This project provided an on-line monitoring protocol utilizing fluorescence to aid utilities in their provision of safe drinking water thus addressing the National Research Priority Goal “Water – A critical resource”

PhD Thesis completed by Yulia Shutova in October 2014.

Raw source water contains parts of plants, blue-green algae and their toxins, and many other types of organic matter. Identifying the types and amounts of organic matter helps treatment plant operators make informed decisions about the most efficient and cost-effective methods for treating and removing unwanted substances from source waters. The problem is that many of the tests for identifying organic compounds can take hours to days to deliver results. This research developed a test that gives information immediately. It uses three commercially available fluorescent probes that each emit fluorescent light at a specific wavelength. Certain compounds within organic matter, such as proteins, “reflect” the fluorescent light, but at different wavelengths which can be detected by the probes. These patterns of “reflected” fluorescence were related to traditional tests for organic compounds. This on-line fluorescence monitoring was then trialled at real-world treatment plants. The patterns gave reliable information about broad categories of organic compounds and there was a linear correlation between dissolved organic carbon and fluorescent intensity in both raw and treated waters. This research has provided a valuable addition to the suite of tools available for producing safe, high quality drinking water.

One wastewater treatment (WWT) option is disinfection with ultra violet (UV) light to remove pathogens and some contaminants, but substances in treated wastewater, such as particles of solid matter, can absorb the UV radiation and reduce its disinfecting activity. This research identified the sources of substances which are not removed by standard WWT plant processes, and which impair UV disinfection. It was concluded that trade wastes are a major source of organic, non-biodegradable humic-like substances which pose more of a problem to UV disinfection than total suspended solids. A sensor-probe based method for analysing fluorescence (‘EEM-PARAFAC’) was found to be an effective way to evaluate amounts of humic-like substances in effluents, and this information will improve management of UV WWT.

Water treatment plant operators remove cyanobacteria and the toxins they produce from source waters but calculating the amount of treatment needed for effective removal is difficult, particularly in bloom conditions when cyanobacterial cell numbers and toxins change quickly. Current cell counting and toxin measurement can take hours or days to complete, and the results are not available quickly enough to help treatment plant operators respond to changing conditions. There is a need for a real-time method that gives instant results. This research examined the utility of fluorometers; probes that emit light that is ‘reflected’ back at different wavelengths by living cells and other matter in the water and is detected by the fluorometer. It was found that when only one species of cyanobacteria was present, there was a good correlation between the fluorescent signal and cell number, particularly when source waters were clear and not cloudy. Cell numbers did not relate well to levels of toxins or taste and odour compounds. When fluorometers were installed in 13 water treatment plants the correlation between cyanobacteria cell numbers and fluorometer signals was validated, and this led to the conclusion that fluorometers can give early warning of blue-green algae blooms.

The aim of this project was to examine the utility of ultra-violet (UV) spectroscopy as a real-time water quality monitoring system. Two case studies were conducted. One assessed stormwater and showed that the UV system could detect that the first flush contained chemicals used as surrogates for water quality whereas later flows contained bacterial and biological markers. From this it was concluded that the sources of bacteria and chemicals were probably physically separated until they were mixed during surface runoff. In the second case study, the UV measurement equipment was set up in a groundwater filtration plant. It proved possible to accurately characterise water quality changes and assist operational decision-making.