PERFORMANCE OF A SURFACE FLOW CONSTRUCTED WETLAND SYSTEM USED TO TREAT SECONDARY EFFLUENT AND FILTER BACKWASH WATER

• Main Authors: Juan Antonio Vidales-Contreras, Charles Peter Gerba, Martin M Karpiscak, Humberto Rodriguez-Fuentes, Cristobal Chaidez-Quiroz, Emilio Olivares-Saenz
• Format: Article
• Language: English
• Published: Universidad Autónoma de Yucatán 2011-05-01
• Series: Tropical and Subtropical Agroecosystems
• Subjects: TSS (SST), BOD5 (DBO5), constructed wetlands (pantanos construidos), wastewater (agua residual), backwash water (agua de retrolavado), microbial indicators
• Online Access: http://www.revista.ccba.uady.mx/ojs/index.php/TSA/article/view/486

  The performance of a surface flow wetland system used to treat activated sludge effluent and filter backwash water from a tertiary treatment facility was evaluated. Samples were collected before and after vegetation removal from the system which consists of two densely vegetated settling basins (0.35 ha), an artificial stream, and a 3-ha surface flow wetland. Bulrush (Scripus spp.) and cattail (Typha domingensis) were the dominant plant species. The average inflow of chlorinated secondary effluent during the first two months of the actual study was 1.9  m3 min-1 while the inflow for backwash water treatment ranged from 0.21 to 0.42 m3 min-1. The system was able to reduce TSS and BOD5 to tertiary effluent standards; however, monitoring of chloride concentrations revealed that wetland evapotranspiration is probably enriching pollutant concentrations in the wetland outflow. Coliphage removal from the filter backwash was 97 and 35% during 1999 and 2000, respectively. However, when secondary effluent entered the system, coliphage removal averaged 65%. After vegetation removal, pH and coliphage density increased significantly (p