Application of Pilot-Scale-Constructed Wetland as Tertiary Treatment System of Wastewater for Phosphorus and Nitrogen Removal

This paper presents the results of using a pilot-scale-constructed wetland as a tertiary system to simulate the treatment conditions of wastewater effluents from the metal-mechanical industry, aiming to achieve the Brazilian legal standards of phosphorus and nitrogen emission. The macrophytes were placed in 1 m 3 polyethylene tanks, daily estimating the treatment of 2 m 3 of effluents. The effluents were circulated in a horizontal subsurface flow through a porous matrix of thick sand and gravel, in which the roots of the macrophytes of the species Reed ( Scirpus sp.) and Cattail ( Typha sp.) were fixed. Monitoring of the pilot plant was performed through a battery of physical–chemical and biological analyses. Despite the load variations and operational problems, the system presented a positive degree of pollutant efficiency removal, especially for phosphorus (73% medium), TKN (61% medium), and NH 4 –N (56% medium). Peak results were achieved during the last 3 months of monitoring. The chemical analysis of the support layer, plus the root system and aerial portion of the plants, revealed that these wastes could be used as fertilizer.