K, Purushotorman K3, M. Christie1,3, M. Sheludchenko1,5, C. J. Lemckert1,2, A. Roiko1,4, H. M. Stratton1,3*
1Smart Water Research Centre, Griffith University, Gold Coast, Queensland, Australia 2School of Engineering, Griffith University, Gold Coast, Queensland, Australia 3School of Natural Sciences, Griffith University, Gold Coast, Queensland, Australia 4School of Medicine, Griffith University, Gold Coast, Queensland, Australia 5University of the Sunshine Coast, Queensland, Australia(free)
Maturation ponds/lagoons are used worldwide as secondary or tertiary steps for wastewater treatment, and in some cases, as the only treatment. In Australia, hundreds of municipal treatment systems rely on pond technology (facultative and maturation ponds) as a disinfection process, particularly in smaller towns and rural areas. Larger treatment plants also sometimes rely on maturation ponds for additional disinfection (polishing) purposes. The treated water is either returned to the environment or reused for non-potable purposes such as irrigation. One such system under investigation included a constructed wetland and reed bed system before the water was chlorinated released to a neighboring property for irrigation. The work presented here set out to identify the source of the fluctuations in E. coli, with increasing numbers after the water left the maturation pond. This was achieved using several Microbial Source Tracking (MST) techniques, including detection of Bacteroides genetic markers, E. coli typing using phylogenetic grouping and analyses of the β-glucuronidase. The results from the phylogenetic grouping suggested that the population of E. coli found in the maturation pond was not the same as the populations found in the constructed wetlands and reed beds. The analyses of the β-glucuronidase gene also implicated the isolates from each site to be from different sources. Analyses of both the phylogenetic grouping and β-glucuronidase gene showed that the E. coli isolates from all sites came from both human and animal sources. Bacteroides markers specific to human hosts identified that there was a new source of Bacteroides in the constructed wetlands and reed beds. The results demonstrate that the constructed wetlands and reed beds do not reduce pathogens from the water and thus may not be the best choice of alternative treatments of effluents from maturation ponds.