Abstract:Wastewater produced from the oil refinery of the Maoming Petro-Chemical Company, China Petro-Chemical Corporation contains high concentrations of organic and inorganic pollutants, therefore it cannot be discharged directly into river or sea unless being treated first. Four plant species, Vetiveria zizanioides, Phragmites australis, Typha latifolia, and Lepironia articutala were planted in large containers as constructed vertical flow wetland to test their efficiencies in the purification of oil refined wast...