Faecal Source Tracking Along the Urban Waste Water Path

Since Robert Kochs fundamental work more than 100 years ago, microbial water quality testing has been relying on the cultivation of indicator bacteria. However, increasing demand for the ability to precisely describe the nature and extent of faecal contamination of water resources led to recent developments in the field of quantitative microbial faecal source tracking (QMST), as standard faecal indicators do not support faecal sources discrimination. In this respect, host-specific genetic Bacteroidetes 16S rRNA marker (GeBaM) detection, based on quantitative PCR (qPCR), promises unique possibilities for future applications. So far, research has focused on the selection of host-specific GeBaM and the establishment of their respective qPCR detection method. Almost no information is available on the fate of GeBaM once released from the intestinal tract and introduced into aquatic habitats. This lack of information strongly limits the environmental applicability since knowledge on the persistence and resistance of GeBaM in the respective water resource is a crucial requirement for sound QMST. The proposed research project will focus on the fundamental issue of human-specific faecal pollution of water resources in the temperate climatic zone by communal waste water disposal as prevalent in the Austrian and Bavarian region. The outcome of the investigation is going to establish the general knowledge on the quantitative occurrence, persistence, resistance and predictability of GeBaM cells from human sources in aquatic habitats. The following key issues will be addressed in detail: i) quantitative occurrence of general- and human-specific GeBaM (g/h-GeBaM) in raw waste water in respect to population size, type of sewer system, and season, ii) quantitative fate of g/h-GeBaM in comparison to standard and alternative indicators/pathogens during primary and biological waste water treatment with respect to treatment type, treatment conditions and season, iii) fate of g/h-GeBaM in primary and secondary sludge and sludge stabilisation procedures, iv) effect of advanced treatment on g/h-GeBaM abundance (UV, ozone, membrane filtration), v) elucidating the ecological factors which determine the fate of g/h- GeBaM in receiving waters, and finally, vi) establishing a simple model to predict g/h-GeBaM persistence in the water column as a function of season and trophic status of the water body within the temperate climatic zone. The research project is going to investigate a selection of representative waste water treatment plants differing in size and design (e.g. served population from 50 to 4.000.000 population equivalents) and on a number of various receiving water bodies ranging from oligotrophic to eutrophic conditions (including running and stagnant waters). Research collaboration partners were carefully chosen in order to provide highest expertise in the interdisciplinary fields of QMST, health-related water microbiology, conventional and advanced waste water treatment technology. The research outcome is going to provide the scientific basis needed for QMST along the urban water cycle in temperate regions. This foundation will support the integration of source tracking approaches in water resource management and risk assessment, eventually leading to economical as well as public health benefits.

Water of appropriate microbiological quality is of outstanding importance for public health. Increasing demand to precisely describe the nature, source and extent of microbial faecal pollution led to recent developments for genetic faecal marker detection from abundant host-associated gut bacteria. Detection of host-associated genetic faecal markers holds great promise to revolutionize water quality testing, as information about the source of faecal pollution can be gained for problem-oriented water quality management. The aim of this research effort was to establish lacking scientific knowledge on the occurrence, fate and removal of genetic human-associated Bacteroidetes faecal markers (GeBaM) in raw and treated waste water of municipal and domestic origin. Sound information on the environmental characteristics of human-associated GeBaM is of fundamental importance in order to support the application of intelligent water quality monitoring in the future. A strong scientific basis on the ubiquitous and abundant occurrence of human-associated GeBaM in raw and treated waste water, regardless whether the waste water was derived from disposal systems of single households, larger settlements, or towns, could successfully be established (more than one to 100 million marker occur in 100ml of raw and biologically treated waste water, respectively). Results cover a seasonal investigation of waste water from twelve accurately characterized and carefully chosen waste water treatment plants (WWTPs) in Austria and Germany. Results were also supported by investigations of waste water from 25 WWTPs from 15 countries on five continents. Methodical comparisons also indicated that GeBaM diagnostics can be performed with at least equal precision as compared to standard cultivation techniques or alternative viral indicators of faecal pollution. Finally, the established knowledge could successfully be incorporated into a newly developed water quality modeling program (QMRAcatch) for catchments. The application of human-associated GeBaM data supported model calibration to waste water-specific emission patterns within the test-catchments. Sustainable management scenarios to produce safe drinking water according to health-based-targets (as suggested by the World Health Organization) could then be derived by the calibrated QMRAcatch model. In conclusion, the performed research successfully generated the fundamental understanding to further promote the rapid development of this technology for molecular source tracking and water quality monitoring. Incorporation of the established methodology into a new water quality model also demonstrated the great potential of genetic markers for future drinking water safety scenario planning.