Biological purification; Wetlands; Domestic waste water; Tropical regions; Chemical oxygen demand; Artificial medium; First order; Water pollution; Subsurface flow; Kinetics; Rate constant; Waste water purification; Wetland
• ISSN: 0733-9372; 1943-7870
• DOI: 10.1061/(ASCE)EE.1943-7870.0000636

AbstractThe lack of information on constructed-wetland performance in the tropics is among the factors that have hindered the adoption of low-cost wastewater-treatment technologies as alternatives to conventional wastewater treatment. A pilot scale study was undertaken in Juja (Kenya) to assess the performance of horizontal subsurface flow–constructed wetlands (HSSF-CWs) under tropical conditions. Primary domestic wastewater effluent was continuously fed into three replicate wetland cells, each with an area of 22.5  m2 (7.5×3  m) and with gravel as substrate. The study revealed successful performance of the wetlands in terms of compliance with local discharge standards with respect to chemical-oxygen demand (COD), BOD5, total suspended solids (TSS), and SO42−-S at an average mass removal efficiency between 58.9 and 74.9%. Moderate removal of NH4+-N and total phosphorus (TP) was recorded. The estimated first-order aerial-rate constant and the BOD5 background concentration showed the HSSF-CW to be area-requirement competitive. The good performance in organic matter and suspended solids removal reveals that HSSF-CW can help to alleviate the current environmental pollution problems experienced in developing countries caused by the discharge of partially treated or untreated domestic wastewater.