Effects of Detention Period and Sand-Based Surface Flow Constructed Wetland in Kitchen Wastewater Treatment using Phragmites Australis (Common Reed) as Macrophyte

Abstract

A greenhouse laboratory-scale experiment was conducted at the Department of Civil Engineering, Ladoke Akintola University of Technology (LAUTECH) Ogbomoso, Nigeria in May 2013 to demonstrate the performance of free water surface-flow sand- based constructed wetland, prepared with locally available plants, specifically common reed (Phragmites australis), as a viable low-cost efficient treatment option for domestic wastewater from kitchen. The nutrient removal and performance evaluation of the constructed wetland in treatment of kitchen wastewater was investigated. Treatment efficiency was evaluated during the 10-day retention period, and results indicated that the nutrients reduction corresponds to a longer retention time in wetland beds. There is a remarkable reduction in B.O.D (38.2-100%), hardness (100%), turbidity (55.2-77.2%), Nitrate (66.7-100%), zinc, ORP (45.0-79.1%), Sulphite (24-100%) sulphate (100%), TSS (55.2-82.3%) and little reduction in TDS (6.93-40%) and also there was increase in pH (31.7-45.6%), Magnessium (16.7-50%), Iron (50-75%), calcium ( 16.7-50%) The final effluent was found to be suitable for non-drinking purposes like crop irrigation, keeping aquatic animals and direct discharge into a receiving water body as the concentrations were well below allowable limits.The treatment system was found to be economical, as the cost of construction only was involved and maintenance cost very minimal. It was environmentally friendly as it was free from offensive odour and insect invasion. A pilot scale constructed wetland is recommended for further research works.

Keywords: Constructed wetland, Kitchen wastewater, Nutrient removal, Retention period, Phragmites australis