© IWA Publishing 2011 Water Practice & Technology Vol 6 No 3 doi:10.2166/wpt.2011.047 Use of engineered wetlands for onsite treatment of wastewater by the local communities: Experiences from Tanzania K. N. Njau*, W. J. S. Mwegoha** , ***, R. J. Kimwaga* and J. H. Y. Katima* *College of Engineering and Technology, University of Dar es Salaam, P.O.Box 35131, Dar es Salaam, Tanzania **School of Environmental Science and Technology, Ardhi University, P. O. Box 35176, Dar es Salaam, Tanzania ***Corresponding Author [Tel: (255) 786 316055, e-mail: Mwegoha@hotmail.com Fax (255) 22 2775391] Since its inception about 10 years ago, Constructed Wetlands (CWs) technology has been well received in Tanzania due to a wide range of functions. CWs are used to treat wastewater from municipal systems, pulp and paper industries, prisons, schools and colleges. Among the recipients of CWs are the Moshi Urban Water and Sewerage Authority (MUWSA) for polishing Waste Stabilization Ponds effluents, Kibo Paper Mills for treating industrial effluents, Shinyanga, Malya and Bariadi Prison and Kleruu Teachers College and Ruaha High School for Treatment of domestic wastewater. All these systems are Horizontal Sub-Surface Flow Constructed Wetlands. This paper reports on results of a survey of the six (6) mentioned operating CW systems, focusing on the existing situation and the observed operation and maintenance challenges and needs. The survey was carried by visiting the CWs and sampling for determination of BOD5, COD, PO4 2- , NO3-N, and NH3-N. Results from the survey and laboratory analyses in three of these CWs indicated lack of general and site-specific operation and maintenance guidelines, which seriously affect life of these systems, aesthetics and performance of pollutant removal. This is evidenced by failure of these systems to meet local and international permissible discharge limits to the receiving water bodies. Keywords: constructed wetland, maintenance, operation, performance, wastewater Constructed Wetlands (CW) must be managed if they are to perform well (Beharell, 2004). Thus, CW require regular monitoring and maintenance to ensure it remains functional and in a 'healthy' condition. Development of Operation and Maintenance (O&M) guidelines should be consistent with the purposes and intended life of the wetland, which includes the requirements for safety, water management, cleanout of sediment, maintenance of structures, embankments, and vegetation, control measures for vectors and pests, and containment of potential pollutants during maintenance operations (Kuginis, 1998; Beharell et al., 1998; Beharell, 2004). In Tanzania, CW technology dates back to 1998 when the first research group was launched at the University of Dar es Salaam under DANIDA funding. The group conducted research on the feasibility of using Horizontal Sub-surface Flow Constructed Wetlands in Tanzania. 10 years of successful studies and awareness raising about what these systems can do in terms of pollution control resulted into massive acceptance by the local public. A number of projects on the use of CW systems for wastewater treatment were developed notably in Iringa, Moshi, Shinyanga, Dar es Salaam and Mwanza. However, the major challenge facing these systems is lack of guidelines on operation and maintenance so as to ensure optimum performance and long life span of these systems. Therefore this study reports on needs assessment for operation and maintenance of CW systems in Tanzania. Together with the performance data, this could pave way to developing operation and maintenance guidelines for maintaining consistently good performance and longer life span of this technology. Abstract INTRODUCTION