Spatiotemporal trends of eight sewage contaminants in Brisbane, Australia, from 2012 – 2020

This study aims to investigate the spatiotemporal trends to the profile of contaminants in the influent of wastewater treatment plants (WWTPs) around Brisbane, Australia. One 24-hr composite influent sample was collected from 10 WWTPs and analysed for a range of contaminants per week (i.e., chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), ammonia, volatile suspended solid (VSS)) and per month (i.e., Ni and Cr) from 2012 to 2020. The catchments studied were urban, with a mix of domestic and industrial activities contributing towards the contaminant profile. Statistical analysis identified that industrial and commercial land use, as well as population size had a large impact to the contaminant loads and profile. Per capita mass loads and concentration of Cr in one catchment were one hundred times higher than in others from one industrial point source. TP demonstrated a potential monotonic decrease over time due to practical reduction policies that have been implemented for phosphorous content in household detergents, except for one catchment where trade waste from food manufacturing industries contributed to an overall increase of 6.9%/year TP. Through this process, this study enhances the interpretations of spatiotemporal trend of contaminants in the catchments for further effective source control.