Potential of constructed wetlands as an alternative for wastewater treatment to meet standards for reclamation and re-use in agriculture

Abstract

This research was  carried out to assess the performance of the Horizontal sub-surface flow Constructed Wetland (HSSFCW) system in polishing pre-treated wastewater in the UPward Flow Anaerobic sludge Blanket (UASB) reactor plant as a potential wastewater treatment system that can meet the requirement for wastewater recycling and re-use for agricultural purposes, The HSSFCW unit was designed and operated with a hydraulic loading of approximately  0.1m³ m²/ day and a hydraulic retention time of approximately four days and it was packed with fine gravel and sand with an average porosity of 48%. Faecal Coliforms in the effluent  which was in the magnitude of 7 log units was reduced to 3 log units while the mean Biological Oxygen demad (BOD5) in the final effluent was observed to be 5.6 mg/l.  These values meets the required removal efficiency recommended by World Health Organisation (WHO). Food and Agricultural organisation (FAD) and Tanzanian standards for wastewater re-use in irrigation suggesting therefore that the HSSFCW has potential and can be applied in the reclamation of wastewater for irrigation to benefit the society in terns of crop yields.

Keywords: Wastewater treatment, agricultural use, constructed wetland, re-use

Tanzania J.Agric. Sc.(2003)Vol. 6 No.1, 29-38