Pathogens and Trace Contaminants in Dams
Raw drinking water storages in South East Queensland (SEQ) are exposed to multiple sources of biological and chemical contaminants. To date, the engineered treatment plants have been highly effective, but also the sole treatment barrier. Natural systems such as reservoirs and streams have been used only as passive control mechanisms, but they can also be highly effective in reducing pathogens and chemical contaminants.
In order to more actively manage and use these "natural system" barriers – and thereby improve the overall effectiveness of the full process chain leading to drinking water production - it is important to understand the influence these systems have under a range of conditions. Because pathogen contamination of drinking water can constitute a significant health risk to communities, understanding the sources of these organisms and the risks they present is paramount to effectively managing the water supply.
This project focussed on investigating the mechanisms of decay of selected enteric pathogens and trace organic compounds in SEQ reservoirs and associated waterways under a range of physio-chemical, climatic and seasonal conditions. A key aspect was assessing the attenuation of contaminants at different depths of reservoir, different light inputs, a range of water temperature, chemistry and varying biological parameters. Additional research was undertaken to develop microbial source tracking techniques to determine whether the source of the pathogens was animal or human related. Research questions this project focused on were:
- What is the capacity of reservoirs to remove target pathogens under different conditions?
- What are the major influences affecting the removal rates in reservoirs?
- How effective is the mid-Brisbane river in removing pathogens and trace contaminants?
- Which contaminants and pathogens are likely to persist in the water column and what impact could this have?
- What are the major health risk exposure pathways for microbial pathogens in reservoirs, and what are the best control mechanisms?
Key Publications and Outputs
- Technical Report32 and 87 (as well as reports 20, 54, 55 and 56 dealing with pathogen attenuation in wastewater treatment)
- Conference papers listed on the Alliance website
- Proceedings of the Alliance Science Forums
A number of interrelated experiments, including evaluation of the impact of sunlight, were completed. This demonstrated that sunlight has an impact on pathogens at the reservoir surface but not at a 5m depth.
Information generated in this study will inform the development of contaminant fate models and health risk exposure assessments. Information developed through this project will be of high relevance to drinking water quality management plans and water grid quality management plan prepared in SEQ and further afield.
Dr Simon Toze, CSIRO
Ph: +61-7-3833 5572