New developments in stormwater characterization and remediation for water reuse

University of Technology Sydney. Faculty of Engineering and Information Technology.Water scarcity due to persistent drought is forcing many countries around the world to explore alternative freshwater resources. Australia is the world’s driest inhabited continent, and has one of the most variable rainfall intensities. This has encouraged the harvesting of stormwater and reuse of water in order to reduce the demand placed on municipal water supplies. Urban and industrial stormwater runoff has high potential as a reusable water resource for agricultural irrigation, irrigation of parks and sportsgrounds, and toilet flushing. However, stormwater contains many pollutants which can have dire effect on plants, animals, aquatic organisms and humans and for this reason they should be removed before the water is used for these beneficial purposes. Assessing urban stormwater quality by investigation and characterisation of pollutants is a prerequisite for its effective management, for reuse and safe discharge. The stochastic nature of rainfall, dry weather periods, topology, human activities and climatic conditions generate and wash-off pollutants differently from event to event. Therefore, a study was commenced to investigate the major physico-chemical pollutants in stormwater runoff collected from an urban catchment system after several rainfall events over a period of three years. Correlation analysis and principal component analysis (PCA) were done to identify the possible relationships among measured pollutants. Although correlation analysis revealed some relationships between pollutants, PCA biplots suggested a few group-related pollutants and revealed that a two-component model could explain nearly 72% of the variability between pollutants. Pollutants in the group that included dissolved organic carbon (DOC) behaved in a similar manner. Most of the pollutants were washed off during an early stage of an event giving rise to the first flush phenomenon. UV spectroscopy was applied to identify the first flush by comparing the recorded spectrum of consecutive samples that were collected in an event. Analysis of the spectra was able to isolate the point when first flush ends for DOC and pollutants that behaved similar to it. The second part of the thesis dealt with remediation of stormwater by removing important organic and inorganic pollutants. Organic pollutants and heavy metal concentrations in stormwater are expected to increase and reach toxic levels in the near future because of rapid urbanisation leading to increasing density of motor vehicles. Polycyclic aromatic hydrocarbons are a group of highly persistent, toxic and widespread environmental micropollutants that are increasingly found in water […