Assessment of pathogen removal efficiency of vertical flow constructed wetland treating Septage

Abstract

Abstract A laboratory-scale Constructed Wetland (CW) system consisting of a sludge drying bed and a vertical flow wetland bed was utilized for the treatment of septage, focusing on the reduction of microbial contamination (specifically total coliforms) and helminth eggs. The system had a total area of 0.99 m2. The sludge drying bed and vertical flow bed were filled with a combination of gravel with varying sizes (ranging from 5 to 40 mm) and washed sand. Canna indica plants were cultivated on both beds to facilitate phytoremediation processes. The average inlet loads of Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS) were measured as 150 ± 65.7 g m-2 d-1, 713 ± 443.9 g m-2 d-1, and 309 ± 66.3 g m-2 d-1, respectively. After treatment, the final effluent had an average load of 6 g m-2 d-1 for BOD, 15 g m-2 d-1 for COD, and 51 g m-2 d-1 for TSS, indicating that the CW system achieved an average removal efficiency of 88% for BOD, 87% for COD, and 65% for TSS in the septage wastewater. The average influent load of total coliforms and helminth eggs was observed to be 4 x 108 Colony-Forming Units (CFU) m-2 d-1 and 3 x 107 eggs m-2 d-1, respectively. However, the CW system demonstrated significant effectiveness in reducing microbial contamination, with an average removal efficiency of 99% for both total coliforms and helminth eggs. As a result, the total coliform and helminth egg loads in the effluent were reduced to 9 x 105 CFU m-2 d-1 and 1.6 x 104 eggs m-2 d-1, respectively.